Slide 1

What is the most likely mechanism of failure for the patellar component shown:

 

1) Fatigue

3) Tension

2) Shear

5) Delamination

4) Compression

 

Component fracture in a completely polyethylene patellar component is rare. Most patellar component failures involve metal-backed patellar components. Shearing of the fixation pegs from the remainder of the patellar component is a recognized complication of metal-backed patellar components. The same mechanism is responsible for the failure seen.Correct Answer: Shear

 

 

 

2. (209) Q1-317:

The minimum thickness of polyethylene required for the tibial component of a total knee prosthesis is:

 

1) 4 mm

3) 8 mm

2) 6 mm

5) 12 mm

4) 10 mm

 

Laboratory studies have demonstrated that a minimum of 12 mm polyethylene thickness is required to minimize cold extrusion. However, placement of a 12-mm polyethylene component would necessitate removal of an excessive amount of host bone.

Currently, the U.S. Food and Drug Administration requires use of at least 8 mm polyethylene thickness in total knee arthroplasty.Correct Answer: 8 mm

 

 

A 65-year-old man undergoes total knee revision without complication. Routine intraoperative cultures are submitted that are positive for growth of coagulase negative staphylococcus at 48 hours postoperative in 3 of 5 specimens. The patient is afebrile and his wound is dry. Appropriate treatment should include:

 

1) No further antibiotic therapy

3) Irrigation and debridement with retention of the components

2) Six weeks of parenteral antibiotics

5) Irrigation and debridement with removal of components and delayed exchange arthroplasty

4) Irrigation and debridement with one stage component exchange

 

 

Infected total knee arthroplasties can be placed into one of the following categories: Positive intraoperative cultures without gross evidence of infection

 

 

Early postoperative infection Late chronic infection

 

Acute hematogenous infection

Patients with positive intraoperative cultures can only be treated with 6 weeks of antibiotics. Early postoperative infections are treated with multiple debridements as indicated with retention of the prosthesis and antibiotic therapy. Late chronic infections are treated with component removal and delayed exchange arthroplasty. If treated early enough, acute hematogenous infections can be treated with irrigation and debridement with prosthetic retention.

 

Correct Answer: Six weeks of parenteral antibiotics

 

 

1. (211) Q1-319:

   When preoperatively templating a radiograph in preparation for the femoral component in total hip arthroplasty, the leg should be positioned in:

    

   1) Neutral rotation

   3) 30° internal rotation

   2) 15° internal rotation

   5) 30° external rotation

   4) 15° external rotation

    

   When templating the femoral component in total hip arthroplasty, positioning the leg in 15° internal rotation neutralizes the femoral anteversion. This gives a true anterior/posterior view of the proximal femur and allows for a more accurate templating of the femoral component.Correct Answer: 15° internal rotation

    

    

    

2. (212) Q1-320:

The most common complication following high tibial osteotomy for treatment of medial compartment knee arthrosis is:

 

1) Neurovascular injury

3) Undercorrection

2) Overcorrection

5) Patella baja

4) Compartment syndrome

 

Complications in high tibial osteotomy include undercorrection, overcorrection, osteonecrosis of the tibial plateau, patella baja, neurovascular injury, anterior compartment syndrome, and other complications common to all procedures. The most common of these is undercorrection.Correct Answer: Undercorrection

 

 

Which of the following is considered a contraindication to high tibial osteotomy for the treatment of medial compartment knee arthrosis:

 

1) 10° fixed varus deformity

3) Prior knee infection

2) Normal lateral compartment

5) 5° flexion contracture

4) Lateral tibial subluxation of 2 cm

 

High tibial valgus producing osteotomy attempts to redirect the forces crossing the knee joint from the medial compartment to slightly lateral to the center of the knee. Indications include isolated medial knee pain, less than 15° fixed varus deformity, a normal lateral compartment, and a normal patellofemoral compartment. Contraindications include:

 

 

 

Restricted knee motion (flexion contracture greater than 15° or flexion limited to less than 90°) Lateral tibial subluxation greater than 1 cm

 

 

Peripheral vascular disease Tibial bone loss

 

Lateral thrust gait pattern

Correct Answer: Lateral tibial subluxation of 2 cm

 

 

1. (231) Q1-341:

   Following acute traumatic patellar dislocation, the most important injured structure in regard to future instability of the patellofemoral joint is the:

    

   1) Medial parapateller retinaculum

   3) Medial patellofemoral ligament

   2) Vastus medialis obliquis

   5) Medial patellomeniscal ligament

   4) Medial patellotibial ligament

    

   The medial patellofemoral ligament is the primary restraint to lateral subluxation of the patella. The other structures above contribute less substantially to patellofemoral stability. In the majority of cases of acute traumatic patellar dislocation, the medial patellofemoral ligament is disrupted.Correct Answer: Medial patellofemoral ligament

    

    

    

2. (233) Q1-344:

The most common sequelae following traumatic shoulder dislocation in an 18-year-old man is:

 

1) Normal shoulder without further problems

3) Axillary nerve injury

2) Recurrent shoulder dislocation

5) Adhesive capsulitis

4) Rotator cuff tear

 

Up to 90% of young patients with a traumatic shoulder dislocation will have a recurrent dislocation. Rotator cuff tears occur commonly with shoulder dislocation in the older population, but are relatively uncommon in younger patients.Correct Answer: Recurrent shoulder dislocation

 

 

A 55-year-old woman has rheumatoid arthritis with shoulder, elbow, and hand/wrist symptoms. No single site of involvement is more symptomatic than the others. After failure of nonoperative treatment, the appropriate order of surgical intervention is:

 

1) Hand/wrist, elbow, shoulder

3) Elbow, shoulder, hand/wrist

2) Shoulder, elbow, hand/wrist

5) Shoulder, hand/wrist, elbow

4) Hand/wrist, shoulder, elbow

 

Generally speaking, the more symptomatic joints are addressed first in rheumatoid arthritis. However, when upper extremity joints are equally disabling, the hand and wrist disability is addressed first. Although it is somewhat controversial, it is generally agreed that the shoulder should be addressed before the elbow. This eliminates referred pain from the shoulder to the elbow, allowing for better evaluation of elbow symptoms. Addressing the shoulder pathology earlier may prevent ensuing rotator cuff tears that can compromise results of arthroplasty. Lastly, increasing shoulder mobility may decrease the stresses on an arthritic elbow.Correct Answer: Hand/wrist, shoulder, elbow

 

 

1. (533) Q1-735:

   The normal version of the glenoid is:

    

   1) 20º to 30° retroversion

   3) Neutral to 10° retroversion

   2) 10° to 20° retroversion

   5) 10° to 20° anteversion

   4) Neutral to 10° anteversion

    

   The normal version of the glenoid has been established to be between neutral and 10° of retroversion. Excessive glenoid retroversion can indicate excessive posterior wear caused by primary osteoarthritis. Retroversion in excess of 25° can indicate glenoid dysplasia.Correct Answer: Neutral to 10° retroversion

    

    

2. (534) Q1-736:

   Posterior translation of the humeral head is associated with which of the following arthritic etiologies:

    

   1) Primary osteoarthritis

   3) Post-infectious arthritis

   2) Rheumatoid arthritis

   5) Post-traumatic arthritis

   4) Arthritis secondary to osteonecrosis

    

   Primary osteoarthritis of the shoulder is a well-described entity. Neer described posterior subluxation of the humeral head following posterior glenoid erosion. Although the exact sequence of events has recently come into question, the end result is a static posterior subluxation of the humeral head with arthritis.Correct Answer: Primary osteoarthritis

    

    

3. (535) Q1-737:

Which of the following statements best describes the most common scenario in regard to the rotator cuff in patients with primary osteoarthritis of the shoulder:

 

1) Intact rotator cuff

3) Rupture of the supraspinatus tendon only

2) Thin, attenuated rotator cuff

5) Massive rupture of the rotator cuff

4) Rupture of the subscapularis tendon only

 

In most situations of primary osteoarthritis, the rotator cuff is intact or has minimal tearing.Correct Answer: Intact rotator cuff

 

When performing total shoulder arthroplasty, a subscapularis tenotomy is performed as part of the surgical exposure. The following anatomic landmark provides the greatest information regarding the point of initiation of the subscapularis tenotomy:

 

1) Pectoralis major tendon

3) Deltoid insertion on the humerus

2) Pectoralis minor tendon

5) Anterolateral aspect of the acromion

4) Biceps tendon

 

It is important to identify the superior aspect of the subscapularis tendon prior to performing subscapularis tenotomy in the surgical exposure for shoulder arthroplasty. With an intact rotator cuff, identification of the superior aspect of the subscapularis tendon at the rotator interval can be difficult. If the biceps tendon is located just medial to the humeral insertion of the pectoralis major and followed superior, the rotator interval can be located and opened, allowing visualization of the superior aspect of the subscapularis tendon. In the event that the biceps tendon is ruptured or dislocated, the base of the coracoid process can be used to identify the medial aspect of the rotator interval.Correct Answer: Biceps tendon

 

 

1. (537) Q1-739:

   All of the following are involved in rotator cuff tear arthropathy except:

    

   1) Osteonecrosis

   3) Rupture of the rotator cuff

   2) Chondrolysis

   5) Acromiohumeral arthritis

   4) Hydroxyapatite crystal deposition

    

   Cuff tear arthropathy includes osteonecrosis and acromiohumeral arthritis with a rotator cuff tear. Other investigators discovered hydroxyapatite crystal deposition as well. Chondrolysis is not a part of rotator cuff tear arthropathy, but can occur if the individual develops secondary osteoarthritis.Correct Answer: Chondrolysis

    

    

2. (538) Q1-740:

   The outcome of patients with osteoarthritis of the shoulder is better after total shoulder arthroplasty compared to humeral arthroplasty with regard to:

    

   1) Strength

   3) Active forward elevation

   2) Pain relief

   5) Ability to sleep

   4) Active external rotation

    

   In his prospective study of 51 shoulder arthroplasties, Gartsman found that pain relief and internal rotation were significantly better in patients that had undergone glenoid resurfacing compared to hemiarthroplasty. Patient satisfaction, function, and strength were also higher, but these differences were not statistically different.Correct Answer: Pain relief

    

    

3. (539) Q1-741:

The outcome of patients with rheumatoid arthritis of the shoulder and an intact rotator cuff is better after total shoulder arthroplasty compared to humeral arthroplasty with regard to:

 

1) Strength

3) Active forward elevation

2) Pain relief

5) Ability to sleep

4) Active external rotation

 

Provided the rotator cuff is intact, glenoid resurfacing is preferred in patients with rheumatoid arthritis of the shoulder because of better pain relief than isolated humeral arthroplasty.Correct Answer: Pain relief

 

Which of the following is most closely associated with glenoid loosening following total shoulder arthroplasty?

 

1) Dysfunction of the rotator cuff

3) Osteoarthritis

2) Rheumatoid arthritis

5) Osteonecrosis

4) Chondrocalcinosis

 

Although glenoid loosening occurs more frequently in patients with rheumatoid arthritis than osteoarthritis, this loosening occurs secondary to the dysfunction of the rotator cuff. Similarly, osteoarthritic patients may suffer from the same type of glenoid loosening in the absence of a functioning rotator cuff. Eccentric loading caused by the cuff deficiency can lead to progressive loosening and a "rocking horse glenoid."Correct Answer: Dysfunction of the rotator cuff

 

 

1. (541) Q1-743:

   All of the following are considered contraindications to glenoid resurfacing during shoulder arthroplasty except:

    

   1) Dysfunctional deltoid

   3) Prior infection

   2) Dysfunctional rotator cuff

   5) Patient age < 50 years

   4) Inadequate glenoid bone stock

    

   While glenoid loosening rates are higher in younger patients, this does not preclude glenoid resurfacing in all cases. The remaining choices are all contraindications to glenoid resurfacing.Correct Answer: Patient age < 50 years

    

    

2. (542) Q1-744:

   The anatomical neck to humeral shaft angle averages:

    

   1) 30° to 35°

   3) 40° to 45°

   2) 35° to 40°

   5) 50° to 55°

   4) 45° to 50°

    

   The average neck-shaft angle in the humerus is 40° to 45°; however, a large range has been reported (30° to 55°). This variability has led to the anatomical concept of prosthetic adaptability pioneered by Walch.1 Correct Answer: 40° to 45°

    

    

3. (570) Q1-792:

An absolute contraindication to glenoid resurfacing when performing shoulder arthroplasty is:

 

1) Patient <50 years of age

3) Insufficient bone stock

2) Presence of a small supraspinatus tear

5) Presence of an inflammatory arthropathy

4) Presence of osteonecrosis of the humeral head

 

Sufficient bone stock must be present to implant a glenoid component when performing shoulder arthroplasty. While hemiarthroplasty in a young patient without arthritic changes of the glenoid can be considered, age is not considered an absolute contraindication to glenoid resurfacing. While the presence of a large rotator cuff tear represents a contraindication to glenoid resurfacing because of the "rocking horse" effect, which results in glenoid loosening, a small reparable rotator cuff tear does not prohibit resurfacing. Glenoid resurfacing is not contraindicated in osteonecrosis or rheumatoid arthritis provided there is a competent rotator cuff.Correct Answer: Insufficient bone stock

 

 

 

 

 

Figure 1

The glenoid morphology depicted in the slide is most often associated with the following etiology:

 

1) Primary osteoarthritis

3) Osteonecrosis

2) Rheumatoid arthritis

5) Post-infectious arthritis

4) Post-traumatic arthritis

 

 

The slide depicts a type B2 biconcave glenoid as classified by Walch secondary to primary OA. Correct Answer: Primary osteoarthritis

 

1. (572) Q1-799:

   Positioning of the humeral stem at the time of total shoulder arthroplasty should allow congruent articulation with the glenoid component. Congruent articulation occurs in most shoulders with a humeral stem positionedin:

    

   1) Neutral version

   3) 20° to 30° of retroversion

   2) 10° to 20° of retroversion

   5) 20° to 30° of anteversion

   4) 10° to 20° of anteversion

    

   It is important to place the humeral stem in appropriate version to "mate" with the glenoid component. This is most often represented by 20° to 30° of humeral retroversion.Correct Answer: 20° to 30° of retroversion

    

    

2. (573) Q1-801:

Posterior translation of the humeral head is associated with which of the following arthritic etiologies:

 

1) Primary osteoarthritis

3) Post-infectious arthritis

2) Rheumatoid arthritis

5) Post-traumatic arthritis

4) Arthritis secondary to osteonecrosis

 

Primary osteoarthritis of the shoulder is a well-described entity. Neer described posterior subluxation of the humeral head following posterior glenoid erosion.1 Although the exact sequence of events has recently come into question, the end result is a static posterior subluxation of the humeral head with arthritis.Correct Answer: Primary osteoarthritis

 

All of the following are involved in rotator cuff tear arthropathy except:

 

1) Osteonecrosis

3) Rupture of the rotator cuff

2) Chondrolysis

5) Acromiohumeral arthritis

4) Hydroxyapatite crystal deposition

 

Cuff tear arthropathy includes osteonecrosis and acromiohumeral arthritis with a rotator cuff tear. Other investigators discovered hydroxyapatite crystal deposition as well. Chondrolysis is not a part of rotator cuff tear arthropathy, but can occur if the individual develops secondary osteoarthritis.Correct Answer: Chondrolysis

 

 

1. (575) Q1-806:

   The outcome of patients with rheumatoid arthritis of the shoulder and an intact rotator cuff is better after total shoulder arthroplasty compared to humeral arthroplasty with regard to:

    

   1) Strength

   3) Active forward elevation

   2) Pain relief

   5) Ability to sleep

   4) Active external rotation

    

   Provided the rotator cuff is intact, glenoid resurfacing is preferred in patients with rheumatoid arthritis of the shoulder because of better pain relief than isolated humeral arthroplasty.Correct Answer: Pain relief

    

    

2. (576) Q1-808:

All of the following are considered contraindications to glenoid resurfacing during shoulder arthroplasty except:

 

1) Dysfunctional deltoid

3) Prior infection

2) Dysfunctional rotator cuff

5) Patient age <50 years

4) Inadequate glenoid bone stock

 

While glenoid loosening rates are higher in younger patients, this does not preclude glenoid resurfacing in all cases. The remaining choices are all contraindications to glenoid resurfacing.Correct Answer: Patient age <50 years

 

 

Figure 1

This slide is the radiograph of a 70-year-old man with unremitting shoulder pain despite nonoperative interventions. Recommended treatment includes:

 

1) Administration of narcotic pain medications

3) Open rotator cuff repair

2) Arthroscopic rotator cuff repair

5) Total shoulder arthroplasty

4) Humeral head arthroplasty

 

The radiograph demonstrates arthropathy in the presence of rotator cuff deficiency (as indicated by upward migration of the humeral head). The patient has already failed reasonable medical treatment and surgical intervention is warranted. The presence of significant arthrosis with upward migration of the humeral head combined with the patientâs age precludes consideration of rotator cuff repair, although debridement could be considered. Total shoulder arthroplasty is contraindicated because the deficient cuff would almost certainly result in glenoid loosening from eccentric loading. Humeral head arthroplasty would provide some pain relief with limited return of function, and at this time, is the best surgical option for this patient.Correct Answer: Humeral head arthroplasty

 

 

 

28. (578) Q1-811:

 

 

 

Figure 1

The goal in performing glenoid resurfacing during total shoulder arthroplasty for the patient whose computed tomogram is shown in this slide should be:

 

1) Placement of the glenoid component in situ

3) Placement of the glenoid component in neutral to 10° of retroversion

2) Placement of the glenoid component in neutral to 10° of anteversion

5) Placement of the glenoid component in excess of 20° of retroversion

4) Placement of the glenoid component in 10° to 20° of retroversion

 

The computed tomogram depicts a type B2 glenoid with excessive posterior wear resulting in biconcavity and excessive glenoid retroversion. The goal of glenoid arthroplasty should be to reestablish normal glenoid retroversion between neutral and 10°. This may be done with reaming or, in severe cases, may necessitate the use of a posterior bone graft. Implanting the glenoid component in excessive retroversion may result in postoperative instability.Correct Answer: Placement of the glenoid component in neutral to 10° of retroversion

 

 

Figure 1

This slide is an intraoperative photograph during total shoulder arthroplasty. The findings in this slide most likely represent which of thefollowing diagnoses:

 

1) Primary osteoarthritis

3) Rheumatoid arthritis

2) Rotator cuff tear arthropathy

5) Postinfectious arthropathy

4) Osteonecrosis

 

The large amount of crown osteophytes present in this slide suggest a diagnosis of primary osteoarthritis. It is necessary to remove these osteophytes in order to identify the anatomical neck of the humerus and make the correct humeral head resection.Correct Answer: Primary osteoarthritis

 

 

30. (580) Q1-813:

 

 

 

Figure 1

This slide shows a magnetic resonance image from a patient with shoulder pain. Based on the findings of this image, the following procedure is contraindicated:

 

1) Subacromial corticosteroid injection

3) Shoulder arthrodesis

2) Arthroscopic debridement of the rotator cuff

5) Unconstrained total shoulder arthroplasty

4) Humeral head arthroplasty

 

The magnetic resonance image depicts near complete fatty infiltration of the supraspinatus muscle and, more importantly, the infraspinatus muscle. Initially, fatty degeneration of the cuff musculature was described as a poor prognostic indicator for rotator cuff function using computed tomography. These observations were also applied to magnetic resonance imaging. Walch advises against performing unconstrained total shoulder arthroplasty in patients with a dysfunctional cuff as indicated by fatty degeneration of the infraspinatus because of poorer results regarding pain relief and active mobility.1 Furthermore, this degeneration can lead to early glenoid loosening from eccentric loading.Correct Answer: Unconstrained total shoulder arthroplasty

 

 

 

 

 

Figure A Figure B

A 42-year-old male has a history of 6 months of pain in the lower thoracic region. Recently, the patient developed weakness in the right lower extremity, bladder and bowel movement. Plain x-rays were normal, but an magnetic resonance imaging (MRI) showed a posterolateral thoracic disk herniation at the level of T10-T11 (Slides 1 and 2). Which of the following is the best suggested treatment?

 

1) Bed rest

3) Laminectomy and decompression

2) Thoraco-lumbar orthosis

5) Thoracotomy, vertebractomy, strut graft and internal fixation

4) Diskectomy through thoracotomy or costotransverectomy

 

Conservative treatment should be considered for patients without major neurologic deficits. Posterior laminectomy and decompression provides inadequate exposure of the herniated Disk. Vertebractomy, strut bone graft and instrumentation are not necessary. Thoracotomy and costotransversectomy are commonly used for disk herniations at the levels of T4-T12.Correct Answer: Diskectomy through thoracotomy or costotransverectomy

 

 

1. (663) Q1-915:

   The patient was diagnosed with spinal stenosis of the lumbosacral spine. In addition to educating the patient about his condition, the most appropriate initial treatment is:

    

   1) Walking program

   3) Lumbar traction

   2) Nonsteroidal anti-inflammatory drugs

   5) Cortisone administration

   4) Spinal decompression and fusion

    

   Initial treatment begins with patient education, a physical therapy regime (gentle conditioning exercises), judicious activity change, and sometimes spinal support with a corset or light-weight brace. Anti-inflammatory nonsteroidal drugs provide some relief of symptoms for many patients.Correct Answer: Nonsteroidal anti-inflammatory drugs

    

    

2. (664) Q1-916:

The patient's clinical diagnosis is degenerative spondylolithesis. In what patient population is this condition most commonly symptomatic?

 

1) Pre-teen males

3) Males over 70 years old

2) Females 40 to 70 years old

5) Males 20 to 30 years old

4) Females 20 to 30 years old

 

Degenerative spondylolithesis is most frequently symptomatic in the 40 to 70 year old range and is six times more common in females than in males. This population appears to have enough disk degeneration and motion to become symptomatic whereas the older population tend to have aquired enough ankylosis at the level to prevent instability symptoms.Correct Answer: Females 40 to 70 years old

 

The biceps electromyographic activity is greatest during which of the following elbow motions:

 

1) Elbow extension from 90° of flexion

3) Elbow supination at 45° of flexion

2) Elbow supination at 90° of flexion

5) Flexion from 90° in pronation

4) Flexion from 90° in supination

 

Electromyographic activity of the biceps is greatest from flexion at 90° in supination indicating that this arc of motion is where there is the most sustained contraction of the biceps muscle.Correct Answer: Flexion from 90° in supination

 

 

1. (666) Q1-919:

   Which of the following is not an appropriate method of treating an elbow joint contracture that has been present for less than 1 year:

    

   1) Closed manipulation

   3) Static adjustable splinting (turnbuckle splint)

   2) Local heat

   5) Active gentle-assisted stretch

   4) Dynamic hinged elbow splint

    

   The least appropriate treatment for elbow joint contracture is closed manipulation. The elbow is a sensitive joint, and strenous closed manipulation leads to more bone formation or even possible fracture. The other less drastic measures are more appropriate treatment methods.Correct Answer: Closed manipulation

    

    

2. (667) Q1-920:

   The principle complication of constrained and semiconstrained total elbow arthroplasty is:

    

   1) Heterotopic bone formation

   3) Loosening of the ulnar component

   2) Elbow subluxation and instability

   5) Loosening of the humeral component

   4) Stress shielding in the humerus

    

   Ulnar component loosening is the most common complication of total elbow arthroplasty. Although other complications also occur, they are less common.Correct Answer: Loosening of the ulnar component

    

    

3. (668) Q1-921:

The best method for testing the integrity of the anterior oblique band of the medial collateral ligament is:

 

1) Valgus stress in 30° of flexion and full supination

3) Varus stress in 30° of flexion and slight pronation

2) Valgus stress in 60° of flexion and neutral rotation

5) Varus stress in full extension and full pronation

4) Valgus stress in 30° of flexion and full pronation

 

The anterior oblique band of the medial collateral ligament is best tested by valgus stress when the elbow is at 30° of flexion and full pronation.Correct Answer: Valgus stress in 30° of flexion and full pronation

 

Which tendon transfer results in the greatest recovery of thumb-index finger pinch function?

 

1) Flexor digitorum superficials of ring finger

3) Extensor digitorum communis

2) Extensor indicis proprius

5) Flexor digitorum superficials of middle finger

4) Extensor carpi radialis brevus

 

The extensor carpi radialis brevus or extensor carpi radialis longus transfer gives the greatest return of power pinch due to the strength of the wrist motors. This should also be coupled with a thumb MP arthrodesis to provide best results.Correct Answer: Extensor carpi radialis brevus

 

 

1. (720) Q1-981:

   Which of the following terms is used to describe a localized conduction block in a peripheral nerve in which the axon is disrupted with the intact endoneurial tube:

    

   1) First-degree injury (neuropraxia)

   3) Third-degree

   2) Second-degree (axonotmesis)

   5) Fifth-degree

   4) Fourth-degree

    

    

   First-degree: Neuropraxia, the nerve structure is intact, full recovery is expected

    

   Second-degree: Axonotmesis, severance of the axon leading to Wallerian degeneration, continuity of endoneurial sheath is maintained, repair is orderly, complete motor and sensory loss with denervation and fibrillation potentials

    

   Third-degree: Injury to axons and the endoneurial tube, arrangement of individual fascicles is maintained (perineurium intact), recovery is variable

    

   Fourth-degree: Injury to axons, endoneurial tube, fascicles with the nerve trunk being intact, Wallerian degeneration and a higher incidence of proximal nerve cell body degeneration, repair is unlikely and surgical repair of the nerve is necessary (excision and grafting)

    

    

   Fifth-degree: Loss of nerve trunk continuity, neuroma formation in the proximal stump, wallerian degeneration distally Correct Answer: Second-degree (axonotmesis)

    

2. (967) Q1-1270:

   When a patient has his or her hip flexed, which nerve can be palpated at the midpoint between the ischial tuberosity and the greater trochanter:

    

   1) Obturator nerve

   3) Peroneal nerve

   2) Femoral nerve

   5) No nerve typically exists in that region

   4) Sciatic nerve

    

   The sciatic nerve is in the posterior compartment of the thigh and can be palpated at the midpoint between the ischial tuberosity and the greater trochanter when the hip is flexed.

    

    

   The obturator nerve is in the medial compartment of the thigh. The femoral nerve is in the anterior compartment of the thigh.

    

   The peroneal (common peroneal) nerve bifurcates into the deep peroneal and the superficial peroneal nerves which lie in the anterior and lateral compartments of the leg, respectively.

   Correct Answer: Sciatic nerve

    

3. (999) Q1-1306:

   The principal thrombogenic stimulus leading to the production of venous thromboembolic disease during total hip arthroplasty occurs at which time:

    

   1) During induction of anesthesia

   3) 12 hours postoperative

   2) During and after preparation of femoral canal

   5) 7 days postoperative

   4) 24 hours postoperative

    

   Evidence has shown that the process of thrombosis does not begin with the start of the procedure, rather, it is delayed until preparation of the femoral canal. Elevation in thrombogenic factors is most pronounced during preparation of the femoral canal and especially with insertion of a cemented femoral component. Mechanical manipulation of the limb (dislocation of the femoral head) may also cause intimal damage or occlusion of the femoral vein.Correct Answer: During and after preparation of femoral canal

    

    

    

4. (1000) Q1-1307:

   Place the following in the correct order of increasing modulus of elasticity (from least to greatest):

    

   1) Cobalt-chrome, titanium, compact bone, stainless steel

   3) Compact bone, titanium, cobalt-chrome, stainless steel

   2) Titanium, compact bone, cobalt-chrome, stainless steel

   5) Titanium, compact bone, stainless steel, cobalt-chrome

   4) Compact bone, titanium, stainless steel, cobalt-chrome

    

   The correct order of modulus of elasticity is as follows in Gpa (psi x 106 ):

   Compact bone: 21 (3)

   Titanium: 96 (14)

   Stainless Steel: 193 (28)

   Cobalt-Chrome: 235 (34)

   Correct Answer: Compact bone, titanium, stainless steel, cobalt-chrome

    

    

5. (1001) Q1-1308:

   In a patient with a previous compression hip screw in place at the time of total hip arthroplasty, what precautionary measures should be undertaken after hardware removal to prevent a periprosthetic fracture:

    

   1) Cemented femoral component with cement augmentation of the screw holes, full weight bearing

   3) Regular femoral prosthesis with toe touch weight bearing for 6 weeks

   2) Plate augmentation with circlage wires, protected weight bearing

   5) Bypassing the last screw hole with a cemented femoral component by two cortical diameters, protected weight bearing

   4) Cortical strut allograft, protected weight bearing

    

   Stress risers are generated when a screw is removed from the femur, weakening the bone for at least 4 weeks. Larger defects (50% of the cortical width) can reduce torsional strength up to 44%. Bypassing the defect by two cortical diameters with a cemented stem doubles the bone?s strength.Correct Answer: Bypassing the last screw hole with a cemented femoral component by two cortical diameters, protected weight bearing

    

    

6. (1002) Q1-1309:

   Which of the following radiographic changes can be expected after placement of a fully porous-coated cobalt chrome femoral stem:

    

   1) Proximal femoral osteopenia

   3) Radiolucency around the acetabular cup

   2) Distal femoral osteopenia

   5) Osteopenia adjacent to the entire femoral component

   4) Increased mineralization proximally

    

   The most severe stress shielding occurs with an extensively porous-coated, chrome-cobalt stem. This occurs as the load is transferred from the hip joint to the proximal femur. The load that was previously carried by the hip joint is now shared by the implant. This change will lead to remodeling of the proximal femur, resulting in a decreased density and thinning of the proximal portion of the femur. In a group of patients characterized as having severs stress shielding based on plain radiographs, no adverse effects were noted n terms of hip scores, presence of osteolysis, or need for revision.Correct Answer: Proximal femoral osteopenia

    

    

    

7. (1003) Q1-1310:

   Noncircumferential porous coating has been shown to lead to which adverse affect:

    

   1) Increased rates of infection

   3) Increased rates of distal osteolysis and late femoral loosening

   2) Increased rates of stress shielding

   5) Increased rates of acetabular osteolysis and late cup loosening

   4) Increased rates of thigh pain

    

   Noncircumferential porous coating may allow a pathway for particulate debris (polywear) to the distal part of the stem, promoting osteolysis.Correct Answer: Increased rates of distal osteolysis and late femoral loosening

    

    

    

8. (1004) Q1-1311:

   Position for hip arthrodesis is best stated as:

    

   1) Neutral abduction/adduction, 20° to 30° flexion, neutral internal/external rotation

   3) 20° abduction, 20° to 30º flexion, neutral internal/external rotation

   2) Neutral abduction/adduction, full extension, neutral internal/external rotation

   5) Neutral abduction/adduction, 45° flexion, neutral internal/external rotation

   4) Neutral abduction/adduction, 20° to 30° flexion, 15° to 20° internal rotation

    

   The favored position of arthrodesis is 20° to 30º flexion, neutral (or minimal adduction) adduction/abduction, and neutral internal/external rotation (can be slight external rotation). Insufficient flexion makes sitting difficult, while too much will make standing difficult due to increased lumbar lordosis. Abduction and internal rotation should be avoided.Correct Answer: Neutral abduction/adduction, 20° to 30° flexion, neutral internal/external rotation

    

    

    

9. (1005) Q1-1312:

   The position putting a total hip arthroplasty most at risk for an anterior dislocation is:

    

   1) Flexion, adduction, internal rotation

   3) Extension, adduction, external rotation

   2) Flexion, abduction, internal rotation

   5) Flexion, adduction, external rotation

   4) Extension, adduction, internal rotation

    

   The most common direction for dislocation of a total hip arthroplasty is posterior. It may be associated with a posterior approach, poor technique, and/or previous surgery. Posterior dislocations can be accentuated by placing the hip in flexion, adduction, and internal rotation (i.e., rising from a low-seated chair). Less common anterior dislocations can occur after an anterior approach or with anteversion of the cup or femoral component (or both). The position for dislocation is accentuated by extension, adduction, and external rotation.Correct Answer: Extension, adduction, external rotation

    

    

10. (1006) Q1-1313:

    Loosening of a cemented metal backed polyethylene acetabular component occurs at which of the following junctions:

     

    1) The cement bone interface

    3) The metal polyethylene interface as a result of micromotion

    2) The cement metal interface

    5) Both the cement-bone and cement-metal interface

    4) Result of fracture and dissolution through the structure of the cement itself

     

    Autopsy studies have shown that the loosening of cemented components occurs at the cement bone interface. This loosening occurs first at the periphery and proceeds toward the dome. This is most likely an extension of the pseudocapsule. The bone resorption at the cement-bone interface appears to be a result of a response to polyethylene debris.Correct Answer: The cement bone interface

     

     

     

11. (1007) Q1-1314:

    Placement of a screw in the anterior superior quadrant of the acetabulum will place which structure at risk:

     

    1) Internal iliac artery

    3) Common iliac vein

    2) Bladder

    5) Common iliac artery

    4) External iliac vein

     

    Placement of screws in the acetabular cup in the anterior superior or anterior inferior quadrant is not advised due to the proximity of the external iliac vein and the obturator artery, respectively.Correct Answer: External iliac vein

     

     

     

12. (1008) Q1-1315:

    During revision surgery for a total hip arthroplasty, the accepted standard for the presence of an infection on frozen tissue histological analysis is:

     

    1) Five mononuclear cells per high-powered field

    3) Five polymorphonuclear cells per high-powered field

    2) Ten mononuclear cells per high-powered field

    5) One bacterium per high-powered field

    4) Ten polymorphonuclear cells per high-powered field

     

    Frozen section analysis is important in revision surgery to determine why a component has become loose. Ten polymorphonuclear cells (PMNs) per high-powered field lowers the sensitivity for infection but does not reduce the specificity to diagnose an infection. Five PMNs per high-powered field is the current standard that is accepted as diagnostic for an infection. Mononuclear cells can be present in the face of aseptic loosening or polywear disease. PMNs are diagnostic of a biologic infectious response.Correct Answer: Five polymorphonuclear cells per high-powered field

     

     

     

13. (1009) Q1-1316:

Which of the following is not a significant risk factor for the development of heterotopic ossification:

 

1) Hypertrophic osteoarthritis

3) Posttraumatic arthritis

2) Ankylosing spondylitis

5) Previous formation of heterotopic ossification

4) Previous osteonecrosis

 

Heterotopic ossification is seen more in men than in women. It is also more common in patients with hypertrophic osteoarthritis, posttraumatic arthritis, ankylosing spondylitis, longer operative times, and especially previous heterotopic bone formation.

Anterior and lateral approaches have a higher incidence.Correct Answer: Previous osteonecrosis

 

 

Long stemmed tibial components for revision total knee arthroplasty are not cemented for which of the following reasons:

 

1) Extensive stress shielding

3) Infection risk

2) Difficulty in removal

5) Hypotension with insertion

4) Asymmetric wear

 

A cemented tibial stem will stress shield the tibial cortex for the entire length of the stem. Proximal bone resorption will occur as a result.Correct Answer: Extensive stress shielding

 

 

 

1. (1011) Q1-1318:

   Unicompartmental arthroplasty is contraindicated in which patient:

    

   1) A patient with osteonecrosis of medial condyle

   3) A patient with rheumatoid arthritis concentrated in the medial compartment

   2) A patient with osteoarthritis of medial condyle

   5) A patient with prior patellectomy with medial compartment osteoarthritis

   4) A patient with posttraumatic arthritis of the medial tibial plateau

    

   Unicompartmental arthroplasty is a viable alternative to total knee arthroplasty in select patients. The most common indications for unicompartmental replacement are osteonecrosis, osteoarthritis, and posttraumatic arthritis isolated to one compartment.

   Patients with prior patellectomies may do well with a unicompartmental replacement. Contraindications to unicompartmental replacement are inflammatory arthritides (i.e., rheumatoid arthritis) due to whole knee involvement, young patients unwilling to stop work or sport, or a history of recent infection.Correct Answer: A patient with rheumatoid arthritis concentrated in the medial compartment

    

    

    

2. (1012) Q1-1319:

   If a metal-backed tibial component is used for total knee arthroplasty, what is the minimum thickness of polyethylene to be used to prevent accelerated wear:

    

   1) 4 mm to 6 mm

   3) 8 mm to 10 mm

   2) 12 mm to 14 mm

   5) Whatever polyethylene thickness balances the knee correctly

   4) 10 mm to 12 mm

    

   If a metal-backed tibial component is used in total knee arthroplasty, a minimum component thickness of 8 mm to 10 mm of polyethylene should be used. Contact stresses increase dramatically and non-linearly as a thickness of 6 mm or less is used.Correct Answer: 8 mm to 10 mm

    

    

    

3. (1013) Q1-1320:

Which of the following is not a contraindication for high tibial osteotomy to treat medial compartment arthritis:

 

1) Obesity

3) Rheumatoid arthritis

2) Age greater than 65

5) A young patient unwilling to stop high activity occupation

4) Prior medial and lateral menisectomy

 

High tibial osteotomy can be performed in younger individuals with isolated medial compartment disease. High impact an excessive loading activities can be tolerated after osteotomy, whereas these activities are prohibited with prosthetic joint replacement. Contraindications include those older than 65 years of age, inflammatory arthritis, and previous medial and lateral menisectomies, as they would be better served with total joint arthroplasty. Obesity is associated with early failure in high tibial osteotomy.Correct Answer: A young patient unwilling to stop high activity occupation

 

 

In preoperative evaluation for total knee arthroplasty, a patient is seen to have three previous incisions over the anterior knee. Two are longitudinal, 2.5 cm apart over the anterior aspect of the patella. One is transverse. All incisions are healed. Which incision should be used to decrease the likelihood of skin necrosis:

 

1) The medial most longitudinal incision

3) The transverse incision as the skin will slough with either of the previous longitudinal incisions

2) The lateral most longitudinal incision

5) The longitudinal incision that will allow for best exposure

4) A new midline incision between the two longitudinal incision

 

Prior surgical incisions are a potential for post-operative wound problems. Usually, the lateral most longitudinal incision is best used. A large lateral flap has been associated with postoperative wound problems. The lateral flap has shown less oxygen concentration in studies, therefore, making a small lateral flap is preferred. Transverse incisions can be crossed with relative impunity if the angle is greater than 60º.Correct Answer: The lateral most longitudinal incision

 

 

 

1. (1015) Q1-1322:

   A patient who underwent a posterior stabilized total knee arthroplasty 10 months ago has new complaints of knee pain and popping. This pain was exacerbated with climbing stairs and rising from a chair. An audible and palpable clunk is heard with terminal extension. Range of motion is from 0° to 110º, and there is no evidence of instability with examination. A pop is felt with active extension in the terminal 15° to 30º of motion. The best treatment is:

    

   1) Revision arthroplasty

   3) Revision to a condylar constrained type prosthesis

   2) Nonsteroidal anti-inflammatory medicines

   5) Patellectomy

   4) Arthroscopic debridement or open revision of the patellar component

    

   Patellar "clunk" syndrome is a type of peripatellar fibrous hyperplasia characterized by a discrete suprapatellar fibrous nodule. This nodule lodges into the femoral component intercondylar notch dung flexion and displaces with an audible, often painful, clunk with extension. This condition is isolated to posterior stabilized femoral components, and not evident in posterior cruciate ligament retaining prostheses. Initial treatment is physical therapy, which is sometimes successful. Most commonly, either an arthroscopic debridement or open revision of the patellar component and fibrous hyperplasia is needed for resolution of symptoms.Correct Answer: Arthroscopic debridement or open revision of the patellar component

    

    

    

2. (1016) Q1-1323:

A patient has a displaced supracondylar femur fracture 6 cm proximal to a well-fixed, posterior stabilized component. This knee was asymptomatic prior to fracture. Treatment should include which of the following:

 

1) Cast bracing

3) Revision to a long stemmed femoral component

2) Traction

5) Plate fixation (Dynamic Condylar Screw or fixed angle blade) with retention of femoral component

4) Retrograde nail fixation with retention of femoral component

 

In fractures above a well-fixed femoral component, all attempts should be made to retain the component. The fracture must be aligned correctly and stabilized to permit early range of motion of the extremity. Casting or traction will likely result in loss of motion, while early range of motion without internal fixation can lead to malunion. Posterior stabilized femoral components with closed housing prohibit retrograde intramedullary nailing.Correct Answer: Plate fixation (Dynamic Condylar Screw or fixed angle blade) with retention of femoral component

 

 

Resection of too little distal femur will have what effect on the "flexion/extension gap" with regard to ligamentous balancing:

 

1) Increase flexion gap (loose in flexion)

3) Decrease flexion gap (tight in flexion)

2) Increase extension gap (recurvatum)

5) Will not affect gap if appropriate polyethylene is used

4) Decrease extension gap (flexion contracture)

 

The extension gap is created with the distal femur and the proximal tibial cuts. The flexion gap is created with the posterior femur and the proximal tibial cuts. Altering the tibial cut will alter the flexion and extension gaps equally. Altering the distal femur cut alone will have an effect exclusively on the extension gap.Correct Answer: Decrease extension gap (flexion contracture)

 

 

 

1. (1018) Q1-1325:

   Excessive internal rotation of the tibial component should be avoided because of which resultant effect:

    

   1) Net internal rotation of tibial tubercle, increased wear

   3) Net internal rotation of the leg causing the patient to in-toe

   2) Net external rotation of tibial tubercle, patellar subluxation

   5) Will likely have no effect if ligaments are balanced

   4) Net external rotation of the leg causing thigh pain

    

   Internal rotation of the tibial component will cause external rotation of the tibial tubercle with an increased Q angle. An increased Q angle will cause an increase in patellar subluxation force and maltracking.Correct Answer: Net external rotation of tibial tubercle, patellar subluxation

    

    

    

2. (1019) Q1-1326:

A 65-year-old patient presents with complaints of giving way in her knee. She underwent a total knee arthroplasty 2 years ago. Intraoperatively, the medial collateral ligament was disrupted, but repaired primarily. This has gone on to give the patient instability when she ambulates. Physical therapy and bracing have not helped. On radiographic examination, the components are well fixed and in appropriate position. Physical examination reveals a range of motion from 0° to 130° with no anteroposterior laxity. There is laxity at 0°, 45°, and 90º to valgus stress. Appropriate treatment should now consist of:

 

1) Ipsilateral semitendinosis and gracillis autograft reconstruction of the medial collateral ligament

3) Allograft Achilles tendon reconstruction of the medial collateral ligament

2) Contralateral semitendinosis and gracillis autograft reconstruction of the medial collateral ligament

5) Revision to a constrained-condylar type prosthesis

4) Contralateral bone-patellar-tendon autograft reconstruction of the medial collateral ligament

 

This patient has an incompetent medial collateral ligament throughout range of motion. If the disruption is caught early enough in surgery, primary repair can be made with satisfactory results. Ligamentous reconstruction without conversion to a constrained prosthesis with varus/valgus stability has been shown to be ineffective.Correct Answer: Revision to a constrained-condylar type prosthesis

 

 

When comparing the subvastus approach to the medial parapatellar approach to the knee for total knee arthroplasty, which of the following statements is true:

 

1) Range of motion is better long term for the subvastus approach.

3) The subvastus approach is more technically difficult and exposure is more difficult than a medial parapatellar approach.

2) The need for lateral retinacular release is more common in the medial parapatellar approach.

5) The subvastus approach is associated with more wound complications than the medial parapatellar approach.

4) Patella subluxation is more common in the medial parapatellar approach.

 

The subvastus approach is associated with less wound complications than the medial parapatellar incision. The skin can be tight in flexion with a medial parapatellar incision; however, this is not common with the subvastus incision. In a series of 28 bilateral knees, Ritter and colleagues, compared a subvastus approach with the traditional medial parapatellar approach. Complications and range of motion between sides were equal. They did note, however, that exposure was much more difficult with the subvastus approach.Correct Answer: The subvastus approach is more technically difficult and exposure is more difficult than a medial parapatellar approach.

 

 

 

1. (1021) Q1-1328:

   The most common extensor mechanism complication in total knee arthroplasty is:

    

   1) Patella fracture

   3) Patellar clunk

   2) Patellar instability

   5) Patellar tendon rupture

   4) Quadriceps tendon rupture

    

   Patellar instability is the most frequent extensor mechanism complication. Most often it is manifested as subluxations or dislocation. Sometimes abnormal component wear or patella fractures are a result of abnormal patellar tracking. These consequences are usually the inevitable result of component malposition, limb malalignment, improper patellar preparation, improper component design, or trauma. Each of these mechanisms may be at play whether or not the patella is resurfaced.Correct Answer: Patellar instability

    

    

    

2. (1022) Q1-1329:

A patient with a 35º valgus deformity and a 20° flexion contracture of the knee undergoes primary total knee arthroplasty successfully. In the recovery room, the patient is seen to have no dorsiflexion of the foot or toes and numbness over the dorsum of the foot. There is no pain with passive range of motion of the foot and calf compartments are soft. The next appropriate step is:

 

1) Re-observation in 30 minutes, leg elevation, and ice

3) Fasciotomies of the leg

2) Bring the patient back to the operating room to explore the peroneal nerve

5) Strict extension splinting, removal of the constrictive dressings

4) Remove the dressings and flex the leg

 

Peroneal palsy after total knee arthroplasty is a rare but significant complication after total knee arthroplasty. Incidence is higher in revision surgeries and those with flexion and valgus contractures. Postoperative constrictive dressings and hematomas may also cause or contribute to nerve ischemia or injury. Treatment of the peroneal palsy should initially be nonoperative. Removal of constrictive dressings and flexion of the knee will relieve pressure on the peroneal nerve. AFO will help with ambulation. Surgical exploration of the nerve is of no value and may exacerbate injury.Correct Answer: Remove the dressings and flex the leg

 

 

A 70-year-old patient with a past history of prostate cancer treated with pelvic irradiation wishes to have a total hip arthroplasty for severe unilateral hip osteoarthritis. What is the most likely consequence of cementless fixation of the acetabular cup:

 

1) Fracture

3) Thromboembolic phenomenon

2) Bleeding

5) Aseptic loosening of the acetabular cup

4) Abductor weakness

 

Forty-four percent of patients in one study showed failure of fixation to bone of the acetabular cup after previous pelvic irradiation. This study demonstrates the high failure of porous ingrowth in the presence of previous irradiation in the acetabulum. It is therefore recommended to cement the acetabular cup or to use a protrusio-type cage with cement in this subset of patients. This is secondary to the loss of vascularity and viability of the bone caused by irradiation.Correct Answer: Aseptic loosening of the acetabular cup

 

 

 

1. (1616) Q1-2010:

   In patients with osteoarthritis, mechanical forces induce changes in the form and structure of many biologic materials including bone and cartilage. This effect is known as:

    

   1) Wolffs law

   3) Hilgenreiners law

   2) Kochs postulate

   5) Evans law

   4) Singhs index

    

   According to Wolffs law, stresses and strains contribute to bone density, strength, and ultimate shape of bone and internal trabecular arrangement.Correct Answer: Wolffs law

    

    

2. (1617) Q1-2011:

   The reduction mechanism of venous thromboembolism from epidural anesthesia in total joint replacement is:

    

   1) Inhibition of platelet adhesion

   3) Sympathetic effect of epidural blockage

   2) Stimulation of endothelial fibrinolysis

   5) Increased lower extremity blood flow

   4) Decreased lower extremity blood flow

    

   The sympathetic effect of epidural blockage results in increased lower extremity blood flow, which is responsible for the reduction of venous thromboembolism by mitigating the adverse effects of stress.Correct Answer: Sympathetic effect of epidural blockage

    

    

3. (1618) Q1-2012:

Which of the following is not a clinical sign of pulmonary embolism:

 

1) Pleuritic chest pain and pleural rub

3) Tachypnea

2) Bradycardia

5) Pleural rub

4) Dyspnea

 

Tachycardia, as well as pleuritic chest pain, pleural rub, tachypnea, and dyspnea, are the most common clinical symptoms of pulmonary embolism. Bradycardia is not a clinical sign of pulmonary embolism.Correct Answer: Bradycardia

 

In total joint replacement, osteolysis that results in bone loss and bone resorption is caused by:

 

1) Breakdown of polymethylmethacrylate

3) Metal debris

2) Polyethylene debris

5) Allergic reaction to titanium

4) Hydroxyapatite

 

Osteolysis, which results in bone loss and bone resorption, is caused by polyethylene debris.Correct Answer: Polyethylene debris

 

 

1. (1620) Q1-2014:

   Bone grafts (autograft) used to restore bone stock in total joint replacements are the result of what biologic process:

    

   1) Osteogenesis

   3) Osteoconduction

   2) Osteoinduction

   5) Osteogenesis, osteoinduction, and osteoconduction

   4) Osteogenesis and osteoinduction

    

   Bone formation from osteoblasts (osteogenesis), recruiting host mesenchymal cells and differentiating them into bone-forming cells (osteoinduction), and the ingrowth of blood vessels and osteoprogenitor cells (osteoinduction) are important in influencing bone graft function.Correct Answer: Osteogenesis, osteoinduction, and osteoconduction

    

    

2. (1621) Q1-2015:

   Ceramics are used as an osteoconductive bone-graft material. The optimal pore size is:

    

   1) 50 [mu]m to 100 [mu]m

   3) 150 [mu]m to 500 [mu]m

   2) 100 [mu]m to 150 [mu]m

   5) 800 [mu]m to 1000 [mu]m

   4) 500 [mu]m to 700 [mu]m

    

   The optimal pore size of osteoconductive ceramics is between 150 [mu]m to 500 [mu]m. Smaller or larger pore sizes are not as effective.Correct Answer: 150 [mu]m to 500 [mu]m

    

    

3. (1622) Q1-2016:

The American College of Cardiology recommends that a patient wait how long after a myocardial infarction before undergoing a total hip replacement:

 

1) 3 weeks

3) 3 months

2) 6 weeks

5) 1 year

4) 6 months

 

The American College of Cardiology presently recommends that a patient wait 6 weeks after a myocardial infarction before undergoing a total hip replacement. There is increased risk of complication if a total hip replacement is performed before 6 weeks.Correct Answer: 6 weeks

 

Patients with rheumatoid arthritis must be radiologically evaluated for this condition:

 

1) Odontoid abnormality

3) C 2 - C 3 subluxation

2) C 1 - C 2 subluxation

5) C 4-C 5 subluxation

4) C 3 - C 4 subluxation

 

Patients with rheumatoid arthritis must be carefully evaluated for cervical spine subluxation, which is characterized by atlantoaxial translation on flexion-extension views of the cervical spine.Correct Answer: C 1 - C 2 subluxation

 

 

1. (1624) Q1-2018:

   In hypotensive total joint replacement surgery, the mean blood pressure is kept at:

    

   1) 50 mm Hg

   3) 70 mm Hg

   2) 60 mm Hg

   5) 90 mm Hg

   4) 80 mm Hg

    

   Using a combination of volatile anesthetics, narcotics, and vasodilators, the mean blood pressure is kept at 60 mm Hg during hypotensive total joint replacement surgery. This is the lowest pressure that can be obtained and still be within safety parameters.Correct Answer: 60 mm Hg

    

    

2. (1625) Q1-2019:

   The optimal position of a patientâs knee during total knee replacement surgery is:

    

   1) 3° of anatomic valgus

   3) 7° of anatomic valgus

   2) 5° of anatomic valgus

   5) Neutral

   4) 8° of anatomic valgus

    

   The optimal position of a patientâs knee during total knee replacement surgery is 7° of anatomic valgus as measured between the mechanical and anatomic axis. More or less valgus is not optimal.Correct Answer: 7° of anatomic valgus

    

    

3. (1626) Q1-2020:

The optimal position for the acetabular cup during total hip replacement surgery is:

 

1) Neutral version

3) 15° anteversion

2) 5° anteversion

5) 45° anteversion

4) 30° anteversion

 

The optimal cup position of a patientâs hip during total hip replacement surgery is 15° of cup anteversion as measured on a lateral radiograph of the groin. More or less anteversion is not optimal. The femoral stem version needs to be part of the equation.Correct Answer: 15° anteversion

 

Gallium-67 citrate used in scanning techniques can result in increased gallium-67 localization in:

 

1) Infection

3) Aseptic loosening

2) Fracture

5) Infection, fracture, and aseptic loosening

4) Infection and fracture

 

Although increased gallium-67 citrate localization is found in infection, there are also significant false-positive results in fracture and aseptic loosening. It is more specific for infection but increased localization is seen in all three conditions.Correct Answer: Infection, fracture, and aseptic loosening

 

 

1. (1628) Q1-2022:

   The most specific scanning method to detect infection in total joint replacement is:

    

   1) White blood cell scanning

   3) Sequential technetium bone scans

   2) Technetium bone scanning

   5) A combination of white blood cell scanning and technetium bone scanning

   4) Sequential gallium-67 citrate scans

    

   White blood cell scanning combined with technetium bone scanning is more specific for the diagnosis of infection than sequential technetium bone scans or sequential gallium-67 citrate scans.Correct Answer: A combination of white blood cell scanning and technetium bone scanning

    

    

2. (1629) Q1-2023:

   Outcomes, as opposed to traditional results, are more reliable because they include:

    

   1) Measured and recorded clinical results

   3) Social consequences and political consequences

   2) Economic consequences only

   5) Measured and recorded clinical results, economic consequences, and social consequences

   4) Political consequences only

    

   The study of outcomes is characterized by broadening the definition of surgical results from strictly clinical to the economic, social, and political consequences. All of these factors must be considered in analyzing surgical results in the study of outcomes.Correct Answer: Measured and recorded clinical results, economic consequences, and social consequences

    

    

3. (1630) Q1-2025:

The anterolateral (Watson-Jones) approach to the hip dissects in an interval between:

 

1) The gluteus medius and gluteus minimus

3) The tension fascia lata muscles and rectus femoris

2) The gluteus medius and tensor fascia lata muscles

5) The gluteus maximus

4) The gluteus medius and quadratus femoris

 

The anterolateral exposure dissects an interval between the gluteus medius and tensor fascia lata muscles to preserve the superior gluteal innervation of the tensor fascia muscles. The other intervals are not used in the anterolateral approach.Correct Answer: The gluteus medius and tensor fascia lata muscles

 

 

 

1. Limited proximal acetabular exposure

   3) Slower abductor rehabilitation

   2) Increased incidence of heterotopic ossification

   5) Limited proximal acetabular exposure, increased heterotopic ossification, and slower abductor rehabilitation

   4) Increased heterotopic ossification and slower abductor rehabilitation

    

   Limited proximal acetabular exposure, increased incidence of heterotopic ossification, and limp secondary to weak abductors are commonly associated with the direct lateral approach. The dislocation rate is less than with a posterior approach.Correct Answer: Limited proximal acetabular exposure, increased heterotopic ossification, and slower abductor rehabilitation

    

    

   1. (1632) Q1-2027:

      When using the direct lateral (modified Hardinge) approach to the hip, the incidence of total hip dislocation is:

       

      1) 2%

      3) 0.3%

      2) 0.1%

      5) 4%

      4) 3%

       

      In a retrospective review of 770 consecutive primary total hip arthroplasties, the dislocation rate was 0.3%. Higher dislocation rates are associated with the posterior approach.Correct Answer: 0.3%

       

       

   2. (1633) Q1-2028:

      When using the direct lateral (modified Hardinge) approach for total hip replacement, what percentage of patients will have a moderate or severe limp at 2 years postoperative:

       

      1) 0.5%

      3) 5%

2. 1%

   5) 15%

   4) 10%

    

   According to Mulliken and colleagues, the incidence of moderate or severe limp at 2 years postoperative is 10%. This is a significant incidence, but the dislocation rate is much lower than the other approaches to the hip.Correct Answer: 10%

    

    

   1. (1634) Q1-2029:

   The posterior approach to the hip has the following advantage(s) over the direct lateral approach when performing total hip arthroplasty:

    

   1. Easy exposure

3. Decreased heterotopic ossification

1. Decreased operative time

   5) Decreased operative time and decreased heterotopic exposure

   4) Easy exposure, decreased operative time, and decreased heterotopic ossification

    

   Easy exposure, decreased operative time, and decreased heterotopic ossification are advantages of using the posterior approach. It is, however, important to note that the posterior approach is associated with a higher rate of dislocation.Correct Answer: Easy exposure, decreased operative time, and decreased heterotopic ossification

    

    

    

   1) Gluteus medius

   3) Gluteus minimus

   2) Gluteus maximus

   5) External rotators

   4) Tensor fascia lata

    

   The posterior approach splits the gluteus maximus. The remainder of the approach releases the short external rotators followed by a posterior capsulotomy, which then allows entry into the posterior hip joint.Correct Answer: Gluteus maximus

    

    

   1. (1636) Q1-2031:

      The trochanteric slide osteotomy involves:

       

      1) Osteotomy of anterior greater trochanter bone

      3) Osteotomy of anterior greater trochanter bone and keeping the gluteus medius in continuity

      2) Keeping the gluteus medius and vastus lateralis in continuity

      5) Osteotomy of anterior greater trochanter bone and keeping the gluteus medius and vastus lateralis in continuity

      4) Osteotomy of anterior greater trochanter bone and keeping the vastus lateralis in continuity

       

      The trochanteric slide osteotomy is a modification of the Charnley transtrochanteric approach. The trochanteric slide osteotomy was developed because of concerns with trochanteric reattachment and possible nonunion of the trochanteric fragments. The trochanteric slide osteotomy also improves visualization in difficult primary arthroplasties, as well as in revision arthroplasty.Correct Answer: Osteotomy of anterior greater trochanter bone and keeping the gluteus medius and vastus lateralis in continuity

       

       

   2. (1637) Q1-2032:

      The vastus slide utilizes a:

       

      1) Modified anterior approach to the hip joint

      3) The vastus lateralis is reflected off the proximal femur from its posterior attachment to the lateral intermuscular septum.

      2) A trochanteric osteotomy

      5) Posterior approach to the hip

      4) Modified anterior approach to the hip joint and trochanteric osteotomy

       

      The vastus slide is a modified lateral approach to the hip and does not involve a trochanteric osteotomy. The vastus slide provides good exposure of the proximal femur in revision hip surgery but is not recommended for complicated acetabular reconstruction.Correct Answer: The vastus lateralis is reflected off the proximal femur from its posterior attachment to the lateral intermuscular septum.

       

       

   3. (1638) Q1-2033:

   To perform an extended trochanteric osteotomy:

    

   1) The posterior approach is extended distally along the posterior border of the gluteus medius.

   3) The gluteus maximus muscle is detected.

   2) The posterior portion of the vastus lateralis is identified.

   5) All of the above

   4) The interval between the posterior vastus and gluteus maximus is developed.

    

   In addition to all of the above steps, the lateral-third of the proximal femur is osteotomized using an oscillating saw or burr.Correct Answer: All of the above

    

    

    

   1) Easier access to bone-cement interface

   3) Better exposure of acetabulum

   2) Decreased operative time

   5) Easier access to bone-cement interface and decreased operative time

   4) Easier access to bone-cement interface, decreased operative time, and better exposure of acetabulum

    

   In addition to the answers above, there is more predictable healing of the osteotomized fragment, neutral recovery of femoral canal, and better tensioning of the abductors with distal advancement.Correct Answer: Easier access to bone-cement interface, decreased operative time, and better exposure of acetabulum

    

    

   1. (1640) Q1-2035:

      The anatomy of the hip provides considerable rotation in:

       

      1) One anatomic plane

      3) Three anatomic planes

      2) Two anatomic planes

      5) Six anatomic planes

      4) Four anatomic planes

       

      The anatomy of the hip provides rotation in three anatomic planes (sagittal, coronal, and transverse). To understand the hip anatomy and rotation, one must consider all three anatomical planes.Correct Answer: Three anatomic planes

       

       

   2. (1641) Q1-2036:

      Most patients have a hip flexion-extension arc of:

       

      1) 100° to 110°

      3) 120° to 140°

      2) 110° to 120°

      5) 110° to 140°

      4) 130° to 150°

       

      Most patients have a flexion-extension arc of 120° to 140°, an abduction-adduction arc of 60° to 80°, and an internal-external rotation arc of 60° to 90°. The vast majority of patients have a flexion-extension arc of 120° to 140°.Correct Answer: 120° to 140°

       

       

   3. (1642) Q1-2037:

   Femoral implants with greater anteversion will impinge (trochanter against the pelvis):

    

   1) Posteriorly in extension with lesser external rotation

   3) Posteriorly in flexion with lesser external rotation

   2) Anteriorly in extension with lesser external rotation

   5) Posteriorly in extension with lesser internal rotation

   4) Anteriorly in flexion with lesser external rotation

    

   Proximal femoral implants with greater anteversion impinge trochanter against pelvis with lesser external rotation, whereas proximal femoral implants with lesser anteversion tend to impinge anteriorly in flexion with lesser internal rotation.Correct Answer: Posteriorly in extension with lesser external rotation

    

    

    

   1) 40° of flexion-extension and the same internal-external rotation/abduction-adduction

   3) 70° of flexion-extension and the same internal-external rotation/abduction-adduction

   2) 55° of flexion-extension and the same internal-external rotation/abduction-adduction

   5) 90° of flexion-extension and the same internal-external rotation/abduction-adduction

   4) 80° of flexion-extension and the same internal-external rotation/abduction-adduction

    

   Level walking requires approximately 50° to 60° of flexion-extension with a relatively small amount of internal-external rotation or abduction-adduction.Correct Answer: 55° of flexion-extension and the same internal-external rotation/abduction-adduction

    

    

   1. (1644) Q1-2039:

      To put on a pair of shoes, the arc of motion required in the hip joint is:

       

      1) 100°

      3) 140°

      2) 130°

      5) 180°

      4) 170°

       

      The total motion of the three anatomic planar arcs of the hip is 240° to 300°. The arc of motion required to put on a pair of shoes is 160° to 170°.Correct Answer: 170°

       

       

   2. (1645) Q1-2040:

      Recent mathematical modeling of hip joint forces during activities of daily living relative to body weight show elevations by a factor of:

       

      1) 1 to 2

      3) 2 to 4

      2) 2 to 3

      5) 4 to 6

      4) 3 to 5

       

      Recent mathematical modeling studies show that hip joint forces are approximately 2 to 4 times body weight. The hip joint forces will increase with strenuous activities, especially exercise.Correct Answer: 2 to 4

       

       

   3. (1646) Q1-2041:

      Implantation of a total hip prosthesis can significantly alter hip forces. The lowest forces occur at the:

       

      1) Anatomic hip center

      3) Superior anatomic hip center

      2) Lateral anatomic hip center

      5) Inferior anatomic hip center

      4) Posterior anatomic hip center

       

      The lowest forces occur at the anatomic hip center and increase farther away from the anatomic center. Therefore, the forces increase in all directions from the anatomic center.Correct Answer: Anatomic hip center

       

       

   4. (1647) Q1-2042:

      Implantation of a total hip prosthesis can significantly alter hip forces. The greatest increase in hip forces occur at the:

       

      1) Anatomic hip center

      3) Superior anatomic hip center

      2) Lateral anatomic hip center

      5) Inferior anatomic hip center

      4) Posterior anatomic hip center

       

      The highest forces occur when the total hip replacement is lateral to the anatomic hip center. The forces in all of the other directions are decreased compared to the lateral anatomic hip center.Correct Answer: Lateral anatomic hip center

       

   5. (1648) Q1-2043:

      When implanting a total hip prosthesis, the greatest strains occur at what part of the femoral implant:

       

      1. Neck of the femoral anatomy

         3) Calcar

         2) Greater trochanteric

         5) Tip of the prosthesis

         4) Midportion of the prosthesis

          

         Strains are reduced in the calcar by as much as 90%, but the tip of the prosthesis experiences increased strain. The neck of the femoral anatomy, greater trochanter area, and midportion of the prosthesis experience strain but not as great as the tip of the prosthesis.Correct Answer: Tip of the prosthesis

          

          

   6. (1649) Q1-2044:

      What percentage of bone is turned over in the skeleton each year:

       

      1) 5%

2. 15%

1. 10%

   5) 25%

   4) 20%

    

   Bone normally exhibits a turnover rate of roughly 5% of the skeleton each year. A skeleton may exhibit more turnover of bone in certain disease states, but 5% is the average for the normal person.Correct Answer: 5%

    

    

   1. (1650) Q1-2045:

      The stem and mantle is easily extracted in a failed hip arthroplasty if:

       

      1. A circumferential lytic line surrounds the cement mantle

2. Ultrasound equipment is used

1. A circumferential lytic line surrounds the entire prosthesis

   5) One uses an extended trochanteric osteotomy

   4) There is a nonunion of the greater trochanteric osteotomy

    

   If a circumferential lytic line is evident on radiographs, then the bond between the stem and the cement is stronger than the bond between the cement and the bone. In this condition, the stem and mantle are easily extracted as a unit.Correct Answer: A circumferential lytic line surrounds the cement mantle

    

    

   1. (1651) Q1-2046:

   After removing a femoral stem, the best way to prevent fracture of the femur is:

    

   1. Debulk the metaphyseal cement

2. Trochanteric osteotomy

1. Debulk the diaphyseal cement

   5) Use a quarter-inch osteotome

   4) Remove the fibrous layer of tissue

    

   Metaphyseal cement tends to be bulky, and the bone tends to be thin and weak. Initial debulking of the cement with a high-speed burr prevents fracture during attempts at removal of the cement.Correct Answer: Debulk the metaphyseal cement

    

   When removing the cement mantle by cementing a threaded extractor into the mantle, the polymethylmethacrylate (PMMA) can be removed because:

    

   1) The bond of the PMMA to the bone is weak.

   3) The bond of the new PMMA to the old PMMA is weak.

   2) The bond of the PMMA to the bone is strong.

   5) The bond of the new PMMA to the old PMMA is stronger than the bond of PMMA to bone.

   4) The bond of the new PMMA to the old PMMA is strong.

    

   Because the bond of the PMMA to PMMA is stronger then the bond of PMMA to bone, the mantle can be removed in a piecemeal fashion using a threaded extractor. It is often necessary to cement in the extractor multiple times when performing this removal technique.Correct Answer: The bond of the new PMMA to the old PMMA is stronger than the bond of PMMA to bone.

    

    

   1. (1653) Q1-2048:

      Which of the following statements is not true of polymethylmethacrylate (PMMA):

       

      1) PMMA is a grout.

      3) PMMA is strongest in compression.

      2) PMMA is strongest in tension and weakest in compression.

      5) PMMA is strongest in compression and weakest in tension.

      4) PMMA is weakest in tension.

       

      PMMA is a grout and is strong in compression and weak in tension. Tension forces ultimately cause failure of PMMA.Correct Answer: PMMA is strongest in tension and weakest in compression.

       

       

   2. (1654) Q1-2049:

      When making perforations in the cortex of the femur, the perforations should be placed:

       

      1) Posteriorly

      3) Medially

      2) Laterally

      5) Posterior laterally

      4) Anteriorly

       

      Perforations of the femur should be placed anteriorly or anterolaterally. The axis of neutral stress for the proximal femur is in a sagittal plane in the anterior femur.Correct Answer: Anteriorly

       

       

   3. (1655) Q1-2050:

   When making a femoral window, the tip of the new stem must bypass the window by:

    

   1) 1 cm

   3) One femoral diameter

   2) 2 cm

   5) Three femoral diameters

   4) Two femoral diameters

    

   In the femoral window technique and the extended trochanteric technique, the revision stem must bypass the defect in the femoral cortex by at least two femoral diameters to prevent fracture adjacent to the osteotomy.Correct Answer: Two femoral diameters

    

   When making perforations in the cortex of the femur, the perforations should be placed how far apart:

    

   1) 0.5 cm

   3) One hole diameter

   2) 5 cm

   5) Three hole diameters

   4) Two hole diameters

    

   The holes placed in the anterior cortex in this article were 9 mm in diameter. This study showed that placing the hole less than two diameters apart increased the stress in the area between the holes, which could lead to an increased incidence of fracture.Correct Answer: Two hole diameters

    

    

   1. (1665) Q1-2060:

      Reconstructive open methods to obtain femoral neck union of failed femoral neck fractures include all of the following except:

       

      1) Meyers pedicle graft

      3) Valgus intertrochanteric osteotomy

      2) Varus osteotomy

      5) Vascularized tensor fascia latae muscle bone graft

      4) Free vascularized fibulae graft

       

      The Meyers pedicle graft revascularizes the nonunion site. The valgus intertrochanteric osteotomy converts shear forces at the nonunion site to compressive forces and promotes fracture healing. These are the two most common reconstructive open methods. Varus osteotomy is not an open reconstructive method to obtain femoral neck union of a failed femoral neck fracture.Correct Answer: Varus osteotomy

       

       

   2. (1666) Q1-2061:

      When deciding between a hemiarthroplasty and total hip replacement (THR) to serve as a salvage procedure for femoral neck nonunions, one may choose a THR because:

       

      1) There is less risk of dislocation.

      3) It is a smaller procedure.

      2) There is better pain relief.

      5) There is less change of leg length inequality.

      4) Reimbursement is better.

       

      THR provides better pain relief then a hemiarthroplasty, but THR is a bigger procedure with more risk of dislocation. There is an increased chance of leg length inequality with a THR, and reimbursement should never be a deciding factor for a particular surgery.Correct Answer: There is better pain relief.

       

       

   3. (1667) Q1-2062:

   Which of the following is the preferred method for treating intertrochanteric nonunions in young patients:

    

   1) Hemiarthroplasty

   3) Blade plate and autogenous bone graft

   2) Total hip replacement (THR)

   5) Varus osteotomy

   4) Gamma nail

    

   Blade plate and autogenous bone graft is the preferred method for treating intertrochanteric nonunions in young patients. The femoral head will retain its vascularity and remain viable, so solutions such as hemiarthroplasty and THR should be reserved for older patients.Correct Answer: Blade plate and autogenous bone graft

    

   Which of the following is the best treatment for older patients with a failed intertrochanteric fracture and bone loss near the lesser trochanter:

    

   1) Gamma nail

   3) Standard total hip replacement

   2) Blade plate and autogenous bone graft

   5) Calcar replacement implant with long stem

   4) Calcar replacement implant

    

   A calcar replacement implant is required to provide leg length and gain hip stability, and a long-stem implant is often required to bypass screw holes in the femur.Correct Answer: Calcar replacement implant with long stem

    

    

   1. (1669) Q1-2064:

      Which of the following factors is of least importance when considering the preoperative planning of a revision total knee replacement:

       

      1) Bone loss and bone defects

      3) Integrity of the collateral ligaments

      2) Integrity of the extensor mechanism

      5) Bone density

      4) Soft tissue envelope including the skin

       

      Adequate imaging and planning must include an assessment of the size and location of bone defects, the integrity of the extensor mechanism collateral ligaments, and the soft tissue envelope including the skin.Correct Answer: Bone density

       

       

   2. (1670) Q1-2065:

      According to Enghâs classification of bone defects in failed total knee arthroplasty, type 2 defects usually require:

       

      1) Cement filling

      3) Augmented femoral or tibial components

      2) Morcelized bone graft

      5) Hinge component

      4) Structural bone graft

       

      Cement and morcelized bone graft are usually reserved for type 1 defects. Type 2 defects usually require an augmented femoral or tibial component, whereas type 3 defects require a structural bone graft and often a hinged component.Correct Answer: Augmented femoral or tibial components

       

       

   3. (1671) Q1-2066:

   When using a structural bone graft in type 3 bone defects (Enghâs classification), which of the following statements is incorrect:

    

   1) Step cut the bone allograft.

   3) Use a stem to bypass the junction between host bone and graft by 1 cortical diameter.

   2) Gain stability with plates.

   5) Gain stability with screws.

   4) Use a stem to bypass the junction between host bone and graft by 2 cortical diameters.

    

   In type 3 defects (F3 or T3), it is necessary to step cut the allograft and gain stability by using plates and screws or cerclage wires. The stem between host bone and graft must bypass the junction by at least 2 cortical diameters.Correct Answer: Use a stem to bypass the junction between host bone and graft by 1 cortical diameter.

    

   Hip fusion is indicated for all of the following except:

    

   1) Young patients

   3) Patients who are not overweight

   2) Patients with unilateral hip disease

   5) Patients with bilateral hip disease

   4) Young and active patients

    

   Hip fusion is best indicated for the young and active, or heavy patient who does not have bilateral hip disease. Secondary pain occurs in the lumbosacral area in later years, but a good fusion obviates the possible need for multiple revision total hip replacements.Correct Answer: Patients with bilateral hip disease

    

    

   1. (1673) Q1-2068:

      After at least 15 years of follow-up, what percent of patients with hip arthrodesis will have significant back or ipsilateral knee pain:

       

      1) 20%

      3) 60%

      2) 40%

      5) 90%

      4) 80%

       

      At 17 to 50 yearsâ follow-up, approximately 60% of patients with arthrodesis will have significant back or ipsilateral knee pain. Significant back or knee pain at 15 years must be balanced against revision total hip replacement at 15 years.Correct Answer: 60%

       

       

   2. (1674) Q1-2069:

      For a successful hip arthrodesis, the hip should be fused in:

       

      1) 10° flexion, neutral abduction/adduction, 0° of external rotation

      3) 30° flexion, 10° abduction, 10° external rotation

      2) 20° flexion, neutral abduction/adduction, 0° of external rotation

      5) 15° flexion, 10° abduction, 0° external rotation

      4) 15° flexion, 10° abduction, 10° external rotation

       

      A successful hip arthrodesis depends on rigid fixation and proper positioning of the limb at 20° to 30° of flexion relative to the torso, neutral abduction/adduction, and 0° to 5° external rotation.Correct Answer: 20° flexion, neutral abduction/adduction, 0° of external rotation

       

       

   3. (1675) Q1-2070:

   The most important factor in achieving a satisfactory result when converting a fused hip to a total hip arthroplasty is:

    

   1) Placing the limb in proper positioning at time of fusion

   3) Existence of low back pain

   2) Preserving the abductor mechanism at time of fusion

   5) Existence of contralateral hip pain

   4) Existence of ipsilateral knee pain

    

   Preservation of the abductor mechanism is the most important factor when converting an arthrodesis to a total hip arthroplasty.Correct Answer: Preserving the abductor mechanism at time of fusion

    

    

    

   1) Performing the surgery with the knee flexed

   3) Removing a significant portion of the fat pad

   2) Externally rotating the flexed knee and peeling off medial tissues subperiosteally

   5) Keeping the fat pad intact

   4) Cutting the patellofemoral ligament

    

   Performing the surgery with the knee flexed, externally rotating the flexed knee and peeling off medial tissues subperiosteally, removing a significant portion of the fat pad, and cutting the patellofemoral ligament facilitate surgical exposure when performing a total knee replacement.Correct Answer: Keeping the fat pad intact

    

    

   1. (1677) Q1-2072:

      To obtain good patellar tracking during total knee replacement, a surgeon must not:

       

      1) Perform a lateral release

      3) Position the patellar implant slightly medial on the patella

      2) Place the femoral component in slight internal rotation

      5) Check patellar tracking before performing the final cementing of the component

      4) Place the femoral component in slight external rotation

       

      A lateral release is not always required. The femoral component must be slightly externally rotated instead of internally rotated. The patella will track better if the patellar implant is positioned slightly medial.Correct Answer: Place the femoral component in slight internal rotation

       

       

   2. (1678) Q1-2073:

      Bone cuts are more important than soft tissue balancing when performing a total knee replacement. The consideration least important in your decision making is

       

      1) Soft tissue balance

      3) Flexion-extension space balancing

      2) Gender specific knee replacement

      5) Adequate exposure

      4) Bone cuts

       

      Soft tissue balancing and flexion-extension space balancing are as important as the bone cuts.Correct Answer: Gender specific knee replacement

       

       

   3. (1679) Q1-2074:

   In reviewing instability patterns of nonseptic revision total knee replacements, most total knee replacements required revision because of:

    

   1) Malposition of implants

   3) Residual varus, valgus, or flexion contracture

   2) Flexion-extension mismatch

   5) Bony cut malalignment

   4) Soft tissue problems

    

   Most nonseptic revision total knee replacements are a result of soft tissue problems (41%), followed by flexion-extension space mismatch (34%), and insufficient correction of an initial fixed deformity (21%). Only 4% were secondary to bony cut malalignment.Correct Answer: Soft tissue problems

    

    

    

   1) Resecting more femoral bone

   3) Lifting the leg by the ankle in the extended position while pressing proximally on the sole of the foot

   2) Deflating the tourniquet when checking for full extension

   5) The knee will gradually come to full extension with physical therapy after surgery.

   4) Sterilizing a goniometer and checking full extension at the time of surgery

    

   Performing the âbounceâ or âpushâ test is the best test, performed at the time of trial reduction, to predict if a patient will achieve full extension postoperatively. One lifts the leg by the ankle in the extended position while pressing proximally on the sole of the foot.Correct Answer: Lifting the leg by the ankle in the extended position while pressing proximally on the sole of the foot

    

    

   1. (1681) Q1-2076:

      Which of the following patients are least at risk for extensor-mechanism disruption after total knee replacement:

       

      1) Patients with patellar baja

      3) Patients with previous extensor-mechanism realignment

      2) Obese patients

      5) Thin patients

      4) Patients with markedly diminished range of motion

       

      Obese patients, patients with patellar baja, and patients with previous extensor-mechanism realignment, as well as patients with markedly diminished range of motion, are most at risk for extensor-mechanism disruption.Correct Answer: Thin patients

       

       

   2. (1682) Q1-2077:

      Component factors associated with increased stress on the extensor mechanism include all of the following except:

       

      1) An undersized femoral component

      3) Anterior translation of the femoral component

      2) A thick patella

      5) Oversized femoral component

      4) Elevation of the joint line

       

      Increased stress on the extensor mechanism involves an oversized femoral component, anterior translation of the femoral component, a thick patella, and elevation of the joint line. An undersized femoral component does not increase the stress on the extensor mechanism.Correct Answer: An undersized femoral component

       

       

   3. (1683) Q1-2078:

   Which of the following is the most common level of extensor-mechanism disruption after total knee replacement:

    

   1) Quadriceps tendon rupture

   3) Patellar fracture

   2) Patellar tendon disruption

   5) Quadriceps tendon insertion on the patella

   4) Extensor tubercle avulsion

    

   Patellar fracture is the most common level of extensor-mechanism disruption after total knee replacement; however, all of the above have been observed. This is often related to excessive resection of the patella when placing the patella component.Correct Answer: Patellar fracture

    

   Which of the following statements is not true regarding chronic patellar tendon ruptures:

    

   1) Chronic patellar tendon ruptures are usually associated with abnormal tendons.

   3) Chronic patellar tendon ruptures require an allograft substitution.

   2) Chronic patellar tendon ruptures disrupt the extensor mechanism.

   5) The patellar tendon is histologically normal.

   4) Chronic patellar tendon ruptures may occur after total knee replacement.

    

   Chronic patellar tendon ruptures can severely interfere with the extensor mechanism after total knee replacement. They are usually associated with an abnormal tendon and abnormal histology. Often, chronic patellar tendon ruptures must be substituted with an allograft to obtain reasonable function.Correct Answer: The patellar tendon is histologically normal.

    

    

   1. (1684) Q1-2080:

      Which of the following is the best indication for hip arthroscopy:

       

      1. Synovitis

         3) Dysplasia

         2) Osteonecrosis

         5) Rheumatoid arthritis

         4) Labral tears

          

         Indications for hip arthroscopy include labral tears, loose bodies, synovial chondromatosis, chondral flap lesions, and foreign body removal. Hip arthroscopy is less important as a diagnostic tool for a disease entity, such as rheumatoid arthritis or osteonecrosis, because laboratory studies are more specific.Correct Answer: Labral tears

          

          

   2. (1685) Q1-2081:

      Conventional magnetic resonance imaging can detect a labral tear of the hip what percent of the time:

       

      1) 5%

2. 30%

1. 15%

   5) 60%

   4) 45%

    

   Conventional magnetic resonance imaging is only 5% effective in detecting labral tears, but, if combined with gadolinium, its sensitivity is increased to 49%. The dye can more easily identify a labral tear, but it does not approach 100% effectiveness. Clinical symptoms and history are also important when considering hip arthroscopy.Correct Answer: 5%

    

    

   1. (1686) Q1-2082:

   In dysplastic hips, labral tears most often occur in which of the following locations:

    

   1. Posterior

2. Anterior

   1. Lateral

      5) Inferior

      4) Equally distributed

       

      Seventy-two percent of dysplastic hips had labral tears. Sixty-six percent of the tears were anterior, 5% were posterior, and 0.6% were lateral. In dysplastic hips, abnormal pressure is placed on the anterior labrum because of subluxation.Correct Answer: Anterior

       

      In terms of design for posterior stabilized implants, it is important for the components to incorporate         before impingement occurs.

       

      1) No rotation

      3) No flexion

      2) Some hyperextension

      5) 5° of valgus

      4) Some flexion

       

      It is important to incorporate some hyperextension in the posterior stabilized prosthesis because there is a tendency to place the femoral component in flexion and the tibial component in some posterior slope, which creates overall hyperextension.Correct Answer: Some hyperextension

       

       

      1. (1688) Q1-2084:

         When using a primary total knee replacement implant in a patient with distal femoral bone loss:

          

         1) The joint line will be moved proximally.

         3) There will be loss of flexion.

         2) There will be flexion instability.

         5) The joint line remains unchanged.

         4) The joint line will be moved distally.

          

         One moves the joint line proximally with distal femoral bone loss resulting in extension instability and loss of flexion. Tibial bone loss moves the joint line distally. There is no flexion instability in a patient with distal femoral bone loss.Correct Answer: The joint line will be moved proximally.

          

          

      2. (1689) Q1-2085:

         In revision total knee replacement, if one uses a revision femoral component that is thicker than the distal femoral bone loss, then:

          

         1) The joint line will move proximally.

         3) There will be lack of knee flexion.

         2) The joint line will move distally.

         5) There will be increased knee extension.

         4) The joint line remains unchanged.

          

         The joint line is moved distally. The knee does not extend fully and there will be resultant flexion instability.Correct Answer: The joint line will move distally.

          

          

      3. (1690) Q1-2086:

      In a total knee replacement, when sizing the femur from posterior up, if the patient is between sizes and the larger size is implanted, then:

       

      1) Quadriceps excursion will be increased

      3) Quadriceps excursion remains unchanged

      2) Range of motion will be limited

      5) Range of motion remains unchanged

      4) Range of motion increases

       

      Implanting the larger size component will limit both quadriceps excursion and range of motion because it will âstuffâ the joint. The knee will have limited range of motion.Correct Answer: Range of motion will be limited

       

      In a total knee replacement, one of the consequences of sizing from anterior down, when in between sizes is that:

       

      1) It decreases resection of the posterior condyle.

      3) It creates a flexion gap.

      2) It creates an extension gap.

      5) It decreases extension.

      4) It overstuffs the joint.

       

      Sizing from anterior down will increase resection of the posterior condyle. This results in a flexion gap and flexion instability.Correct Answer: It creates a flexion gap.

       

       

      1. (1692) Q1-2088:

         A flexion gap observed when trialing for a total knee replacement can be corrected by:

          

         1) A thinner tibia insert and increased femoral resection

         3) Resecting more tibia

         2) A thicker tibia insert and increased femoral resection

         5) A thicker tibia insert

         4) Resecting more femur

          

         Without going to a posterior stabilized total knee replacement, one can put in a thicker tibia insert and increase the femoral resection to correct a flexion gap. Resecting more tibia increases the flexion gap. Resecting more femur without a thicker tibia insert creates more instability.Correct Answer: A thicker tibia insert and increased femoral resection

          

          

      2. (1693) Q1-2089:

         It is possible to downsize without notching by cutting the distal femur in:

          

         1) 5° varus

         3) 3° flexion

         2) 5° valgus

         5) 3° extension

         4) 10° flexion

          

         The normal trochlear flange of most components diverges approximately 3°. Therefore, if one recuts the distal femur in slight (3°) flexion, then, because the trochlear now diverges 6°, one can use a smaller component.Correct Answer: 3° flexion

          

          

      3. (1694) Q1-2090:

      The consequence of flexing the femoral component of a posterior cruciate-retaining system is:

       

      1. Flexion contracture

         3) Extension contracture

         2) Flexion gap

         5) No consequences

         1. Decreased range of motion

             

            There are no consequences of slightly flexing the femoral component in most cruciate-retaining systems because most prosthetic designs allow for hyperextension of the articulating surfaces. This is not the case with posterior cruciate-substituting systems.Correct Answer: No consequences

             

            Mathematical modeling shows that a round stem versus a rectangular stem in the mid and distal cross-section can increase cement stress up to:

             

            1) 50%

            3) 150%

            2) 100%

         2. 250%

3. 200%

    

   Mathematical modeling of cement stress predicted that a stem with a circular cross-sectional geometry transmits stresses to the cement mantle up to three times greater than stems with a rectangular cross-section.Correct Answer: 250%

    

    

   1. (1696) Q1-2092:

      Place the following strategies for treating deep infection in total hip replacement in order of their effectiveness from 1 to 4, with 1 being the most effective. 1. No antibiotics 2. Systemic antibiotics alone 3. Antibiotic bone cement alone 4. Antibiotic bone cement plus systemic antibiotics

       

      1) 1,2,3,4

      1. 4,2,3,1

         1. 2,4,3,1

4. 4,3,2,1

1. 3,2,4,1

    

   According to Espehaug and colleagues in their assessment of 10,905 primary cemented total knee replacements, the most effective strategy is antibiotic-bone cement plus systemic antibiotics followed by systemic antibiotics alone, antibiotic-bone cement alone, and no antibiotics.Correct Answer: 4,2,3,1

    

    

   1. (1697) Q1-2093:

      Which of the following bone cements is associated with the lowest risk ratio in assessing the risk of deep infection in revision total hip replacement:

       

      1) Simplex (Howmedica, Allendale, NJ) bone cement

      3) Palacos bone cement

      2) Palacos gentamicin bone cement

      5) Vancomycin in bone cement

      4) CMW bone cement

       

      According to Malchau and colleagues, Palacos gentamicin bone cement is associated with the lowest risk ratio for revision total hip replacement. Adding other antibiotics are not as effective as Palacos with gentamicin.Correct Answer: Palacos gentamicin bone cement

       

       

   2. (1698) Q1-2094:

   A midline skin incision is the preferred skin incision in total knee replacement because:

    

   1) A midline skin incision is less disruptive of the arterial network.

   3) A midline skin incision gives better exposure.

   2) A midline skin incision is less disruptive of the sensory nerves.

   5) A midline skin incision is less disruptive of the lymphatic system.

   4) A midline skin incision preserves the extensor mechanism.

    

   The blood supply arises from the terminal branches of the peripatellar anastomotic arterial ring and a midline skin incision is the least disruptive to the arterial network. This results in better wound healing and, therefore, less chance for an infection.Correct Answer: A midline skin incision is less disruptive of the arterial network.

    

   When performing a total knee replacement, posterior stability can be achieved by all of the following except:

    

   1) Soft tissue

   3) Retention of posterior cruciate ligament

   2) The implant

   5) Resection of the anterior cruciate ligament

   4) Resection of the posterior cruciate ligament

    

   Posterior stability can be achieved through the soft tissues or the implant. The posterior cruciate ligament can be retained and posterior instability can still be achieved. The anterior cruciate ligament plays no role in posterior stability and is always resected during a total knee replacement.Correct Answer: Resection of the posterior cruciate ligament

    

    

   1. (1700) Q1-2096:

      Recurrent hemarthrosis of the knee following total knee replacement may be secondary to all of the following except:

       

      1) Entrapment of the synovium between the tibiofemoral articulation

      3) A lax knee

      2) Entrapment of the fat pad between the tibiofemoral articulation

      5) Contracted knee

      4) Entrapment of the synovium between the patellofemoral articulation

       

      Entrapment of synovium or the fat pad between the tibiofemoral and patellofemoral articulation, and a lax knee have been associated with hemarthrosis following total knee replacement and can be treated by synovectomy or by inserting a thicker component.Correct Answer: Contracted knee

       

       

   2. (1701) Q1-2097:

      After total knee replacement, posterolateral knee pain is due to all of the following except:

       

      1) Component overhang

      3) Posterolateral osteophytes

      2) Scarring, more commonly seen in a valgus knee

      5) Popliteus tendonitis

      4) Undersized component

       

      Component overhang, scarring, and posterolateral osteophytes can cause popliteal impingement and a persistent synovitis resulting in popliteus tendinitis and posterolateral pain. An undersized component may present some other problems but not posterolateral knee pain.Correct Answer: Undersized component

       

       

   3. (1702) Q1-2098:

   Pes anserine bursitis that occurs after total knee replacement can be associated with all of the following except:

    

   1) Anteromedial overhang of the component

   3) Inadequate removal of medial osteophytes

   2) Residual varus alignment

   5) Anterolateral overhang of the component

   4) Pes anserine bursitis is an idiopathic occurrence and not related to total knee replacement

    

   Pes anserine bursitis is usually associated with anteromedial component overhang with residual varus alignment or inadequate removal of medial osteophytes.Correct Answer: Anterolateral overhang of the component

    

   All of the following statements are true regarding the Bernese osteotomy except:

    

   1) The Bernese osteotomy was popularized by Ganz.

   3) The Bernese osteotomy allows for unrestricted correction while keeping the pelvic ring intact.

   2) The Bernese osteotomy is a reorientation osteotomy.

   5) The Bernese osteotomy can be used only in anteverted dysplastic hips.

   4) The Bernese osteotomy can be used in approximately 15% of dysplastic hips.

    

   The Bernese periacetabular osteotomy, which was popularized by Ganz, is a reorientation osteotomy that allows for unrestrained correction while keeping the pelvic ring intact and can be used in approximately 17% of dysplastic hips. The Bernese osteotomy can be used in anteverted and retroverted dysplastic hips.Correct Answer: The Bernese osteotomy can be used only in anteverted dysplastic hips.

    

    

   1. (1704) Q1-2100:

      The two most commonly used scoring techniques to assess and report the results of knee arthroplasty are the Hospital for Special Surgery knee score and the Knee Society score. Although they are the most commonly used scoring techniques, their main weakness is:

       

      1) Examiner and intraobserver bias

      3) Based on questionairre completed by the patient

      2) Can only be used in patients with osteoarthritic knees

      5) Has no intervention of a health care provider

      4) Derived from patient outcomes

       

      The Hospital for Special Surgery knee score and the Knee Society score have examiner and intraobserver bias. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score is based on a questionnaire completed by the patient and is derived from patient outcomes without intervention of a healthcare provider.Correct Answer: Examiner and intraobserver bias

       

       

   2. (1705) Q1-2101:

      Which of the following scoring techniques is the weakest when used to compare specific physical dynamics of a prosthesis:

       

      1. Hospital for Special Surgery knee score

         3) Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score

         2) Knee Society score

         5) Mayo Clinic knee score

         4) Iowa knee score

          

         The Hospital for Special Surgery knee score and the Knee Society score provide more detailed information about the physical dynamics of a prosthesis than the WOMAC score. A combination of the three scores correlate well in their measurement of total knee replacement outcomes.Correct Answer: Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score

          

          

   3. (1706) Q1-2102:

   What percentage of nonsteroidal anti-inflammatory drug (NSAID) users annually develop a serious gastrointestinal (GI) complication:

    

   1) 2%

   1. 10%

      1. 4%

2. 20%

1. 15%

    

   Annually, 1% to 2% of NSAID users develop a serious GI complication. The risk of bleeding, perforation, hospitalization, or death is three times higher among NSAID users than non-NSAID users.Correct Answer: 2%

    

   Nonsteroidal anti-inflammatory drugs (NSAIDs) work by:

    

   1) Inhibiting the conversion of arachidonic acid to prostaglandin

   3) Increasing the level of prostaglandin in the joint

   2) Increasing prostaglandin synthesis

   5) Decreasing glycosaminoglycan synthesis

   4) Increasing glycosaminoglycan synthesis

    

   Prostaglandins are the key components of the inflammatory process and work by inhibiting the conversion of arachidonic acid to prostaglandin.Correct Answer: Inhibiting the conversion of arachidonic acid to prostaglandin

    

    

   1. (1708) Q1-2104:

      Cyclooxygenase (Cox-1) is found:

       

      1) Only in the gastrointestinal tract

      3) Only in the platelets

      2) Only in the kidneys

      5) Widely expressed throughout the body

      4) Only in the articular cartilage

       

      Cox-1 is the ubiquitous form of the cyclooxygenase enzyme that is widely expressed throughout the body. Cox-1 is not found in only one specific organ.Correct Answer: Widely expressed throughout the body

       

       

   2. (1709) Q1-2105:

      Steroid injections work in osteoarthritic joints by the following mechanism:

       

      1. Increasing phagocytes

         3) Increasing synthesis of inflammatory mediators

         2) Inhibiting lysosomal enzyme release

         5) Stabilizing synthesis of inflammatory mediators

         4) Stabilizing phagocytes

          

         Steroids work by inhibiting lysosomal enzyme release, decreasing phagocytes, and decreasing the synthesis of inflammatory mediators.Correct Answer: Inhibiting lysosomal enzyme release

          

          

   3. (1710) Q1-2106:

      Intra-articular steroids decrease the synthesis of prostaglandin and interleukin-1 by:

       

      1) 90%

      1. 30%

         1. 20%

2. 70%

1. 50%

    

   Intra-articular steroids decrease the synthesis of prostaglandin and interleukin-1 by as much as 50%.Correct Answer: 50%

    

    

   1. (1711) Q1-2107:

   Intra-articular steroids change synovial fluid characteristincs by:

    

   1) Stabilizing phagocytes

   3) Increasing the hyaluronic acid concentration in a joint

   2) Stabilizing synthesis of inflammatory mediators

   5) Intra-articular steroids do not change synovial fluid characteristics

   4) Decreasing the hyaluronic acid concentration in a joint

    

   Intra-articular steroids change synovial fluid characteristics by increasing hyaluronic acid concentration.Correct Answer: Increasing the hyaluronic acid concentration in a joint

    

   To reduce the chance of irritation when injecting a knee with hyaluronic acid, which of the following approaches is recommended:

    

   1) A medial approach in a partially bent knee

   3) A direct lateral injection

   2) A direct straight injection

   5) A direct injection through the patellar tendon

   4) A medial approach in an extended knee

    

   The chance of an injection site irritation is 5.2% with a medial approach in a partially bent knee, 2.4% with a straight injection, and 1.5% with a direct lateral approach. There is also an increased chance of irritation with a direct patellar tendon injection.Correct Answer: A direct lateral injection

    

    

   1. (1713) Q1-2109:

      Indications for high tibial osteotomy include all of the following except:

       

      1) 10° to 15° of varus deformity on weight-bearing radiographs

      3) Flexion contracture less than 15°

      2) 90° preoperative range of motion

      5) Age younger than 60 years

      4) 60° preoperative range of motion

       

      Indications for a high tibial osteotomy include age younger than 60 years, 10° to 15° varus deformity, 90° preoperative arc range of motion, and flexion contracture less than 15°.Correct Answer: 60° preoperative range of motion

       

       

   2. (1714) Q1-2110:

      Contraindications to high tibial osteotomy include:

       

      1) Lateral compartment narrowing

      3) Medial compartment bone loss of more than 3 mm

      2) Lateral tibial subluxation more than 1 cm

      5) All of the above

      4) Ligament instability

       

      Lateral compartment narrowing, lateral tibial subluxation of more than 1 cm, medial compartment bone loss of more than 3 mm, and ligament instability are contraindications to high tibial osteotomy.Correct Answer: All of the above

       

       

   3. (1715) Q1-2111:

   The incidence of lateral gonarthrosis in women is:

    

   1) Lower than men

   3) Two times higher in women

   2) Same as men

   5) Five times higher in women

   4) Three times higher in women

    

   The incidence of primary lateral gonarthrosis in women is five times higher than in men, and the average age of patients is 55 to 60 years. The body habitus of women tend to align more weight on the lateral compartment when compared to men.Correct Answer: Five times higher in women

    

   The majority of patients with lateral compartment arthritis have:

    

   1) Rheumatoid arthritis

   3) Collagen vascular disease

   2) Neurologic condition (e.g., Polio)

   5) Trauma

   4) Osteoarthritis

    

   Rheumatoid arthritis usually involves the lateral compartment because it is a bicompartmental disease. Although most patients with osteoarthritis have medial compartment arthritis, they still have a significant higher incidence of lateral arthritis than any other disease. The incidence of lateral compartment arthritis is lower in trauma, collagen vascular disease, or patients with neurologic conditions like polio.Correct Answer: Osteoarthritis

    

    

   1. (1717) Q1-2113:

      Which of the following is not a good indication for a varus-producing supracondylar femoral osteotomy (SFO):

       

      1) Valgus deformity less than 15°

      3) 90° arc of range of motion

      2) Valgus joint-line tilt more than 10°

      5) Young patients

      4) Old patients

       

      Varus producing supracondylar femoral osteotomy is indicated for a valgus deformity less than 15°, valgus joint line tilt more than 10° in a patient with at least a 90° arc of motion. The procedure is also best indicated in stout, young patients who are involved in heavy labor jobs.Correct Answer: Old patients

       

       

   2. (1718) Q1-2114:

      When performing a supracondylar femoral osteotomy, it is recommended to correct the tibiofemoral angle:

       

      1) 2°

      3) 4° to 6°

      2) 2° to 4°

      5) More than 8°

      4) 6° to 8°

       

      Correcting the tibiofemoral angle between 4° to 6° transfers 80% of the weight to the medial angle.Correct Answer: 4° to 6°

       

       

   3. (1719) Q1-2115:

   The most common problem encountered with total knee arthroplasty (TKA) after high tibial osteotomy is:

    

   1) Offset of tibial plateau from tibial shaft

   3) Dealing with skin incision

   2) Patella infera

   5) High riding patella

   1. Tracking of patella

       

      Patella infera is encountered 80% of the time after a high tibial osteotomy. Patella infera makes it difficult for a surgeon to visualize and dislocate the patella laterally, and it also makes for a difficult salvage for a total knee replacement.Correct Answer: Patella infera

       

      When careful evaluation after primary total knee arthroplasty (TKA) is performed, the results of TKA after previous high tibial osteotomy (HTO) have a Knee Society good-to-excellent score what percentage of the time:

       

      1) 20%

      3) 60%

      2) 40%

   2. 90%

   4) 80%

    

   Primary TKA with respect to Knee Society scores and operative complications shows that a primary TKA group scored 88% good to excellent results compared to 63% for the post-HTO group.Correct Answer: 60%

    

    

   1. (1721) Q1-2117:

      Subchondral drilling for cartilage defects is effective for:

       

      1. Varus alignment

         3) Subchondral sclerosis

         2) Valgus alignment

         5) Rheumatoid arthritis

         4) Fibrocartilage formation

          

         Subchondral drilling allows the blood supply to form clot-containing stem cells from which fibrocartilage forms. It is not indicated in patients with systemic disease like rheumatoid arthritis. It is ineffective for varus or valgus alignment or subchondral sclerosis.Correct Answer: Fibrocartilage formation

          

          

   2. (1722) Q1-2118:

      When performing a mosaicplasty for cartilage defects, the defects must be:

       

      1. Less than 1 cm

         3) Less than 2 cm

         2) Less than 1.5 cm

         5) Less than 3 cm

         4) Less than 2.5 cm

          

         When performing a mosaicplasty for cartilage defects, the best results are obtained with defects less than 2 cm. The plugs should measure 2.5 mm in length. Mosaicplasty results for defects larger than 2 cm have not been as gratifying.Correct Answer: Less than 2 cm

          

          

   3. (1723) Q1-2119:

   Mobile-bearing total knee replacement (TKR) implants are designed to have how many articulations:

    

   1) 0

   1. 2

      1. 1

2. 4

1. 3

    

   Mobile-bearing TKR implants are designed to have two articulations, one between the femoral and tibial component and the other between the tibial component and base plate on the tibia.Correct Answer: 2

    

   After 5 years, cemented all-polyethylene components in total knee replacement have a loosening rate of:

    

   1) 10%

   1. 30%

      1. 20%

2. 50%

1. 40%

    

   At 5 years, cemented all-polyethylene tibial components in total knee replacement have a loosening rate of 20%. A loosening rate of 20% is unacceptable, therefore, cemented all-polyethylene tibial components are no longer used in total knee replacements.

   New all poly tibial components are presently being investigated, but not for general use presently.Correct Answer: 20%

    

    

   1. (1725) Q1-2121:

      When performing a total knee replacement (TKR) on a patient with previous skin incisions on the knee, if a different skin incision is to be made it is recommended that the distance between the incisions should be:

       

      1) 2 cm

      3) 4 cm

      2) 3 cm

      5) 7 cm

      4) 5 cm

       

      Most authors recommend a 7-cm distance between skin incisions. If the distance between the incisions is less than 7 cm, then the chance of skin slough increases.Correct Answer: 7 cm

       

       

   2. (1726) Q1-2122:

      The medial parapatellar skin incision for total knee replacement (TKR):

       

      1) Limits lateral side exposure and interferes with the blood supply of the lateral skin flap

      3) Makes the lateral skin flap smaller

      2) Necessitates a lateral release

      5) Provides excellent exposure for a TKR

      4) Increases the blood supply to the patella

       

      The medial parapatellar skin incision limits exposure of the lateral compartment and interferes with the blood supply of the lateral skin flap.Correct Answer: Limits lateral side exposure and interferes with the blood supply of the lateral skin flap

       

       

   3. (1727) Q1-2123:

   Which of the following is not true regarding a subvastus arthrotomy for total knee replacement (TKR):

    

   1) A lift of the entire quadriceps mechanism

   3) A danger of causing injury to the femoral artery

   2) A poor exposure of the lateral aspect of the knee joint

   5) Provides good visualization in an obese patient

   4) Provides fair exposure in a thin patient

    

   All of the answers are associated with the subvastus arthrotomy. A subvastus arthrotomy is a particularly difficult approach in obtaining visualization in an obese patient.Correct Answer: Provides good visualization in an obese patient

    

   Which of the following is a true statement concerning the quadriceps snip technique:

    

   1) The quadriceps snip technique involves lengthening the tendon in a

   3) The quadriceps snip technique significantly weakens the extensor tendon.

   2) The quadriceps snip technique enters the quadriceps tendon with a

   5) The quadriceps snip technique involves a horizontal cut in the extensor tendon.

   4) The quadriceps snip technique permits extended exposure.

    

   The quadriceps snip technique entails dividing the tendon proximally in an oblique fashion to permit extended exposure.Correct Answer: The quadriceps snip technique permits extended exposure.

    

    

   1. (1729) Q1-2125:

      Which of the following is a true statement regarding intramedullary instrumentation when performing bone cuts in total knee replacement (TKR):

       

      1) Intramedullary instrumentation is equally as accurate as extramedullary devices in all knees.

      3) Intramedullary instrumentation is less accurate than extramedullary devices in valgus knees.

      2) Intramedullary instrumentation is less accurate than extramedullary devices in varus knees.

      5) Intramedullary instrumentation is more accurate than extramedullary devices in valgus knees.

      4) Intramedullary instrumentation is more accurate than extramedullary devices in varus knees.

       

      Valgus in the tibia shaft may be up to 70%, and intramedullary rods cannot be fully placed into the tibia. Extramedullary techniques are recommended.Correct Answer: Intramedullary instrumentation is less accurate than extramedullary devices in valgus knees.

       

       

   2. (1730) Q1-2126:

      When total knee replacement surgery is complete, the alignment of the knee must be:

       

      1) Neutral

      3) 5° of valgus in the femur

      2) 2° of valgus in the tibia

      5) 7° of valgus in the femur

      4) 7° of valgus in the tibia

       

      The tibial cut is perpendicular to the tibial axis, the femoral cut is made in 4° to 6° valgus, and the knee aligned in 4° to 6° of valgus provided the ligaments are balanced.Correct Answer: 5° of valgus in the femur

       

       

   3. (1731) Q1-2127:

   Overall objectives in total knee replacement (TKR) should include all of the following except:

    

   1) Valgus aligned knee

   3) Midline tracking patella

   2) Range of motion 0° to 125°

   5) Neutral aligned knee

   4) Collateral ligament balance at full extension and 90°

    

   To have a satisfactory alignment one should have a valgus aligned knee, not a neutral aligned knee. Range of motion should be 0° to 125° with midline tracking patella. The collateral ligament should be balanced at full extension an 90°.Correct Answer: Neutral aligned knee

    

   What is the measured resection technique when performing a total knee replacement:

    

   1) Removes 20% more bone than cut

   3) Entails ligament balancing in extension

   2) Removes an exact amount of bone to fit in the prosthetic device

   5) Incorporates ligament balancing in flexion and extension

   4) Entails ligament balancing in flexion

    

   The measured resection technique is a philosophy that removes the exact amount of bone necessary to fit in the prosthetic device for the femur and tibia, and does not detail ligament balancing. The flexion-extension gap technique incorporates ligament balancing with the bony cuts that give equal flexion and extension gaps.Correct Answer: Removes an exact amount of bone to fit in the prosthetic device

    

    

   1. (1733) Q1-2129:

      When performing a total knee replacement, if you discover that the gap in flexion is larger than the gap in full extension, you should:

       

      1) Remove more bone from the tibia

      3) Remove more bone from the femur in extension

      2) Remove more bone from the femur in flexion

      5) Put in a posterior stabilized prosthesis

      4) Remove more bone from the posterior femur

       

      By removing more bone from the femur in extension and using a higher polyethylene component, the flexion and extension gaps can be equalized. If this does not correct the problem, then one should proceed to a posterior stabilized prosthesis.Correct Answer: Remove more bone from the femur in extension

       

       

   2. (1734) Q1-2130:

      When performing a total knee replacement, if you discover that the gap in flexion is smaller than the gap in extension:

       

      1) More bone should be removed from the femur in extension

      3) More bone should be removed from the posterior femur

      2) A larger polyehtylene component should be used

      5) A smaller polyethylene component should be used

      4) The femoral component should be upsized

       

      If the flexion gap is smaller than the extension gap, the knee should be balanced by removing more posterior bone from the femur or downsizing the femoral component.Correct Answer: More bone should be removed from the posterior femur

       

       

   3. (1735) Q1-2131:

   Which of the following can lead to patellar dislocation in total knee replacement:

    

   1) Internal rotation of femoral component

   3) Too large a femoral component

   2) External rotation of femoral component

   5) Too large a tibial component

   4) External rotation of tibial component

    

   Internal rotation of either the femoral or tibial component may lead to patellar dislocation. External rotation of the femoral or tibial component does not usually lead to dislocation, and increased size of the femoral or tibial component will not predispose to patella dislocation.Correct Answer: Internal rotation of femoral component

    

   Epidural analgesia in the postoperative period after total joint replacement is widely used and is associated with all of the following complications except:

    

   1) Nausea

   3) Peroneal nerve palsy

   2) Respiratory depression

   5) Hypotension

   4) Femoral nerve palsy

    

   Nausea, hypotension, respiratory depression, and peroneal nerve palsy are associated with epidural analgesia. Be aware of an epidural bleed secondary to anticoagulation efforts for deep venous thrombosis prophylaxis.Correct Answer: Femoral nerve palsy

    

    

   1. (1737) Q1-2133:

      Painful "clunking" sensations upon active extension from 60° to 30° in patients with total knee replacements are:

       

      1) Fibrous nodules under patellar tendon

      3) Fibrous nodule under distal quadriceps tendon

      2) Seen only in posterior-stabilized total knee replacement because of fibrous build up in the nodule

      5) Oversized tibial components

      4) Seen only in posterior cruciate retaining total knee replacements

       

      This painful clunking sensation from 60° to 30° is caused by a fibrous nodule under the distal quadriceps tendon. Contributing factors include a large patellar component with proximal overhang and an abrupt change in the radius of curvature of the femoral component that irritates the quadriceps tendon.Correct Answer: Fibrous nodule under distal quadriceps tendon

       

       

   2. (1738) Q1-2134:

      All of the following are reported advantages of metal-backed patella components except:

       

      1) Metal-backed patella components minimize deformity of overlying polyethylene.

      3) Metal-backed patella components allow for cementless fixation.

      2) Metal-backed patella components permit more evenly distribution of load transmissions.

      5) Metal-backed patella components reduce the polyethylene thickness at the periphery of the implant.

      4) Metal-backed patella components increase deformity of the overlying polyethylene.

       

      Metal-backed patella components minimize deformity of the overlying polyethylene and do not increase deformity. These components enable an even distribution of load transmissions and reduce the polyethylene thickness at the periphery of the implant. Metal-backed patella components also allow for cementless fixation of the patellae component.Correct Answer: Metal-backed patella components increase deformity of the overlying polyethylene.

       

       

   3. (1739) Q1-2135:

   Failure modes of metal-backed patella designs include all of the following except:

    

   1) Dissociation of polyethylene and metal plate

   3) Femoral component exposed to the metal of the patella component

   2) Component fractures

   5) Metallic synovitis

   1. Increased risk of patella dislocation

       

      The polyethylene wear exposing the metal to wear against the femoral component is the ultimate result of all of the above failure modes except increased patella dislocation.Correct Answer: Increased risk of patella dislocation

       

      The incidence of patella component loosening is:

       

      1) 4%

      3) 2%

      2) 10%

   2. 15%

   4) 8%

    

   The incidence of patella component loosening is less than 2%. Factors predisposing to loosening include cementation into deficient bone, component malposition, patellar subluxation or fracture, patellar avascular necrosis, asymmetric patellar bone resection, and loosening of other components. Treatment options include observation, component revision, patellectomy or component removal, and patellar arthroplasty if bone stock is sufficient.Correct Answer: 2%

    

    

   1. (1741) Q1-2137:

      The preferred means for fixation of patellar components is:

       

      1) Large, central patellar lugs

      3) Three large patellar-fixation lugs

      2) Two parallel patellar lugs

      5) One central and two peripheral-fixation lugs

      4) Three small peripheral-fixation lugs

       

      Large, central patellar-fixation lugs remove a significant amount of bone, which contributes to patellar fractures. Three small peripheral-fixation lugs are preferred in most designs.Correct Answer: Three small peripheral-fixation lugs

       

       

   2. (1742) Q1-2138:

      The majority of patellofemoral instability cases are secondary to:

       

      1) Trauma

      3) Surgical technique

      2) Failure to perform a lateral release

      5) Patient related

      4) Prosthetic design

       

      Trauma, failure to perform a lateral release, and prosthetic design are associated with patellofemoral instability, but the majority of patellofemoral instability cases are secondary to errors in surgical judgement and technique.Correct Answer: Surgical technique

       

       

   3. (1743) Q1-2139:

   Which of the following conditions related to the femur does not influence patellofemoral mechanics and stability:

    

   1) Selecting an oversized femoral component

   3) Medial positioning of the femoral component

   2) Improper femoral component rotation

   5) Excessive flexion gap

   4) Excessive axial valgus alignment

    

   The femoral component size, rotation, position, and alignment influence patellofemoral mechanics. For instance, an oversized femoral component leads to "overstuffing" that results in decreased flexion of the knee. Excessive flexion gap does not influence patellofemoral mechanics.Correct Answer: Excessive flexion gap

    

   The position of the tibial component influences patellar biomechanics. The best position to place the component is:

    

   1) Internal rotation of the tibial component

   3) Medialization of tibial component

   2) External rotation of the tibial component

   5) External rotation and lateralization

   4) Lateralization of tibial component

    

   The tibial component must be positioned in external rotation and lateralized when possible. Internal rotation or medialization predispose to patellar subluxation.Correct Answer: External rotation and lateralization

    

    

   1. (1745) Q1-2141:

      Which of the following is not a risk factor for fracture of the distal femur proximal to total knee replacement (TKR):

       

      1) Rheumatoid arthritis and osteopenia

      3) Osteoarthritis

      2) Anterior femoral notching

      5) Revision arthroplasty

      4) Steroid use

       

      The risk factors associated with fracture of the distal femur proximal to TKR are anterior femoral notching (especially if more than 3 mm in depth), rheumatoid arthritis, steroid use, osteopenia, revision arthroplasty, neuromuscular disorders, stiff knee, or poor flexion of the TKR.Correct Answer: Osteoarthritis

       

       

   2. (1746) Q1-2142:

      Risk factors for peroneal nerve palsy after total knee replacement (TKR) include all of the following except:

       

      1) Severe valgus deformity

      3) Epidural anethesia

      2) Flexion contracture

      5) Increased flexion gap

      4) Previous lumbar laminectomy and valgus osteotomy

       

      Severe valgus deformity, flexion contracture, and epidural anesthesia are risk factors associated with peroneal nerve palsy following TKR. Previous lumbar laminectomy and previous valgus osteotomy of the tibia also increase a patientâs chance of peroneal nerve palsy.Correct Answer: Increased flexion gap

       

       

   3. (1747) Q1-2144:

      The most common cause of stiffness after total knee replacement (TKR) is:

       

      1. Implant selection

         3) Flexion contracture of the contralateral extremity

         2) Poor preoperative range of motion

         5) Tight posterior cruciate ligament (PCL) after implanting a PCL-retaining knee

         4) A large spacer

          

         Poor preoperative range of motion is the main cause of stiffness after TKR.Correct Answer: Poor preoperative range of motion

          

          

   4. (1748) Q1-2145:

   The femoral component can be malaligned in how many different directions:

    

   1) 1

   1. 4

      1. 2

2. 8

1. 6

    

   The femoral component can be malaligned in one of eight different directions.Correct Answer: 8

    

    

    

   1) 6 mm

   3) 10 mm

   2) 8 mm

   5) 15 mm

   4) 12 mm

    

   Inserts thinner than 6 mm are associated with easy failure and osteolysis, caused by fracture and wear of the polyethylene.Correct Answer: 6 mm

    

    

   1. (1750) Q1-2147:

      Which of the following tests helps in the diagnosis of reflex sympathetic dystrophy:

       

      1) Magnetic resonance imaging

      3) Bone scanning

      2) Computerized tomography scanning

      5) Tomography

      4) Ultrasonography

       

      Usually, reflex sympathetic dystrophy is a diagnosis of exclusion characterized by a syndrome of pain out of proportion to the clinical findings; a bone scan may demonstrate increased uptake in the affected area.Correct Answer: Bone scanning

       

       

   2. (1751) Q1-2148:

      Erythema, warmth, stiffness, and cutaneous hypersensitivity after total knee replacement associated with pain is usually caused by:

       

      1) Infection

      3) Gout

      2) Reflex sympathetic dystrophy

      5) Vascular insufficiency

      4) Patellar malalignment

       

      These symptoms, in addition to pain out of proportion to clinical findings, characterize a slow postoperative course. Poor function after total knee replacement is usually secondary to reflex sympathetic dystrophy.Correct Answer: Reflex sympathetic dystrophy

       

       

   3. (1752) Q1-2149:

   Aspirating synovial fluid prior to total knee replacement revision surgery after ensuring that a patient is not concurrently on antibiotic therapy has a sensitivity, specificity, and accuracy of:

    

   1) 20% to 40%

   3) Less than 20%

   2) 60% to 80%

   5) 90% to 100%

   4) 40% to 60%

    

   Providing the patient is off antibiotics, the sensitivity, specificity, and accuracy of snynovial fluid aspiration is 100%. Antibiotic administration before or during the aspiration will mask the analysis.Correct Answer: 90% to 100%

    

   occurs:

    

   1) During the induction of anesthesia

   3) 12 hours postoperative

   2) During the preparation of the femoral canal

   5) 7 days postoperative

   4) 24 hours postoperative

    

   The process of thrombosis starts during the preparation of the femoral canal. Elevation in thrombogenic factors is most pronounced during preparation of the femoral canal, especially with insertion of a cemented femoral component. Mechanical manipulation of the limb (dislocation of the femoral head) may also cause intimal damage or occlusion of the femoral vein.Correct Answer: During the preparation of the femoral canal

    

    

   1. (1789) Q1-2188:

      Place the following in the correct order of increasing modulus of elasticity (least to greatest):

       

      1) Cobalt-chrome, titanium, compact bone, stainless steel

      3) Compact bone, titanium, cobalt-chrome, stainless steel

      2) Titanium, compact bone, cobalt-chrome, stainless steel

      5) Titanium, compact bone, stainless steel, cobalt-chrome

      4) Compact bone, titanium, stainless steel, cobalt-chrome Modulus of elasticities are as follows in Gpa (psi 3 106 ):

      Compact bone: 21 (3)

      Titanium: 96 (14)

      Stainless steel: 193 (28)

      Cobalt-chrome: 235 (34)

      Correct Answer: Compact bone, titanium, stainless steel, cobalt-chrome

       

       

   2. (1790) Q1-2189:

      Which of the following precautionary measures should be taken to prevent a periprosthetic fracture when removing components from a patient with a previous compression hip screw:

       

      1) Cemented femoral component with cement augmentation of the screw holes and full weight bearing

      3) Toe touch weight bearing for 6 weeks

      2) Plate augmentation with circlage wires and protected weight bearing

      5) Bypass the last screw hole with a cemented femoral component by two cortical diameters and protected weight bearing

      4) Cortical strut allograft and protected weight bearing

       

      Stress risers are generated when a screw is removed from the femur, weakening the bone for at least 4 weeks. Larger defects (50%) of the cortical width can reduce torsional strength up to 44%. Bypassing the defect by two cortical diameters with a cemented stem doubles the boneâs strength.Correct Answer: Bypass the last screw hole with a cemented femoral component by two cortical diameters and protected weight bearing

       

       

   3. (1791) Q1-2190:

      Which of the following radiographic changes is apparent after placement of a fully porous-coated, cobalt-chrome femoral stem:

       

      1) Proximal-femoral osteopenia

      3) Radiolucency around the acetabular cup

      2) Distal-femoral osteopenia

      5) Osteopenia adjacent to the entire femoral component

      4) Increased mineralization proximally

       

      The most severe stress shielding occurs with an extensively porous-coated chrome-cobalt stem. Stress shielding occurs as the load is transferred from the hip joint to the proximal femur. The load that was previously carried by the hip joint is now shared with the implant. This change leads to remodeling of the proximal femur, resulting in a decreased density and thinning of the proximal portion of the femur. In a group of patients characterized as having severe stress-shielding based on plain radiographs, no adverse effects were noted in terms of hip scores, presence of osteolysis, or need for revision.Correct Answer: Proximal-femoral osteopenia

       

   4. (1792) Q1-2191:

      Noncircumferential-porous coating leads to which of the following adverse effects:

       

      1) Increased rates of infection

      3) Increased rates of distal osteolysis and late femoral loosening

      2) Increased rates of stress shielding

      5) Increase rates of thigh pain

      4) Increase rates of thigh pain

       

      Noncircumferential-porous coating allows a pathway for particulate debris (polywear) to the distal part of the stem, promoting osteolysis. The polyethylene wear debris migrates through the pathway promoting osteolysis and, ultimately, failure.Correct Answer: Increased rates of distal osteolysis and late femoral loosening

       

       

   5. (1793) Q1-2192:

      The best position for hip arthrodesis is:

       

      1) Neutral abduction/adduction, 20° to 30° flexion, and neutral internal/external rotation

      3) Neutral abduction/adduction, full extension, and neutral internal/external rotation

      2) Neutral abduction/adduction, full extension, and neutral internal/external rotation

      5) 10° abduction, 20° to 30° flexion, neutral internal/external rotation

      4) Neutral abduction/adduction, 15º to 20° flexion, and neutral internal/external rotation

       

      The favored position of hip arthrodesis is 20° to 30° flexion, neutral (or minimal adduction) adduction/abduction, and neutral internal/external rotation (can be slight external rotation). Insufficient flexion makes sitting difficult, while too much flexion makes standing difficult due to increased lumbar lordosis. Abduction and internal rotation should be avoided.Correct Answer: Neutral abduction/adduction, 20° to 30° flexion, and neutral internal/external rotation

       

       

   6. (1794) Q1-2193:

      Which of the following total hip arthroplasty (THA) positions increases the chances of an anterior dislocation:

       

      1) Flexion, adduction, and internal rotation

      3) Extension, adduction, and external rotation

      2) Flexion, abduction, and internal rotation

      5) Extension, abduction, and internal rotation

      4) Extension, adduction, and internal rotation

       

      The most common direction for THA dislocation is posterior. Dislocation may be associated with a posterior approach, poor technique, or previous surgery. Posterior dislocations are accentuated by placing the hip in flexion, adduction, and internal rotation (i.e., rising from a low-seated chair). Less common anterior dislocations occur after an anterior approach or with anteversion of the cup or femoral component (or both). The position for dislocation is accentuated by extension, adduction, and external rotation.Correct Answer: Extension, adduction, and external rotation

       

       

   7. (1795) Q1-2194:

   Loosening of a cemented metal-backed polyethylene acetabular component occurs at which of the following junctions:

    

   1) The cement-bone interface

   3) The metal-polyethylene interface as a result of micromotion

   2) The cement-metal interface

   5) Both the cement-bone and cement-metal interface

   4) Result of fracture and dissolution through the structure of the cement

    

   Autopsy studies show that the loosening of cemented components occurs at the cement-bone interface. Loosening occurs first at the periphery and proceeds toward the dome. The bone resorption at the cement-bone interface is a response to polyethylene debris.Correct Answer: The cement-bone interface

    

    

    

   1) External iliac vein

   3) Bladder

   2) Internal iliac artery

   5) Common iliac artery

   4) Obturator vein

    

   Placing screws in the acetabular cup in the anterior-superior or anterior-inferior quadrant is not advised due to the proximity of the external iliac vein and the obturator artery, respectively.Correct Answer: External iliac vein

    

    

   1. (1797) Q1-2196:

      During revision surgery for total hip arthroplasty, the accepted standard for the presence of an infection on frozen tissue histological analysis is:

       

      1) Five mononuclear cells per high-powered field

      3) Five polymorphonuclear cells per high-powered field

      2) Ten mononuclear cells per high-powered field

      5) One polymorphonuclear cell per high-powered field

      4) Ten polymorphonuclear cells per high-powered field

       

      Frozen section analysis is important in revision surgery to determine why a component has become loose. Ten polymorphonuclear cells per high-powered field lower the sensitivity for infection but do not reduce the specificity to diagnose an infection. Five polymorphonuclear cells per high-powered field are the current standard accepted as diagnostic for an infection. Mononuclear cells can be present in the face of aseptic loosening or polywear disease. Polymorphonuclear cells are diagnostic of biologic infectious response.Correct Answer: Five polymorphonuclear cells per high-powered field

       

       

   2. (1798) Q1-2197:

      Which of the following is not an indication for an intertrochanteric osteotomy:

       

      1. Malunion of a fracture in the trochanter region

         3) Avascular necrosis involving more than 50% of the femoral head

         2) Shortening, lengthening, or derotation osteotomies to realign the extremity

         5) Avascular necrosis involving less than 25% of the femoral head

         4) Avascular necrosis involving less than 50% of the femoral head

          

         Malunion fractures in the trochanter region and shortening, lengthening, or derotation osteotomies to realign the extremity are indications for an intertrochanteric osteotomy. Avascular necrosis involving more than 50% of the femoral head is a contraindication for intertrochanteric osteotomy.Correct Answer: Avascular necrosis involving more than 50% of the femoral head

          

          

   3. (1799) Q1-2198:

   Normal activities, such as walking 1 km/hour, create forces across the hip joint of       times body weight:

    

   1) 1

   1. 3

      1. 2

2. 5

1. 4

 

Normal activities increase forces over the hip to three times body weight. Jogging increases forces across the hip by five to eight times body weight.Correct Answer: 3

 

 

 

1. Improving congruency by restoring proper biomechanics

3) Timely intervention with minimal arthrosis

2) Reorienting the weight bearing surfaces to transfer load in compression rather than shear

5) Bone-to-bone aposition

4) Advanced osteoarthritis

 

Principles of osteotomy include improving congruency by restoring proper mechanics, reorienting the weight bearing surfaces to transfer load in compression rather than shear, bone-to-bone aposition, and timely intervention with minimal arthrosis.Correct Answer: Advanced osteoarthritis

 

 

1. (1801) Q1-2200:

   The technical goals of osteotomy should include all of the following except:

    

   1) Eliminating impingement

   3) Sacrificing motion

   2) Correcting deformity

   5) Altering range of motion

   4) Restoring pain-free functional range of motion

    

   Technical goals of osteotomy include eliminating impingement, correcting deformity, and restoring a pain-free functional range of motion. Motion should not be gained or lost, but the range can be altered.Correct Answer: Sacrificing motion

    

    

2. (1802) Q1-2202:

   The best index to measure acetabular deficiency in the coronal plane is:

    

   1) Tear drop ratio

   3) Hilgenreiner angle

   2) Center edge angle of Wiberg

   5) Greater trochanter-pubic ratio

   4) Leg length measurements

    

   Literature from Europe and North America suggests that a patient with acetabular dysplasia whose anteroposterior radiograph shows a center edge angle of Wiberg less than 15° is a good candidate for periacetabular osteotomy.Correct Answer: Center edge angle of Wiberg

    

    

3. (1803) Q1-2203:

In cemented total hip arthroplasty, the initial event in the loosening process of the femoral component occurs at the:

 

1) Bone-cement interface

3) Thin cement mantle with fatigue fractures of cement

2) Prosthesis-cement interface

5) Large cement mantles

4) Simultaneously at the bone cement and prosthesis cement interface

 

From the long-term observations of radiograph changes occurring around well-performed cemented total hip arthroplasties, fatigue fracture of cement, especially in areas of thin cement mantles, leads to loss of stability of the femoral component within the cement mantle.Correct Answer: Thin cement mantle with fatigue fractures of cement

 

 

 

1) Bone-cement interface

3) Within the cement

2) Prosthesis-cement interface

5) Within the bone

4) Simultaneously at all three locations

 

Loosening on the acetabular side most often occurs at the bone-cement interface. Histiocyte cell membrane proliferation incited by particulate generation proceeds from the periphery of the bone-cement interface to the dome of the acetabulum with eventual loosening.Correct Answer: Bone-cement interface

 

 

1. (1805) Q1-2205:

   The best fatigue strength for the femoral component is:

    

   1) Coated stainless steel

   3) Cold-forged stainless steel

   2) Coated chromium cobalt

   5) Porous-coated stainless steel

   4) Fatigue strength is identical in all

    

   Cold-worked, cold-forged micrograin femoral components provide greater fatigue strength than original casting techniques. Coated stainless steel and coated chromium cobalt have less fatigue strength then the other answer choices.Correct Answer: Cold-forged stainless steel

    

    

2. (1806) Q1-2206:

   Femoral components made of which material have the least amount of stiffness:

    

   1) Stainless steel

   3) Titanium

   2) Chromium cobalt

   5) Porous-coated stainless steel

   4) All of the above have approximately the same amount of stiffness

    

   Titanium has one-half the material modulus, or stiffness, of chromium cobalt or stainless steel irrespective of the type of porous coating. Titanium also has a high corrosion resistance that is attributed to an oxide layer which is chemically nonreactive to the surrounding tissue.Correct Answer: Titanium

    

    

3. (1807) Q1-2207:

Cement fatigue is the main cause of loosening in a cemented femoral component. Cement is strongest in:

 

1) Extension

3) Compression

2) Tension

5) Flexion

4) Shear

 

Cement is stronger in compression than in tension. Stem designs incorporate a taper to the mid and distal stem geometry to transfer the load from the stem to the cement primarily in compression.Correct Answer: Compression

 

 

 

1) RA surface more than 1.5 (average roughness)

3) Matte finish surface

2) Grit-blasted surface

5) None of the above

4) Polished, smooth surface

 

Femoral components with polished, smooth surfaces and low RA surfaces have proved to be more durable than devices with a rougher finish.Correct Answer: Polished, smooth surface

 

 

1. (1809) Q1-2209:

   Noncemented femoral components must be able to resist translation and rotation in all of the following except:

    

   1) Translation in the axial plane

   3) Translation in the anteroposterior plane

   2) Translation in the medial-lateral plane

   5) Pivot shift test

   4) Rotation in the coronal plane

    

   Implants must resist translation in the axial, medial-lateral, and anteroposterior planes, as well as resisting rotation in the parasagittal, transverse, and coronal planes.Correct Answer: Pivot shift test

    

    

2. (1810) Q1-2210:

   Which uncemented femoral component design provides the best axial and torsional stability in the metaphyses:

    

   1) Single wedge-shaped implant

   3) Tapered implant

   2) Wedge-shaped metaphyseal-filling implant

   5) Diaphyseal-filling implant

   4) Extensively porous-coated implant

    

   The metaphysis provides axial and torsional stability for most wedge-shaped, proximally porous-coated, metaphyseal-filling implants. The other types of implants give stability in other areas than the metaphyses.Correct Answer: Wedge-shaped metaphyseal-filling implant

    

    

3. (1811) Q1-2211:

Modularity in noncemented femoral components is popular because the design:

 

1) Is associated with less loosening

3) Increases particulate debris

2) Allows more versatility in matching proximal and distal femoral geometry

5) Leads to more osteolysis

4) Leads to less osteolysis

 

Modularity in noncemented femoral components is popular because it allows more versatility in matching proximal and distal femoral geometry. However, additional research is needed to determine if particulate debris leads to osteolysis and failure.Correct Answer: Allows more versatility in matching proximal and distal femoral geometry

 

 

 

1) Provided a poor distal fit

3) Caused stress fracture at the porous-coated site

2) Increased micromotion of the implant

5) Caused excessive polyethylene wear

4) Provided channels for egress of particulate debris

 

Patch porous-coated femoral implants failed because they provided channels for the particulate debris to move distally, resulting in diaphyseal osteolysis. A poor proximal fit permits the polyethylene particulate debris to erode around the femoral component.Correct Answer: Provided channels for egress of particulate debris

 

 

1. (1813) Q1-2214:

   Which of the following is the preferred thickness for hydroxyapatite coatings:

    

   1) 5 µm

   3) 50 µm

   2) 20 µm

   5) 400 µm

   4) 200 µm

    

   Thick hydroxyapatite coatings of 200 µm or more are at risk for fracture and delamination, and thin coatings of 20 µm or less may be resorbed too quickly. The best compromise appears to be 50 µm, which is thick enough so that resorption does not take place too quickly.Correct Answer: 50 µm

    

    

2. (1814) Q1-2215:

   Periprosthetic bone loss occurs by all of the following mechanisms except:

    

   1) Stress shielding

   3) Implant extraction

   2) Osteolysis

   5) Erosion by infection

   4) Impaction grafting

    

   Stress shielding, osteolysis, and implant extraction result in bone loss and must be minimized to maintain bone stock. Impaction grafting is a technique used to increase bone stock.Correct Answer: Impaction grafting

    

    

3. (1815) Q1-2216:

Stress shielding occurs in the proximal femur secondary to:

 

1) Cemented femoral implants

3) Stiffer implants that allow more distal bone growth

2) Noncemented femoral implants

5) All of the above.

4) Modular designs

 

Stress shielding occurs secondary to cemented femoral implants, noncemented femoral implants, and stiffer, longer implants that allow more distal bone growth. Stress shielding is also related to the geometry of the implant and bone quality. Modular designs alone do not cause stress shielding.Correct Answer: All of the above.

 

 

 

1) Stem loosening

3) Bony stabilization of implant

2) Fibrous stabilization of implant

5) Stem loosening and bony stabilization of implant

4) Stem loosening and fibrous stabilization

 

Thigh pain in noncemented implants is frequently a consequence of stem loosening and fibrous stabilization. Thigh pain has not been associated with bony stabilization of the implant because there is no stem loosening if there is adequate bony stabilization.Correct Answer: Stem loosening and fibrous stabilization

 

 

1. (1817) Q1-2218:

   All of the following strategies are used to reduce the micromotion between the flexible bone of the femur and a stiff femoral implant except:

    

   1. Providing external porous coatings to the tip of the stem

      3) Tapering the stem tip

      2) Reducing contact between the tip of the stem and cortical bone

      5) Expanding the stem tip so that it compresses on the cortex

      4) Cementing the femoral component

       

      Providing external porous coatings to the tip of the stem, reducing contact between the tip of the stem and cortical bone, and tapering the stem tip are strategies that have been used to reduce micromotion. Cementing the femoral component will also reduce micromotion.Correct Answer: Expanding the stem tip so that it compresses on the cortex

       

       

2. (1818) Q1-2219:

   All of the following methods are used to reduce the modulus of elasticity of the distal stem except:

    

   1. Stems with slots

      3) Enlarging the distal stem tip

      2) Slimming and boring out the center of the distal stem

      5) Diaphyseal cutouts

      4) Hollow distal stems

       

      Stems with slots, diaphyseal cutouts, and hollow distal stems have been used to reduce stem stiffness. Enlarging the distal stem tip increases the modulus of elasticity of the distal stem.Correct Answer: Enlarging the distal stem tip

       

       

3. (1819) Q1-2220:

The major biomechanical function of the femoral component in total hip arthroplasty is to:

 

1. Optimize leg length

   3) Accomodate the femoral head

   2) Anchor the prosthetic femoral head to the femur

   5) Replace poor bone stock

   4) Equalize leg length

    

   Anchoring the prosthetic femoral head to the femur and substituting for the femoral head and neck are the major biomechanical functions of the femoral component in total hip arthroplasty. One can decrease or increase leg lengths by changing the size of a femoral component, specifically the neck length.Correct Answer: Anchor the prosthetic femoral head to the femur

    

    

    

   1. Corticosteroids

      3) Nitrogen bubbles

      2) Displaced transcervical fracture

      5) Sickle cell disease

      4) Coagulopathies

       

      Displaced transcervical fractures of the cervical neck of the femur are the most common cause of osteonecrosis of the femoral head. Although corticosteroid use, nitrogen bubbles, coagulopathies, and sickle cell disease can also cause osteonecrosis, the highest incidence is seen with displaced transcervical fractures.Correct Answer: Displaced transcervical fracture

       

       

      1. (1821) Q1-2222:

         In the United States, what percentage of primary total hip replacements are performed due to osteonecrosis:

          

         1) 3%

         3) 10%

         2) 5%

         5) 20%

         4) 15%

          

         In the United States, approximately 10% of primary total hip replacements are performed due to osteonecrosis. The majority of total hip replacements occur secondary to osteoarthritis.Correct Answer: 10%

          

          

      2. (1822) Q1-2223:

         Osteonecrosis is bilateral in what percentage of patients between 25 and 45 years of age with a diagnosis of AVN of one hip:

          

         1) 10%

         1. 30%

   2. 20%

      5) 50%

      4) 40%

       

      Adults between 25 and 45 years old are most frequently affected with osteonecrosis, and the condition is bilateral in more than 50% of patients. The condition is usually secondary to alcoholism, corticosteroid use, sickle cell disease, and coagulopathies, as opposed to transcervical neck fractures seen in the elderly.Correct Answer: 50%

       

       

      1. (1823) Q1-2224:

      All of the mechanisms listed below have been implicated in causing osteonecrosis except:

       

      1. Intravascular coagulation

   3. Embolization of fat

   1. Hemodilation of blood

      5) Sickle cells

      4) Nitrogen bubbles

       

      Factors causing intravascular coagulation or thrombosis, not hemodilation, are the most important mechanisms implicated in causing osteonecrosis.Correct Answer: Hemodilation of blood

       

       

       

      1. Excessive alcohol intake

         3) Nonsteroidal anti-inflammatory drugs (COX 1)

         2) Gout medication

         5) Nonsteroidal anti-inflammatory drugs (COX 2)

         4) Ciprofloxin administration

          

         Excessive alcohol intake and chronic steroid administration are the common factors implicated in the development of osteonecrosis. Although there have been case reports indicating nonsteroidal anti-inflammatory drugs, it is questionable if this was the cause.Correct Answer: Excessive alcohol intake

          

          

         1. (1825) Q1-2226:

            What percentage of patients exposed to heavy alcohol consumption will develop osteonecrosis:

             

            1) 5%

            3) 15%

            2) 10%

            5) 25%

            4) 20%

             

            Less than 5% of patients exposed to heavy alcohol consumption develop osteonecrosis.Correct Answer: 5%

             

             

         2. (1826) Q1-2227:

            What percentage of patients exposed to high dosages of corticosteroids develop avascular necrosis:

             

            1) 10%

   2. 30%

   1. 20%

      5) 50%

      4) 40%

       

      Five percent to 10% of patients who receive high doses of corticosteroids develop avascular necrosis. Why only a small percentage of patients develop avascular necrosis is poorly understood, and there may be some genetic predisposition.Correct Answer: 10%

       

       

      1. (1827) Q1-2228:

         Subtle coagulation defects are found in what percentage of patients with osteonecrosis:

          

         1) 20%

   2. 40%

2. 30%

   5) 70%

   4) 50%

    

   Seventy percent of patients with osteonecrosis have some subtle coagulation defect.Correct Answer: 70%

    

    

   1. (1828) Q1-2229:

      The radiolucent crescent sign on radiographs of the hip:

       

      1. Is present only in the stage II disease avascular necrosis

3. Is caused by collapse of the subchondral trabeculae

1. Occurs in the articular cartilage

   5) Is present only after articular cartilage loss

   4) Is more clearly seen on magnetic resonance imaging

    

   The crescent sign is caused by subchondral trabeculae collapse before flattening of the articular surface. The success of core decompression is markedly diminished after this finding is seen on radiographs.Correct Answer: Is caused by collapse of the subchondral trabeculae

    

   1. (1829) Q1-2230:

      The articular cartilage of the femoral head remains intact until after trabecular collapse because:

       

      1. Nutrition comes from the metaphyseal bone

2. Nutrition comes from the epiphysis

1. Nutrition comes from the synovial fluid

   5) Nutrition comes from the diaphysis by way of vessels in the metaphysis

   4) Nutrition comes from the synovial membrane

    

   Cartilage receives its nutrition through the synovial fluid. Only after collapse of the head is articular cartilage subjected to abnormal mechanical pressures that lead to degeneration.Correct Answer: Nutrition comes from the synovial fluid

    

    

   1. (1830) Q1-2231:

      On radiograph, what stage of osteonecrosis is associated with a dense necrotic lesion with a sclerotic border but no crescent sign:

       

      1. Stage I

2. Stage III

1. Stage II

   5) Stage V

   4) Stage IV

    

   Stage II of osteonecrosis has good cartilage space without collapse, and a dense necrotic lesion with sclerotic border but does not have a crescent sign. Stage I is detected on magnetic resonance imaging, and stages III and IV are advanced forms of osteonecrosis.Correct Answer: Stage II

    

    

   1. (1831) Q1-2232:

      The early stages of osteonecrosis are best detected by:

       

      1. Anteroposterior and lateral radiographs

2. Magnetic resonance image (MRI)

1. Bone scans

   5) Single photon computed tomography

   4) Computed tomography

    

   If present, radiographic changes are detected by MRI in more than 90% of cases. MRI remains the most sensitive test for osteonecrosis and becomes positive before changes are present on the roentgenogram.Correct Answer: Magnetic resonance image (MRI)

    

    

   1. (1832) Q1-2233:

   What percentage of hips diagnosed clinically with osteonecrosis go on to femoral head collapse:

    

   1) 30%

2. 50%

1. 40%

   5) 80%

   4) 70%

    

   Approximately 70% of hips diagnosed clinically with osteonecrosis go on to femoral head collapse. The majority of hips progress to the severe form of the disease and will ultimately require total joint arthroplasty.Correct Answer: 70%

    

    

    

   1. Direct current

2. Pulsing electromagnetic fields

1. Capacitive coupling

   5) Concurrent bone grafting

   4) Indirect current

    

   The results of a multicenter study show promising results with pulsing electromagnetic fields. Pulsing electromagnetic fields were found effective as a symptomatic management in precollapsed lesion and as effective as core decompression.Correct Answer: Pulsing electromagnetic fields

    

    

   1. (1834) Q1-2236:

      Core decompression for osteonecrosis of the femoral head does not act through which of the following mechanisms:

       

      1. Decreasing the intraosseous pressure

         3) Stimulating the repair process

         2) Opening channels for vascular ingrowth

         5) Increasing vascularity to the avascular area

         4) Increasing structural integrity

          

         Core decompression is affected by a number of mechanisms including decreasing the intraosseous pressure, opening channels for vascular ingrowth, and stimulating the repair process through increased vascularity. Core decompression does not increase structural integrity of the area.Correct Answer: Increasing structural integrity

          

          

   2. (1835) Q1-2237:

      Urbaniak and associates reported a success rate of treating osteonecrosis before collapse:

       

      1) 10%

2. 50%

1. 30%

   5) 90%

   4) 70%

    

   Urbaniak and associates reported a success rate of 70% with mild collapse and 80% before collapse. Their results have not been duplicated as yet. The results of their study are much better than those reported with fibular graft.Correct Answer: 70%

    

    

   1. (1836) Q1-2238:

   The incidence of deep infection complicating primary total hip arthroplasty is:

    

   1) 0.25%

2. 1%

1. 0.5%

   5) 3%

   4) 2%

    

   The incidence of deep infection in primary total hip replacement is 1%. After revision hip surgery, the percentage increases 3% to 4%. Repeated revisions are associated with increasing infection rates.Correct Answer: 1%

    

    

    

   1. Staphylococcus aureus

2. Staphylococcus epidermidis

1. Streptococcus

   5) Salmonella typhi

   4) Escherichia coli

    

   Staphylococcus epidermidis accounts for 50% to 75% of all arthroplasty infections. This is the most common organism cultured from the skin of preoperative patients.Correct Answer: Staphylococcus epidermidis

    

    

   1. (1838) Q1-2240:

      Organisms survive on biosynthetic surfaces, such as total hips, because of:

       

      1. Sulphate molecules on the surface

         3) Polysaccharide biofilm on the surface

         2) Their natural occurrence in the human body

         5) Mucopolysaccharide present in the synovial fluid

         4) They are protected by the sodium hyalurinate

          

         Antibiotic resistance, the organismâs ability to form a glycocalyx or polysaccharide biofilm, and a slime layer enable the organism to survive on implants. This is one of the reasons why it is difficult to clear up an infection using only antibiotics.Correct Answer: Polysaccharide biofilm on the surface

          

          

   2. (1839) Q1-2241:

      Preoperatively, what percentage of patients undergoing total hip replacement have methicillin-resistant Staphylococcus aureus (MRSE) organisms on their skin:

       

      1) 10%

2. 35%

1. 25%

   5) 65%

   4) 40%

    

   Preoperatively, 25% of skin swabs taken in 100 patients undergoing total hip replacement were MRSE resistant. This is probably a direct result of the overuse of antibiotics by practicing physicians.Correct Answer: 25%

    

    

   1. (1840) Q1-2242:

      After analyzing 148,359 primary total hip arthroplasties, the Swedish Registry found the lowest risk of revision was:

       

      1. Ventilated suits

2. Palacos-gentamicin cement

1. Laminar flow

   5) Palacos cement

   4) Sugeon dependent

    

   The Swedish Registry found the lowest risk of revision was in patients who had palacos-gentamicin cement. No effect was found with ventilated suits or laminar flow.Correct Answer: Palacos-gentamicin cement

    

    

   1. (1841) Q1-2243:

      The erythrocyte sedimentation rate (ESR) returns to normal how long after a total hip replacement:

       

      1. 6 weeks

2. 6 months

1. 2 months

   5) 1 year

   4) 9 months

    

   The ESR takes more than a year to return to normal after a total hip replacement.Correct Answer: 1 year

    

   1. (1842) Q1-2244:

      An erythrocyte sedimentation rate (ESR) of what level is considered a good cutoff for guiding an index of suspicion for infection:

       

      1. 10 mm/hr

2. 30 mm/hr

1. 20 mm/hr

   5) 60 mm/hr

   4) 40 mm/hr

    

   With an ESR of 30 mm/hr to 35 mm/hr, sensitivities have been reported from 0.60 to 0.96 and specificities from 0.65 to

   1.00.Correct Answer: 30 mm/hr

    

    

   1. (1843) Q1-2245:

      C-reactive protein (CRP) peaks 48 hours postoperatively and rapidly declines to normal in      weeks without persistent infection or inflammation.

       

      1. 1 to 2

2. 4 to 6

1. 2 to 3

   5) 8 to 10

   4) 5 to 7

    

   The CRP returns to normal in 2 to 3 weeks without persistent infection or inflammation. High levels beyond 2 to 3 weeks suggest persistent infection.Correct Answer: 2 to 3

    

    

   1. (1844) Q1-2246:

      As the most direct and predictable preoperative diagnostic test for hip infection, the false-positive rate for hip aspiration is:

       

      1) 0%

2. 15% to 25%

1. 0% to 15%

   5) 40% to 50%

   4) 25% to 40%

    

   Hip aspiration has a false-positive rate of 0% to 15%. Many authors have warned against its routine use before revision surgery.Correct Answer: 0% to 15%

    

    

   1. (1845) Q1-2247:

   What levels of polymorphonuclear leukocytes (PMN) per high-power field (HPF) are inconsistent with infection when performing intraoperative frozen sections of total joint replacement:

    

   1. No value as predictor

2. <8 PMN/HPF

   1. <5 PMN/HPF

      5) <15 PMN/HPF

      1. <10 PMN/HPF

          

         When using <5 PMN/HPF as a cut off for an infected total joint, the sensitivity was 100% and specificity was 96%.Correct Answer:

         <5 PMN/HPF

          

          

          

         1) 5%

         3) 15%

         2) 10%

      2. 25%

3. 20%

    

   The false-positives results are reported to be between 6% and 13% and are probably related to break in sterility while obtaining, transferring, and plating the specimen.Correct Answer: 10%

    

    

   1. (1847) Q1-2249:

      It is recommended to use which of the following drugs in patients who are too sick for a surgical procedure and antibiotic suppression:

       

      1) Amikacin

      3) Imipenem

      2) Ofloxacin

      5) Rifampin

      4) Vancomycin

       

      Amikacin, ofloxacin, imipenem, and vancomycin are only effective against growing bacteria. Rifampin, which affects messenger RNA synthesis, is the only drug capable of inducing strong enough pharmacodynamic effects to inhibit both growing and nongrowing Staphylococcus epidermidis.Correct Answer: Rifampin

       

       

   2. (1848) Q1-2250:

      The highest dislocation rate for total hip arthroplasty is associated with which of the following surgical approaches:

       

      1) Anterior approach

      3) Transtrochanteric approach

      2) Posterior approach

      5) All of the approaches have the same incidence of dislocation.

      4) Hardinge approach

       

      The anterior approach has a dislocation rate of 3.5%, posterior approach 4.6%, and transtrochanteric approach 7.6%.Correct Answer: Transtrochanteric approach

       

       

   3. (1849) Q1-2251:

   The prevalence of dislocation following a primary bipolar hemiarthroplasty is:

    

   1) The same as primary total hip arthroplasty

   3) Lower than primary total hip arthroplasty

   2) Higher than primary total hip arthroplasty

   5) Not dependent on the surgical approach

   4) Higher than semipolar hemiarthroplasty

    

   The prevalence of dislocation following a primary bipolar hemiarthroplasty is 1.5% compared to 3.5% or higher (depending on the surgical approach) for a total hip arthroplasty.Correct Answer: Lower than primary total hip arthroplasty

    

    

    

   1) Gender

   3) Acute femoral neck fracture

   2) Height

   5) Previous knee surgery

   4) Weight

    

   In addition to an acute femoral neck fracture, other patient-related factors associated with dislocation after total hip arthroplasty include patients older than 80 years and previous hip surgery.Correct Answer: Acute femoral neck fracture

    

    

   1. (1851) Q1-2253:

      Which of the following factors is associated with the highest incidence of total hip dislocation after surgery:

       

      1) Acetabular component malposition in a vertical position

      3) Acetabular component in a retroverted position

      2) Femoral component malposition in a varus position

      5) Femoral component malposition in a valgus position

      4) Muscular imbalance

       

      A computed tomography study of dislocated total hip arthroplasties (THAs) compared to uncomplicated THAs showed no difference between the alignment of the components in either group. Muscular imbalance rather than malposition of components was the major factor in determining dislocation.Correct Answer: Muscular imbalance

       

       

   2. (1852) Q1-2254:

      Which of the following is associated with an increased risk of dislocation after a total hip arthroplasty:

       

      1) Elevated rim liner

      3) 32-mm femoral head

      2) Skirt (reinforcement of the bone at the neck)

      5) Ceramic-on-ceramic hip arthroplasty

      4) Metal-on-metal hip arthroplasty

       

      There is an increased risk of dislocation with a skirt. The elevated rim liner decreases the risk of a dislocation, and a 32-mm femoral head may or may not have a decreased rate of dislocation.Correct Answer: Skirt (reinforcement of the bone at the neck)

       

       

   3. (1853) Q1-2255:

   Which of the following factors is not associated with dislocation of a total hip arthroplasty:

    

   1) Infection

   3) Profound weight loss

   2) Trauma

   5) Gender

   1. Chronic illness

       

      Infection, trauma, and profound weight loss are associated with an increased risk of dislocation. Infection with septic fluid accumulation stretches the capsule. Trauma from a fall is a direct cause of dislocation, and profound weight loss with its accompanying loss of muscle mass (as a result of cancer or chronic illness).Correct Answer: Gender

       

       

       

      1) 5%

      3) 20%

      2) 10%

   2. 50%

   4) 33%

    

   One-third of patients with a dislocated total hip arthroplasty will have recurrent dislocations. This number is potentially minimized by having patients wear an abduction splint for 6 to 12 weeks after the initial dislocation.Correct Answer: 33%

    

    

   1. (1855) Q1-2257:

      The highest incidence of deep infection in total hip arthroplasty is associated with what patient group:

       

      1) Patients with rheumatoid arthritis

      3) Patients with diabetes mellitus

      2) Patiens with psoriatic arthritis

      5) Women

      4) Patients with avascular necrosis

       

      The highest incidence of deep infection is in patients with diabetes mellitus (5.6%) compared to patients with rheumatoid arthritis (1.2%) and patients with psoriatic arthritis (5.5%). Any immune-compromised patient is at a higher risk for infection following total hip arthroplasty.Correct Answer: Patients with diabetes mellitus

       

       

   2. (1856) Q1-2258:

      The most common complication after total hip arthroplasty is:

       

      1. Infection

         3) Deep vein thrombosis

         2) Dislocation

         5) Urinary tract infection

         4) Pulmonary embolism

          

         The incidence of deep vein thrombosis is as high as 70% and as low as 8%.Correct Answer: Deep vein thrombosis

          

          

   3. (1857) Q1-2259:

      The incidence of deep vein thrombosis is reported to be highest on postoperative day:

       

      1) 1

      1. 3

         1. 2

4. 5

1. 4

    

   The incidence of deep vein thrombosis is reported to be highest on postoperative day 4.Correct Answer: 4

    

    

   1. (1858) Q1-2260:

   Which of the following is the gold standard to rule out a pulmonary embolism:

    

   1) Radiograph

   3) Electrocardiogram

   2) Ventilation perfusion scan

   5) Pulmonary angiogram

   1. Ultrasonography

       

      The gold standard for detecting pulmonary embolus is the pulmonary angiogram, although a combination chest radiograph, ventilation perfusion scan, and electrocardiogram is usually performed.Correct Answer: Pulmonary angiogram

       

      when it is administered intravenously in the first 6 days after total hip arthroplasty:

       

      1) 5%

      3) 25%

      2) 15%

   2. 60%

   4) 45%

    

   The risk of bleeding complications from therapeutic anticoagulation is high in the immediate postoperative period with a 45% incidence.Correct Answer: 45%

    

    

   1. (1860) Q1-2262:

      All of the following conditions are associated with an increased risk of heterotopic ossification after total hip arthroplasty except:

       

      1) Ankylosing spondylitis

      3) Posttraumatic arthritis

      2) Forestier disease

      5) Rheumatoid arthritis

      4) Men with bilateral osteophytic osteoarthritis

       

      Ankylosing spondylitis, Forestier disease, posttraumatic arthritis, and men with bilateral osteophytic osteoarthritis are associated with an increased risk of heterotopic ossification following total hip arthroplasty.Correct Answer: Rheumatoid arthritis

       

       

   2. (1861) Q1-2263:

      What is the lowest dose of radiation that is effective in preventing heterotopic bone formation after total hip arthroplasty:

       

      1. 1000 Rads

         3) 3000 Rads

         2) 2000 Rads

         5) 5000 Rads

         4) 4000 Rads

          

         A protocol of 1000 Rads is as effective as 2000 Rads.Correct Answer: 1000 Rads

          

          

   3. (1862) Q1-2264:

      The incidence of trochanteric nonunion after greater trochanteric osteotomy in primary total hip arthroplasty is:

       

      1) 5%

      1. 15%

         1. 10%

2. 25%

1. 20%

    

   There is a 5% incidence of trochanteric nonunion after greater trochanteric osteotomy in primary total hip arthroplasty.Correct Answer: 5%

    

    

   1. (1863) Q1-2265:

   The main purpose of a trochanteric osteotomy is to:

    

   1) Decrease the operative time

   3) Lateralize the adduction mechanism

   2) Enhance exposure

   5) Decrease the blood loss

   4) Prevent dislocation

    

   Enhancing exposure and lateralizing the abductor mechanism are the main reasons for performing an osteotomy. The osteotomy must be balanced against the increased blood loss, operative time, and slower rehabilitation.Correct Answer: Enhance exposure

    

    

    

   1) Excessive head-stem offset

   3) Size of stem

   2) Modularity

   5) Inadequate cross-sectional area

   4) Material strength

    

   All of the factors, except modularity, contribute to early stem breakage in the first generation of total hips.Correct Answer: Modularity

    

    

   1. (1865) Q1-2267:

      In early first-generation total hip implant designs, fatigue fractures occurred in which of the following areas of the femoral stem:

       

      1. Posterolateral

         3) Anterolateral

         2) Posteromedia

         5) Anterior

         4) Anteromedial

          

         In early first-generation total hip implant designs, fatigue fractures occurred anterolaterally because that was the area of greatest tension. Fatigue fractures are less common in compression.Correct Answer: Anterolateral

          

          

   2. (1866) Q1-2268:

      Total hip arthroplasty for a congenital dislocated hip has a nerve injury incidence of:

       

      1) 5%

      1. 15%

         1. 10%

2. 25%

1. 20%

    

   The incidence of nerve injury following congenital dislocated hip is 5.2% compared to 0.6% to 3.7% for routine total hip arthroplasty.Correct Answer: 5%

    

    

   1. (1867) Q1-2269:

      Which of the following arteries is at the greatest risk for vascular injury during a total hip arthroplasty for protrusio acetabuli:

       

      1) Femoral artery

      3) Common iliac artery

      2) Obturator artery

      5) Popliteal artery

      4) Peroneal artery

       

      The common and superficial iliac arteries are most at risk in patients with protrusio acetabuli. The obturator is not at risk when removing the transverse ligament from the inferior margin of the cup.Correct Answer: Common iliac artery

       

       

   2. (1868) Q1-2270:

   Debonding (separation of the femoral stem from the surrounding cement mantle) is caused by:

    

   1) Tension forces from muscle contraction

   3) Torsional forces in retroversion

   2) Strain at the cement-metal interface

   5) Compression forces from muscle contraction

   4) Rotational forces in anteversion

    

   When arising from a chair or climbing the stairs, the stem shifts to a more retroverted position within the cement mantle secondary to the peak torsional forces in retroversion.Correct Answer: Torsional forces in retroversion

    

   when they are pressed together under load:

    

   1) Abrasion

   3) Adhesion

   2) Fatigue

   5) Compression

   4) Cohesion

    

   Abrasion, fatigue, and adhesion are fundamental wear mechanisms. Adhesion is the binding of the surfaces when they are pressed together under load.Correct Answer: Adhesion

    

    

   1. (1870) Q1-2274:

      The volumetric wear of polyethylene is greatest with what size head:

       

      1) 32 mm

      3) 26 mm

      2) 28 mm

      5) 20 mm

      4) 22 mm

       

      The volumetric wear of polyethylene is proportional to the size of the femoral head and larger femoral heads have a longer sliding distance that results in greater wear.Correct Answer: 32 mm

       

       

   2. (1871) Q1-2275:

      Preparing and sterilizing polyethylene with gamma radiation:

       

      1) Increases the molecular weight of the material

      3) Increases recombination of the polyethylene particles

      2) Decreases free radicals that can react with carbon dioxide

      5) Increases free radicals that react with carbon dioxide

      4) Stabilizes free radicals that react with carbon dioxide

       

      Gamma radiation prevents recombination, decreases the molecular weight of the material, and increases free radicals that react with carbon dioxide to form ketone esters and carbolic acid groups.Correct Answer: Increases free radicals that react with carbon dioxide

       

       

   3. (1872) Q1-2276:

   In osteolysis, small wear debris is broken down and ingested by:

    

   1) Polymorphonuclear neutrophils

   3) Macrophages

   2) Foreign body giant cells

   5) Osteoblasts

   1. Histiocytes

       

      Small wear debris is phagocytosed by macrophages. Large wear debris is surrounded by foreign body giant cells.Correct Answer: Macrophages

       

      generated with each gait cycle is:

       

      1) 500

      3) 100,000

      2) 50,000

   2. 500,000

   4) 300,000

    

   The average number of particles generated with each gait cycle is approximately 500,000.Correct Answer: 500,000

    

    

   1. (1982) Q1-2396:

      All of the following are consequences of using too large of a femoral component in total knee replacement except:

       

      1) Overstuffing the joint

      3) Decreasing range of motion

      2) Limitation of quadriceps excursion

      5) Increasing range of motion

      4) A cause of postoperative knee pain

       

      Too large of a femoral component in total knee replacement may result in overstuffing the joint, limiting quadriceps excursion, and decreasing range of motion.Correct Answer: Increasing range of motion

       

       

   2. (1983) Q1-2397:

      It is acceptable for the joint line to be elevated how many millimeters during total knee replacement surgery:

       

      1) 0 mm

      3) 2 mm

      2) 1 mm

      5) 4 mm

      4) 3 mm

       

      It is acceptable for the joint line to be raised approximately 2 mm during total knee replacement, but any higher elevation may create mid-flexion laxity.Correct Answer: 2 mm

       

       

   3. (1984) Q1-2399:

   When performing a total knee replacement and you are in between sizes, it is best to:

    

   1) Downsize the femoral component and recut the femur in 3° of flexion

   3) Upsize the prosthesis

   2) Downsize the femoral component and recut the femur in 6° of flexion

   5) Upsize the prosthesis and recut the femur in 6° of extension.

   4) Downsize the femoral component and minimalize notching the anterior cortex

    

   An option for downsizing without notching is to recut the distal femur in slight flexion, applying a modified distal cutting block that will add several degrees of flexion to the distal cut. Recutting the distal femur in slight (3°) flexion has the following rationale: the normal trochlear flange of most components already diverges approximately 3°. By adding another 3° of flexion one can use a smaller component because the trochlear flange will now diverge 6°, avoiding a notch in the anterior cortex. The advantage is that the posterior condylar resection remains anatomic and the level of the joint line is preserved.Correct Answer: Downsize the femoral component and recut the femur in 3° of flexion

    

    

    

   1) Femoral cam

   3) Conforming articular geometry

   2) Polyethylene post on the tibial component

   5) Constrained hinge

   4) Use of cement

    

   The primary features of posterior stabilized total knee devices include femoral cam, polyethylene post on the tibial component, conforming articular geometry, and use of cement. These characteristics have produced total knee prostheses with unsurpassed clinical survivorship and patient function.Correct Answer: Constrained hinge

    

    

   1. (1986) Q1-2401:

      The clinical survivorship of posterior stabilized prostheses at 10 years is:

       

      1) 80%

      3) 90%

      2) 85%

      5) 98%

      4) 95%

       

      The clinical survivorship of posterior stabilized prostheses is spectacular by any standards with a success rate of approximately 95% of prostheses that were free from revision due to aseptic loosening at 10 to 15 years.Correct Answer: 95%

       

       

   2. (1987) Q1-2402:

      If the posterior cruciate ligament (PCL) is too loose in flexion in a cruciate-retaining prosthesis, the result is:

       

      1) Flexion gap

      3) Increased posterior sliding of the femorotibial contact point

      2) Extension gap

      5) Hyperextension deformity

      4) Restricted flexion

       

      If the PCL is too loose, anterior translation of the femorotibial contact point will occur, whereas if the PCL is too tight, flexion will be restricted.Correct Answer: Flexion gap

       

       

   3. (1988) Q1-2403:

   If the posterior cruciate ligament (PCL) is too tight in flexion in a cruciate-retaining total knee replacement, the result is:

    

   1) Flexion gap

   3) Restricted flexion

   2) Restricted extension

   5) Increased flexion

   4) Hyperextension deformity

    

   If the PCL is too loose, anterior translation of the femorotibial contact point will occur, whereas if the PCL is too tight, flexion will be restricted.Correct Answer: Restricted flexion

    

   surgeon should consider:

    

   1) Using a smaller tibial insert

   3) Resecting more femur in extension

   2) Resecting more tibial bone

   5) Increasing the size of the femoral component

   4) Using a deep dish insert

    

   Hofmann and colleagues reviewed their use of ultracongruent polyethylene over 7 years in 100 patients who underwent PCL-substituting total knee arthroplasties. Fifty-three cases were primary and 47 were revisions. There were no cases of anteroposterior (AP) instability in either revision or primary cases when a deep-dish polyethylene was inserted. The incidence of AP instability using standard inserts was 2% to 3%.Correct Answer: Using a deep dish insert

    

    

   1. (1990) Q1-2405:

      Patellar clunk syndrome is caused by:

       

      1) Too large a patellar component

      3) Fibrous tissue build-up occurring in a large intercondylar notch of the prosthesis

      2) Too small a patellar component

      5) Dislocation of the quadriceps mechanism over a malrotated femoral component

      4) Too large a femoral component

       

      Patellar clunk occurs from a large intercondylar notch of the prosthesis, which causes fibrous tissue build-up proximally and can result in 1% to 2% of patients requiring arthroscopic debridement.Correct Answer: Fibrous tissue build-up occurring in a large intercondylar notch of the prosthesis

       

       

   2. (1991) Q1-2406:

      All of the following is a reported complication of posts in posterior cruciate-retaining prostheses except:

       

      1) Patellar fracture

      3) Patellar clunk syndrome

      2) Knee dislocation

      5) Flexion instability

      4) Post fracture

       

      Complications reported with the use of posts include patellar fractures, knee dislocations, and patellar clunk syndrome.Correct Answer: Flexion instability

       

       

   3. (1992) Q1-2407:

   In a posterior cruciate-retaining prosthesis, most stress at the posterior cruciate ligament occurs in:

    

   1) Extension

   3) 30° flexion

   2) 15° flexion

   5) 90° flexion

   4) 45° flexion

    

   A consequence of the kinematics of a crossed four-bar link is the phenomenon of rollback, that is, the progressive movement of the femoral condyle posteriorly relative to the tibia with increasing flexion.Correct Answer: 90° flexion

    

    

    

   1) Stair climbing

   3) Walking on uneven ground

   2) Rising from a chair

   5) Full extension

   4) Stepping up a curb

    

   Cruciate ligament deficiency can lead to abnormalities during stair climbing, rising from a chair, and walking on uneven ground.Correct Answer: Full extension

    

    

   1. (1994) Q1-2410:

      C-reactive protein should return to normal how many weeks after a total knee replacement surgery:

       

      1) 1 week

      3) 3 weeks

      2) 2 weeks

      5) 12 weeks

      4) 6 weeks

       

      C-reactive protein should return to normal within 3 weeks of surgery.Correct Answer: 3 weeks

       

       

   2. (1995) Q1-2411:

      One can best avoid bone stiffness after total knee replacement (TKR) by:

       

      1) Careful attention to proper sizing of the components

      3) Maintenance of physiologic soft tissue tension in complete extension and at 90° of flexion

      2) Restoration of the mechanical axis and anatomic joint line

      5) None of the above

      4) All of the above

       

      Avoiding stiffness after TKR is easier than managing the stiff total knee. Careful attention to proper sizing of components, restoration of the mechanical axis and anatomic joint line, and maintenance of physiologic soft-tissue tension in complete extension and at 90° of flexion will minimize the risk of stiffness following TKR.Correct Answer: All of the above

       

       

   3. (1996) Q1-2412:

      Flexion contractures after total knee replacement are best treated by:

       

      1. Manipulation

         3) Dynamic extensor splint

         2) Physical therapy

         5) All of the above

         4) Physical therapy, and dynamic extensor splint

          

         Flexion contractures are treated with physical therapy and the use of a dynamic extension splint at night.Correct Answer: Physical therapy, and dynamic extensor splint

          

          

   4. (1997) Q1-2413:

   The incidence of periprosthetic fracture about total knee replacement is:

    

   1) 0.2%

   1. 5%

      1. 3%

2. 9%

1. 7%

    

   Periprosthetic fractures about total knee arthoplasty (TKA) are relatively rare (0.5% to 3%).Correct Answer: 3%

    

    

    

   1) Less than 0.1 µm

   3) 1 µm to 2 µm

   2) 0.1 µm to 0.5 µm

   5) Larger than 3 µm

   4) 2 µm to 3 µm

    

   Studies have shown that cross-linked polyethylenes are stiffer and weaker than conventional polyethylene, and wear debris particles generated usually are less than 1 µm (0.1 µm to 0.5 µm), which is the most biologically active particle size.Correct Answer: 0.1 µm to 0.5 µm

    

    

   1. (1999) Q1-2415:

      Which of the following is the most common cause for revising a total hip arthroplasty (THA) when polyethylene is used:

       

      1) Infection

      3) Debris-associated osteolysis

      2) Thigh pain

      5) Chronic dislocation

      4) Wear

       

      Debris-associated osteolysis is the most common cause for revision THA when polyethylene is used. Chronic dislocation, thigh pain, wear, and infection are less common causes for revision.Correct Answer: Debris-associated osteolysis

       

       

   2. (2000) Q1-2416:

      Which of the following bearing surfaces has the lowest rate of wear in total hip arthroplasty:

       

      1) Polyethylene-metal bearings

      3) Ceramic-metal bearings

      2) Metal-metal bearings

      5) Alumina ceramic-ceramic bearings

      4) Ceramic-polyethylene bearings

       

      According to retrieval studies of Clarke and colleagues, alumina ceramic-ceramic bearings have the lowest rate of wear of any bearing surface.Correct Answer: Alumina ceramic-ceramic bearings

       

       

   3. (2001) Q1-2417:

      Staphylococcus epidermidis adheres:

       

      1) More strongly to polyethylene

      3) Similarly to both polyethylene and alumina ceramic

      2) More strongly to alumina ceramic

      5) More strongly to polymethylmethacrylate

      4) This has not been studied in a laboratory setting.

       

      Staphylococcus epidermidis adheres 2.5 times more strongly to high density polyethylene than alumina ceramic.Correct Answer: More strongly to polyethylene

       

       

   4. (2002) Q1-2418:

      The wear rate of ceramic-ceramic bearings in total hip arthroplasty is:

       

      1) 0.05 to 0.06 mm/year

      3) 0.03 to 0.02 mm/year

      2) 0.04 to 0.05 mm/year

      5) Too small to measure

      4) 0.01 to 0.02 mm/year

       

      The wear rate of ceramic-ceramic bearing surfaces in a 10-year follow-up was observed to be 0.01 mm/year.Correct Answer:

      0.01 to 0.02 mm/year

       

   5. (2003) Q1-2419:

      Which of the following observations concerning metal-metal prostheses is not true:

       

      1) Low incidence of osteolysis

      3) There is a theoretical concern of cancer

      2) There is concern about increased metal ions in the body

      5) High incidence of osteolysis

      4) Hypersensitivity

       

      The controversies with metal-metal total hip replacement relate to increased metal ions. In Europe, Hans Willert reported a 0.5% prevalence of hypersensitivity to metal-metal (personal communication, January 2001).

       

      One advantage of metal-on-metal total hip replacement is a low incidence of osteolysis. Osteolysis in the cemented cup and the modular cup series has been better than that observed with standard polyethylene acetabular components.

       

      There also is a theoretical concern of cancer. The 20-year studies from Scandinavia (particularly Finland) have not found any positive correlation to cancer.Correct Answer: High incidence of osteolysis

       

       

   6. (2004) Q1-2420:

      The best predictor for the necessity of blood transfusion in total knee replacement is:

       

      1. Preoperative hemoglobin

         3) Use of a hemovac

         2) Operative time

         5) Surgical approach

         4) Rheumatoid arthritis

          

         The biggest predictor for transfusion is the preoperative hemoglobin. There is a 69% chance of an allogenic transfusion if the hemoglobin is less than 13 g/dL and only a 13% chance if more than 15 g/dL.Correct Answer: Preoperative hemoglobin

          

          

   7. (2005) Q1-2421:

      A patient undergoing a total knee replacement with a preoperative hemoglobin >15 g/dL has what chance of requiring a transfusion:

       

      1) 5%

      1. 20%

         1. 10%

2. 40%

1. 30%

    

   There is a 69% chance of an allogenic transfusion if the hemoglobin is less than 13 g/dL and only a 13% chance if more than 15 g/dL. A surgeon must weigh the risks when lowering the preoperative hemoglobin below this level with autologous donation 1 or 2 weeks before surgery.Correct Answer: 10%

    

    

   1. (2006) Q1-2422:

   The most effective method of reducing deep infection in total joint replacement is:

    

   1) Antibiotic bone cement

   3) Systemic antibiotics

   2) Antibiotic bone cement plus systemic antibiotics

   5) Adequate skin preparation

   4) No antibiotics

    

   The use of antibiotic bone cement plus systemic antibiotics is the most effective strategy in reducing deep infection. This is followed by the use of systemic antibiotics alone, antibiotic bone cement alone, and no antibiotics.Correct Answer: Antibiotic bone cement plus systemic antibiotics

    

   Which of the following bone cements is associated with the lowest risk ratio for revision hip surgery:

    

   1) Sulfix

   3) CMW

   2) Simplex

   5) Palacos gentamicin

   4) Palacos

    

   Malchau and colleagues also performed Poisson modeling, assessing the risk of deep infection in revision surgery using different types of bone cement. Using Sulfix bone cement (Sulzer, Winterhur, Switzerland) as the numerator, the investigators assessed Simplex (Stryker Howmedica Osteonics, Allentown, NJ), CMW (Johnson & Johnson DePuy, Warsaw, Ind), Palacos (Merck/Biomet, Warsaw, Ind), and Palacos gentamicin (Merck/Biomet) bone cements. They developed a risk ratio for revision using any of these bone cements. Palacos gentamicin bone cement was associated with the lowest risk ratio for revision.Correct Answer: Palacos gentamicin

    

    

    

   1. (2316) Q1-2769:

      Early catastrophic failure of the precoat stem was due to:

       

      1. A thin cement mantle

         3) Excessive residual bone

         2) Use of low viscosity cement

         5) Proximal debonding associated with laser etching of the identifying numbers and letters on the stem

         4) Proximal debonding

          

         The catastrophic failure of the precoat stem was due to proximal debonding associated with laser etching of the identifying numbers and letters on the stem of the prosthesis. Virtually all reported stem failures occurred in left hips because the laser etching caused a local stress concentration effect on the higher stress anterior surface.Correct Answer: Proximal debonding associated with laser etching of the identifying numbers and letters on the stem

          

          

   2. (2322) Q1-2776:

   Mallet injuries with greater than    percent of the articular surface involved and palmar subluxation as a result will most likely require surgical intervention:

    

   1) 30

   1. 10

      1. 70

2. 90

1. 50

 

Type IVC injuries include distal phalanx base fractures involving more than 50% of the articular surface. Most surgeons feel that accurate reduction is mandatory to prevent joint deformity, secondary arthritis, and stiffness.Correct Answer: 50

 

 

 

 

 

Slide 1

A 70-year-old man has difficulty ambulating following a knee replacement. The lateral radiograph of the knee is shown (Slide). The most likely cause of the disability is:

 

1. Lateral patellar instability

3) Quadriceps tendon rupture

2) Patellar tendon rupture

5) Axial instability

4) Flexion instability

 

Patients may present with severe knee pain after a mild traumatic event. Patients may have the inability to extend the knee or walk. Laxity in flexion (flexion instability) can result in dislocation of the femorotibial articulation. The cam of the femoral component rides up and over the top of the post of the tibial polyethylene insert. The dislocation is usually the result of a traumatic episode.

 

Flexion instability occurs in about 1% to 2% of knee replacements when the knee is not properly balanced following a replacement. The extension and flexion gap must be equal. When balancing a knee, especially one that is tight in extension, the surgeon may choose to place a smaller tibial polyethylene component to achieve full extension with resulting instability of the knee in flexion because the knee flexion gap is larger than the polyethylene insert.

 

Treatment of flexion instability in posterior stabilized knee replacements can be nonoperative with casting or bracing initially. Two-thirds of patients can be managed successfully nonoperatively. If symptoms persist, revision to a larger polyethylene component can be very effective. If the knee remains unstable, revision to a more constrained prosthesis may be necessary.Correct Answer: Flexion instability

 

 

311. (2433) Q1-2894:

While performing posterior cruciate sacrificing knee replacement surgery, the surgeon notes a 15° flexion contracture during trial reduction after the bone cuts and soft tissue balancing. The best option is:

 

1) Placement of a smaller polyethylene insert

3) Resection of additional bone from the distal femur

2) Resection of additional bone from the proximal tibia

5) Accepting the contracture and applying an extension cast postoperatively

4) Resection of additional bone from the proximal tibia and distal femur

 

This is a common problem. Selection of a smaller polyethylene spacer results in a correction of the flexion contracture but also results in flexion instability as the flexion gap will be larger than the extension gap. First, surgeons should remove any posterior osteophytes from the distal femur. Second, the posterior capsule should be incised. If both of these maneuvers fail to correct the contracture, the surgeon should remove additional bone from the distal femur. The joint line may be raised up to 8 mm when performing posterior stabilized arthroplasties without compromising the result.Correct Answer: Resection of additional bone from the distal femur

 

 

When performing total knee replacement surgery, the following statement is true:

 

1) The distal femoral cut only effects the extension gap.

3) The proximal tibia cut only effects the flexion gap.

2) The proximal tibia cut only effects the extension gap.

5) The posterior femoral condyle cut effects the flexion and extension gaps.

4) The distal femoral cut only effects the flexion gap.

 

These are important concepts when balancing the knee following total knee replacement.

 

The distal femoral cut only effects the extension gap.

 

 

The proximal tibia cut effects the flexion and extension gaps. The posterior femoral condyle cut effects the flexion only.

 

Attention to these principles is very important to prevent both contractures and flexion instability. Correct Answer: The distal femoral cut only effects the extension gap.

 

1. (2435) Q1-2896:

   While performing revision total knee arthroplasty, the surgeon notices a flexion gap that is larger than the extension gap. The following statement is most likely true:

    

   1) The femoral component is probably too large.

   3) There is inadequate distal femoral augmentation.

   2) There is posterior translation of the femoral component.

   5) There is excessive thickness of the distal femoral augmentation blocks.

   4) There is excessive thickness of the patellar component.

    

    

   Flexion instability is common following revision total knee replacement. The following principles are important: Undersizing the femoral component is common. This occurs secondary to the posterior femoral condyle bone loss.

    

   Anterior translation of the femoral component increases the flexion gap. The use of posterior femoral condyle augments or an offset stem can solve this problem.

    

   Distal femoral augments that are too thick will narrow the extension gap. One should set the joint line approximately 25 mm to 30 mm below the epicondylar axis.

    

   Excessive size of the patellar component will restrict knee flexion, however, it will not change the flexion and extension gaps. Correct Answer: There is excessive thickness of the distal femoral augmentation blocks.

    

2. (2436) Q1-2897:

The stem associated with the highest incidence of osteolysis is the:

 

1) Proximal coated femoral stem

3) Fully coated femoral stem

2) Distal coated femoral stem

5) Cemented femoral stem

4) Patch-porous coated femoral stem

 

The noncircumferentially coated titanium alloy patch-porous coated straight Harris-Galante stem was associated with significant osteolysis, thigh pain, subsidence, and endosteal erosion. The patched porous coating is believed to allow ingress of joint fluid and wear debris into the endosteal canal, increasing the effective joint space.Correct Answer: Patch-porous coated femoral stem

 

During controlled perforation for removal of stem and prosthesis, when making 9-mm holes in the femoral diaphysis:

 

1) The size of the hole should be 20% of the diameter of the shaft

3) The size of the hole should be 60% of the diameter of the shaft

2) The size of the hole must not exceed 30% of the diameter of the shaft

5) The holes must be in the posterolateral surface of the femur

4) Two holes must be one hole diameter apart

 

The size of the hole must not exceed 30% of the diameter of the shaft. Holes should not be placed any closer than two hole diameters apart, and they should be located in the anterolateral surface of the femur to decrease the stress riser.Correct Answer: The size of the hole must not exceed 30% of the diameter of the shaft

 

 

1. (2438) Q1-2899:

   The gold standard for the diagnosis of avascular necrosis of the femoral head is:

    

   1) Bone scan

   3) Magnetic resonance image

   2) Routine roentgenogram

   5) Elevated sedimentation rate

   4) Segmented bone collapse

    

   The gold standard for the diagnosis of avascular necrosis is magnetic resonance imaging. Changes can be seen earliest with this technique before there are changes on routine roentgenogram and even before a patient is symptomatic.Correct Answer: Magnetic resonance image

    

    

2. (2439) Q1-2900:

   The low incidence of infection in ceramic-ceramic total hip replacement is:

    

   1) True only in early infection

   3) Has not been reported in the literature and is only anecdotal

   2) True only in late infection

   5) True because bacteria adhere more strongly to polyethylene

   4) True because bacteria adhere more strongly to ceramic

    

   There is a lower incidence of infection reported in ceramic-ceramic total hip replacements by the Swedish Hip Registry. This may be related to the fact that bacteria typically adhere more strongly to polyethylene than cement, suggesting that both early and late infection may be lower for alumina than polyethylene total hip replacement.Correct Answer: True because bacteria adhere more strongly to polyethylene

    

    

3. (2440) Q1-2901:

The first step in the development of hip osteoarthritis is:

 

1) Abnormal glycosaminoglycans

3) Abnormal weight gain

2) Formation of ganglions

5) Abnormal mechanical stress

4) Fatiguing of labrum under normal stress

 

The first step toward osteoarthritis of the dysplastic hip is fatiguing of the labrum under normal stress. Klaue et al described the different pathomorphologies from a torn labrum to ganglion formation, which has been attributed to acetabular rim syndrome.Correct Answer: Fatiguing of labrum under normal stress

 

The common iliac artery gives rise to all of the following vessels except:

 

1) The external iliac artery

3) The superior gluteal artery

2) The internal iliac artery

5) The internal hypogastric artery

4) The common femoral artery

 

The common iliac artery divides at the L5-S1 vertebral disk. The anterior division, the external iliac artery, continues distally to become the common femoral artery, whereas the posterior division becomes the internal iliac artery. The internal iliac artery branches again into a posterior division, which gives rise to the superior gluteal artery, and an anterior division, which gives off the obturator artery before dividing into the inferior gluteal artery and internal pudendal artery.Correct Answer: The internal hypogastric artery

 

 

1. (2463) Q1-2928:

   The structure at highest risk for injury in total hip arthroplasty (THA) is the:

    

   1) Femoral artery

   3) External iliac artery

   2) Femoral vein

   5) Obturator artery

   4) Inferior gluteal artery

    

   The external iliac artery and vein are immobile and lie close to the pelvis, and thus are at high risk for injury in THA. The external iliac vein lies within 7 mm of the anterior column of the pelvis at the anterior inferior iliac spine and within 4 mm at the acetabula dome. The external iliac artery is at less risk due to its thicker intima and increased distance from the bone. The external iliac artery lies within 10 mm of the bone at the anterior inferior iliac spine and within 7 mm at the acetabular dome. The common femoral artery lies anterior and medial to the hip capsule. Only the iliopsoas lies between the vessel and capsule at this point. The femoral vein lies medial to the artery and is not likely to be injured. The obturator vessels are also at risk, lying fixed within 1 mm of the bony surface at the quadrilateral surface, with their only protection being the interposition of the obturator internus muscle.Correct Answer: External iliac artery

    

    

    

2. (2464) Q1-2929:

The nerve most commonly injured during total hip arthroplasty (THA) is the:

 

1) Superior gluteal nerve

3) Femoral nerve

2) Obturator nerve

5) Peroneal component of sciatic nerve

4) Inferior gluteal nerve

 

The primary nerves of the region are the sciatic, femoral, inferior and superior gluteal, and obturator. The most common nerve injury during THA is to the peroneal division of the sciatic nerve, followed by superior gluteal, obturator, and femoral nerves.

Injury to these structures can lead to loss of function and poor outcomes.Correct Answer: Peroneal component of sciatic nerve

 

Which two quadrants of the acetabulum are most at risk for injury by screws during fixation of total hip arthroplasty (THA):

 

1) Anterior-superior and posterior-inferior

3) Anterior-superior and posterior-superior

2) Posterior-superior and posterior inferior

5) Anterior-superior and anterior-inferior

4) Anterior-inferior and posterior-superior

 

The acetabular quadrant system described by Wasielewski and colleagues is useful for determining the location of planned acetabular screw fixation in THA to avoid neurovascular complications. The quadrants are formed by drawing a line from the anterior-superior iliac spine through the center of the acetabulum and bisecting that line at the center of the acetabulum to form four equal quadrants. The line from the anterior-superior iliac spine to the center of the acetabulum serves as the dividing line between anterior and posterior, and the bisecting line as the division between superior and inferior.

 

In cadaver studies, the posterior-superior and posterior-inferior quadrants were shown to have the thickest bone and best potential for obtaining secure fixation with the least risk for injury to vessels. The anterior-superior quadrant (the quadrant of death) and the anterior-inferior quadrant were shown to be the most dangerous quadrants for fixation due to the thin bone and close proximity of the vessels to bone in that region.Correct Answer: Anterior-superior and anterior-inferior

 

 

1. (2466) Q1-2931:

   What is the most commonly used surgical approach to the acetabulum:

    

   1) Posterior

   3) Anterior

   2) Ilioinguinal

   5) Anterolateral

   4) Medial

    

   The posterior approach to the acetabulum is the least technically demanding approach for total hip arthroplasty (THA) and offers good visualization of the acetabulum, especially of the posterior wall. The posterior approach is the most commonly used approach for THA in the United States. Patients are placed in the lateral position. The approach involves splitting of the gluteus maximus in line with its fibers and no internervous plane is present. The sciatic nerve is protected by the short external rotators after they are detached from their insertions on the femur and reflected medially.Correct Answer: Posterior

    

    

2. (2467) Q1-2932:

   In the ilioinguinal approach, what does the first window allow access to:

    

   1) Pelvic brim and superior pubic ramus

   3) Inferior pubic ramus and sciatic notch

   2) Quadrilateral plate and retropubic space

   5) Anterior sacroiliac joint, internal iliac fossa, and upper anterior column

   4) Ilioschial tuberosity and retropubic space

    

   The ilioinguinal approach provides improved visualization of the pelvic inner surface and anterior column and medial wall of the acetabulum. The patient is placed supine or in a lazy lateral decubitus position. The principle of this approach is to dissect closely along the inner wall of the pelvis and lift each muscular and neurovascular structure off of the bone. Three windows are present in this approach, each providing access to different structures. The first window allows access to the anterior sacroiliac joint, internal iliac fossa, and upper anterior column.Correct Answer: Anterior sacroiliac joint, internal iliac fossa, and upper anterior column

    

    

3. (2468) Q1-2933:

   The most sensitive method for identifying and quantifying the extent of osteolysis is:

    

   1) Plain radiographs

   3) Technetium-99m bone scanning

   2) Magnetic resonance imaging

   5) Helical computed tomography

   4) Computed tomography

    

   If extensive osteolysis is suspected, computed tomography is recommended because plain radiographs underestimate the extent of lysis. Helical computed tomography with metal artifact minimization is the most sensitive method for identifying and quantifying the extent of lysis.Correct Answer: Helical computed tomography

    

4. (2469) Q1-2934:

   The most common cause of vascular injury during total hip arthroplasty (THA) is:

    

   1) Laceration

   3) Arteriovenous fistula

   2) Pseudoaneurysm

   5) Thromboembolic phenomena

   4) True aneurysm

    

   A previous review of vascular injuries sustained during THA revealed the most common etiology of vascular injury as thromboembolic phenomena, followed by laceration, pseudoaneurysm, and arteriovenous fistula.Correct Answer: Thromboembolic phenomena

    

    

5. (2470) Q1-2935:

   The most common cause of damage to femoral vessels is:

    

   1. Extruded cement

      3) Capsule dissection

      2) Migration of the acetabular cup

      5) Screw placement

      4) Aberrant retractor placement

       

      Damage to the femoral vessels is most commonly due to aberrant retractor placement. Care should be taken to ensure that the retractor tip is placed directly on bone, and that the iliopsoas is not interposed between the retractor tip and bone. Extruded cement, acetabular cup migration, and capsule dissection have also been implicated in damage to the femoral vessels.Correct Answer: Aberrant retractor placement

       

       

6. (2471) Q1-2936:

The risk of nerve injury following revision total hip arthroplasty (THA) is approximately:

 

1) 0.5%

1. 1% to 10%

1. 1%

   5) More than 20%

   4) 10% to 20%

    

   Following primary THA, the incidence of nerve palsy is reported to be approximately 1.3%, but may be as high as 5.2% for primary THA performed for developmental dysplasia or dislocation. For revision surgery, the incidence may be as high as 7.6%.Correct Answer: 1% to 10%

    

    

    

    

    

   Slide 1

   The most likely underlying diagnosis in this patient is:

    

   1) Gout

   3) Heterotopic ossification

   2) Rheumatoid arthritis

   5) Synovial chondromatosis

   4) Pigmented villonodular synovitis

    

   This radiograph presents a Brooker class IV heterotopic ossification in a 79-year-old woman after revision of a monopolar hemiarthroplasty to a press-fit, porous-coated acetabular component and a cemented femoral stem. The patient sustained a cerebrovascular accident 12 weeks before surgery. She had no other risk factors for heterotopic ossification formation after total hip arthroplasty. Other risk factors for heterotopic ossification include previous surgery, men with hypertrophic osteoarthritis, traumatic brain injury, spinal hyperostosis, and posttraumatic arthritis.Correct Answer: Heterotopic ossification

    

    

   330. (2473) Q1-2938:

    

    

    

   Slide 1

   This radiograph is most typical of:

    

   1) Stress fracture

   3) Osteitis pubis

   2) Osteocarcinoma

   5) Ewing's sarcoma

   4) Osteomyelitis of the pubic symphysis

    

   Osteomyelitis of the pubic symphysis is a rare condition, accounting for less than 1% of all acute hematogenous osteomyelitis cases. The condition is well described in elderly patients following urologic, gynecologic, and pelvic procedures. Osteomyelitis of the pubic symphysis has also been reported in intravenous drug abusers, after cardiac catheterization, and can occur spontaneously in athletes and children.Correct Answer: Osteomyelitis of the pubic symphysis

    

   Which of the following symptoms is least common in patients with osteomyelitis of the pubis:

    

   1) Distal anterior pelvic pain

   3) Rectus muscle spasm

   2) Adductor muscle spasm

   5) Wide-based waddling gait

   4) Abductor muscle spasm

    

   Osteomyelitis of the pubic symphysis is a rare condition, occurring in 2% to 11% of all patients with osteomyelitis of the pelvis. The osteitis pubis is the least affected area. Signs and symptoms of osteomyelitis of the pubic symphysis include distal anterior pelvic pain, adductor and rectus muscle spasms, and a wide-based waddling gait. Fever, leukocytosis, elevated erythrocyte sedimentation rate, and positive blood cultures may also be present. Unilateral rarefaction and sclerosis with cystic changes may be seen on radiographs 10 to 14 days after symptoms begin. Radionucleotide scans, computed tomography, and magnetic resonance imaging may aid in the diagnosis.Correct Answer: Abductor muscle spasm

    

    

    

   1. (2475) Q1-2940:

      Common risk factors associated with extensor mechanism disruption after total knee arthroplasty (TKA) include all of the following except:

       

      1) Limited preoperative range of motion

      3) Medial parapateller exposure

      2) Difficult surgical exposure

      5) Obesity

      4) Disruption of vascular supply to the patella

       

      The etiology of extensor mechanism disruption after TKA is unknown. Researchers suggest that disruption of the vascular supply to the patella and patellar mechanism during the exposure may cause weakening of the patella and extensor mechanism. In addition, the frequency of extensor mechanism disruption has been reportedly increased in patients who have a preoperative limited range of motion or difficult surgical exposure.Correct Answer: Medial parapateller exposure

       

       

   2. (2476) Q1-2941:

      Contributing factors causing female athletes to have more anterior cruciate ligament injuries than men include all of the following except:

       

      1) Intercondylar notch width

      3) Increased quadriceps angle

      2) Ligament size

      5) Fitness level

      4) Strong overactive hamstrings

       

      Female athletes are two to eight times more likely than men to sustain an anterior cruciate ligament injury when playing sports such as soccer, basketball, and volleyball. The exact etiology of gender-based injuries is unclear. Various intrinsic factors (intercondylar notch width, ligament size, quadriceps angle, joint laxity, hormonal effects) and extrinsic factors (muscular strength/weakness, fitness level, hamstring:quadriceps ratio) have been proposed as contributing factors. A strong hamstring actually protects the anterior cruciate ligament and is a preventative measure.Correct Answer: Strong overactive hamstrings

       

       

   3. (2477) Q1-2942:

   The best results of hip fracture repair occur:

    

   1) In the first 6 hours

   3) Within the second day

   2) Within the first day

   5) Three days after repair

   4) Within the third day

    

   Medical consequences of time issues relevant to hip fractures have been examined by several authors. Operation within the first day of injury is superior and provides better results than delaying the procedure. However, the economic consequences of such a delay have not been examined.Correct Answer: Within the first day

    

    

    

    

    

   Slide 1

   This T2-weighted sagittal magnetic resonance image of a right knee reveals:

    

   1) Avascular necrosis of the distal femur

   3) Anterior cruciate ligament rupture

   2) Synovial sarcoma

   5) Popliteal cyst

   4) Posterior cruciate ligament rupture

    

   Baker's or popliteal cyst, described first by Adams and later by Baker, is a distended bursa originating posterior to the medial head of the gastrocnemius muscle or semimembranous tendon and generally presents with posterior knee pain and a palpable mass. This case is unusual in that the dissection was proximal, unlike the typical distal progression of the popliteal cyst.Correct Answer: Popliteal cyst

    

    

   1. (2479) Q1-2944:

      What is the main characteristic shift in the outcome assessment of total hip arthroplasty (THA) in the past decade:

       

      1) Description of more technical details

      3) Introduction of more hip prosthesis designs

      2) Analysis and measurement of the impact and longevity of the procedure on a patient's quality-of-life

      5) Decreasing number of dislocations

      4) Introduction of new functional scoring systems

       

      Over the past two decades, a continuous shift toward outcome assessment in medicine has occurred. Publications previously devoted to technical details and surgical technique have started analyzing and measuring the impact and longevity of medical procedures on patients' quality-of-life and have compared the cost-effectiveness of different procedures.Correct Answer: Analysis and measurement of the impact and longevity of the procedure on a patient's quality-of-life

       

       

   2. (2480) Q1-2945:

   In the study design for evaluating the effectiveness of total hip replacement, the endpoint can be only:

    

   1) Revision hip surgery

   3) Any well-defined chosen point, such as revision hip surgery or functional level and pain

   2) Radiographic loosening of the implant

   5) Range of motion

   4) Pain or functional level

    

   In the study design, it is paramount that a universal, well-defined endpoint is chosen. In the well-established Scandinavian Hip Registries, this endpoint is revision total hip arthroplasty. Whether this endpoint is sensitive enough is debatable. For more in-depth studies, several other endpoints, such as pain or postoperative functional level, may also be used.Correct Answer: Any well-defined chosen point, such as revision hip surgery or functional level and pain

    

   The single most important criterion to identify the type of hip implant for future analysis in a hip arthroplasty register is:

    

   1) The name of the manufacturer and the year of implant production

   3) The implant's catalogue number provided by the manufacturer

   2) The name of the implant and the year of implant production

   5) The surgeon's name and implant manufacturer

   4) The name of the manufacturer and implant

    

   For the implanted prosthesis, manufacturer, name, material, and catalogue numbers are essential for precise future identification. The role of the catalogue numbers cannot be underestimated as successive generations of implants were put on the market with the same brand name (eg, Charnley hip). Without recording the catalogue numbers, it is impossible to determine what generation of implant is being compared to another.Correct Answer: The implant's catalogue number provided by the manufacturer

    

    

   1. (2482) Q1-2947:

      The main advantage of multicenter studies in analyzing total hip arthroplasty is:

       

      1) The inclusion of different surgeons

      3) The ability to obtain a large number of patients

      2) The inclusion of different countries

      5) Giving more accurate data

      4) The inclusion of different hip implants

       

      The main advantage of multicenter studies - although they are time-consuming, expensive, and often frustrating - is obtaining large numbers of patients in a relatively short time. This is important when examining statistical differences between varying results.Correct Answer: The ability to obtain a large number of patients

       

       

   2. (2483) Q1-2950:

      When comparing viral vectors with nonviral vectors for gene delivery, the advantages of nonviral vectors include all of the following except:

       

      1) Safety

      3) More efficiency

      2) Less immunogenicity

      5) Special packaging cell lines

      4) Easier production

       

      Because of the safety concerns, immunogenicity issues, and production complications associated with viral vectors, nonviral delivery systems were developed by complexing of genes (DNA) to various chemical formulations. Nonviral delivery systems stabilize DNA and increase its uptake and include plasmids, peptides, cationic liposomes, DNA-ligand complexes (recognize specific cell-surface receptors, leading to receptor-mediated uptake), and gene gun (particles of gold coated with DNA, forced into the cells with high velocity bombardment). However, nonviral vector efficiency is lower than viral vectors.Correct Answer: More efficiency

       

       

       

   3. (2484) Q1-2951:

   All of the following have been used as viral vectors for gene delivery except:

    

   1) Adeno-associated virus

   3) Herpes simplex virus

   2) Rotavirus

   5) Retroviral vector

   4) Lentivirus

    

   A retroviral vector derived from the Moloney murine leukemia retrovirus is among the best-developed viral vectors. Other viral vectors include adenovirus, adeno-associated virus, and herpes simplex virus. Novel vector systems based on lentivirus, which is a type of retrovirus that includes human immunodeficiency virus, are being developed.Correct Answer: Rotavirus

    

   The principle of homologous recombination in gene therapy is used to:

    

   1) Replace a defective gene by a wild-type gene

   3) Supplement a wild-type gene

   2) Suppress the expression of a mutant gene

   5) Replace a defective gene by a normal gene

   4) Alter the expression of a mutant gene

    

   Novel approaches to treating genetic diseases involve gene repair or replacement rather than gene supplementation. One such approach is based on the principle of homologous recombination (replacement of a defective gene by a normal gene).Correct Answer: Replace a defective gene by a normal gene

    

    

   1. (2486) Q1-2953:

      The virus associated with the most immune reactions is:

       

      1) Adeno-associated virus

      3) Adenovirus

      2) Gutted adenovirus

      5) Herpes simplex virus

      4) Retrovirus

       

      Adenoviral vectors can cause inflammatory reaction due to immune activation, an event linked to the first death related to gene therapy. This occurred in September 1999 at the University of Pennsylvania in a clinical trial in which an 18-year-old patient received infusion of more than a trillion adenoviral vectors directed to his liver, which triggered a systemic inflammatory response that became uncontrollable, leading to organ failure and death. Newer-generation gutted or gutless adenovirus vectors are nonimmunogenic.Correct Answer: Adenovirus

       

       

   2. (2487) Q1-2954:

      Compared with the ex vivo gene delivery system, the in vivo system is:

       

      1) Technically complex

      3) Safer

      2) Target specific

      5) More invasive

      4) Less invasive

       

      Two basic strategies exist for gene delivery. Direct, or in vivo, gene therapy involves direct introduction of vectors into the body. Indirect, or ex vivo, gene therapy involves removal of target cells from the body, vector introduction by incubation of the cells in vitro, and reimplantation. The in vivo system is less invasive.Correct Answer: Less invasive

       

       

   3. (2488) Q1-2955:

   The gene that has been studied in greatest detail for application in osteoarthritis is:

    

   1) p53

   3) Tissue inhibitors of metalloproteinases-4

   2) Interleukin (IL)-13

   5) Bone morphogenetic protein-2

   4) IL-1 receptor antagonist

    

   Gene therapy has been suggested as a means of delivering sustained therapeutic levels of anti-arthritis gene products to diseased joints. Local gene delivery to the synovial tissue is the approach of choice for osteoarthritis and other conditions affecting a few joints. Gene therapy is less suited to address the extra-articular components of systemic conditions, such as rheumatoid arthritis.

    

    

   The gene that has been studied in greatest detail encodes the human IL-1 receptor antagonist. Correct Answer: IL-1 receptor antagonist

   The osteoinductive potential of LIM mineralization protein (LMP)-1 gene has been studied for clinical application in:

    

   1) Fracture repair

   3) Cartilage regeneration

   2) Spinal fusion

   5) Meniscal injury

   4) Ligament healing

    

   Identification of LMP-1, a novel intracellular protein, is a step forward in osteoinductive proteins. Unlike bone morphogenetic protein, which is a secreted protein that binds to cell-surface receptor to initiate a response, LMP-1 is an intracellular signaling molecule. Boden and colleagues transfected bone marrow cells from rats ex vivo with LMP-1 gene using DNA plasmid vector and used them during posterior thoracic and lumbar spinal fusion in rats.Correct Answer: Spinal fusion

    

    

   1. (2490) Q1-2957:

      The gene studied for application in osteoporosis and wear-induced osteolysis is:

       

      1) Osteoprotegerin

      3) Transforming growth factor-Ã1

      2) Bone morphogenetic protein

      5) Interleukin (IL)-receptor antagonist

      4) LIM mineralization protein

       

      Various cytokines and cytokine antagonists hold promise as new therapeutic agents for osteoporosis. Baltzer and colleagues showed that intramedullary injection of Ad-IL-1Ra gene in a murine ovariectomy model strongly reduced the loss of bone mass. Using a similar model, Bolon and associates studied the effect of adenovirus-mediated transfer of osteoprotegerin, which showed more bone volume with reduced osteoclast numbers in axial and appendicular bones after 4 weeks compared with sham-operated mice.Correct Answer: Osteoprotegerin

       

       

   2. (2491) Q1-2958:

      Gene transfer to a cell using viral vectors is called:

       

      1) Transduction

      3) Transformation

      2) Transfection

      5) Augmentation

      4) Conjugation

       

      In vivo gene delivery involves the direct injection of vectors containing the genes into the body with the expectation that they will reach and transduce the target cell. Ex vivo gene delivery is a process whereby the target cells are removed from the body, genetically altered in vitro, and reimplanted into the body.Correct Answer: Transduction

       

       

   3. (2492) Q1-2959:

   Which of the following genes has been shown to stimulate proteoglycan synthesis for prevention of disk degeneration:

    

   1) LIM mineralization protein

   3) Decorin

   2) Bone morphogenetic protein-7

   5) Osteoprotegerin

   4) Transforming growth factor (TGF)-Ã1

    

   Intervertebral disk degeneration has been associated with a progressive decrease in proteoglycan content of nucleus pulposus. The potential application of gene therapy for prevention of disk degeneration is to increase or maintain the proteoglycan content of nucleus pulposus. Thompson and colleagues reported that addition of TGF-Ã1 to canine disk tissue in culture stimulated in vitro proteoglycan synthesis.Correct Answer: Transforming growth factor (TGF)-Ã1

    

   The advantages of an arthroscopic-assisted rotator cuff repair include all of the following except:

    

   1) The surgeon can approach the shoulder from multiple angles.

   3) Operative time is shorter.

   2) The deltoid attachment is preserved.

   5) As opposed to other repair methods, a better early range of motion is achieved.

   4) Postoperative rehabilitation is accelerated.

    

   Arthroscopy facilitates a thorough assessment and treatment of a rotator cuff tear by approaching the shoulder from multiple angles. It preserves the deltoid attachment to the acromion and postoperative rehabilitation is potentially accelerated if the deltoid does not need to be protected. Arthroscopy achieves a better early range of motion than other repair methods; however, it requires a longer operative time.Correct Answer: Operative time is shorter.

    

    

   1. (4054) Q1-3025:

      The disadvantages of a complete arthroscopic repair of a rotator cuff include all of the following except:

       

      1) Complete arthroscopic repair limits some suture configuration options in the tendon.

      3) Complete arthroscopic repair is technically difficult to perform.

      2) Postoperative pain is increased.

      5) Operative time is longer.

      4) Complex instrumentation is required.

       

      Arthroscopic repair techniques generally require the use of suture anchors and limit some suture configuration options in the tendon. Complete arthroscopic repair is technically difficult, requires significantly greater and more complex instrumentation, and has a potentially longer operative time. However, it decreases postoperative pain.Correct Answer: Postoperative pain is increased.

       

       

   2. (2553) Q1-3026:

      The types of rotator cuff tear patterns are:

       

      1) Crescent-shaped and massive contracted immobile tears

      3) Vertical and horizontal cleavage tears

      2) U-shaped and L-shaped tears

      5) Vertical cleavage, U-shaped, and L-shaped tears

      4) Crescent-shaped, U-shaped, L-shaped, and massive contracted immobile tears

       

      Four major types of rotator cuff tear patterns have been described and are based on the shape and mobility of the tear margins: crescent-shaped, U-shaped, L-shaped, and massive contracted immobile tears. Vertical and horizontal cleavage tears are related to meniscal tears in the knee.Correct Answer: Crescent-shaped, U-shaped, L-shaped, and massive contracted immobile tears

       

       

   3. (2554) Q1-3027:

   Which of the following rotator cuff tears is the simplest to repair:

    

   1) U-shaped tear

   3) Crescent-shaped tear

   2) L-shaped tear

   5) Parrot-beak tear

   4) Vertical cleavage tear

    

   Crescent-shaped tears are the simplest of all tears to repair and demonstrate minimal retraction and excellent mobility. They can be repaired directly to the bone with minimal tension. The anchors are placed percutaneously using a spinal needle. Suture passing techniques are then used and the rotator cuff is tied down. Vertical cleavage and parrot-beak tears refer to meniscal injuries in the knee.Correct Answer: Crescent-shaped tear

    

    

    

    

    

   Slide 1

   The following image depicts:

    

   1) An arthroscopic view of a massive rotator cuff tear

   3) An arthroscopic view of a U-shaped rotator cuff tear

   2) An arthroscopic view of an L-shaped rotator cuff tear

   5) An arthroscopic view of a medial meniscus tear of the knee

   4) An arthroscopic view of a crescent-shaped rotator cuff tear

    

   The image depicts a lateral arthroscopic view of a crescent-shaped tear, which demonstrates minimal retraction and excellent mobility, and is easily repaired.Correct Answer: An arthroscopic view of a crescent-shaped rotator cuff tear

    

    

   1. (2556) Q1-3029:

       

       

       

      Slide 1

      The following image depicts:

       

      1) A lateral arthroscopic view of a massive U-shaped tear of the rotator cuff

      3) A lateral arthroscopic view of an L-shaped tear of the rotator cuff

      2) A lateral arthroscopic view of a crescent-shaped tear of the rotator cuff

      5) A bucket-handle tear of the medical meniscus

      4) A degenerative posterior horn tear of the medial meniscus

       

      The image depicts a lateral arthroscopic view of a massive U-shaped tear. U-shaped rotator cuff tears extend much farther medially than crescent-shaped tears, with the apex of the tear adjacent to or medial to the glenoid rim.Correct Answer: A lateral arthroscopic view of a massive U-shaped tear of the rotator cuff

       

       

   2. (2557) Q1-3030:

   All of the following are static restraints providing stability for the shoulder except:

    

   1) Labrum

   3) Glenohumeral ligaments

   2) Glenoid

   5) Joint capsule

   4) Rotator cuff and scapular muscles

    

   The shoulder allows more range of motion than any other joint in the body and is susceptible to injury. It has both static and dynamic restraints. The rotator cuff and scapular muscles are the dynamic restraints. The glenoid, labrum, glenohumeral ligaments, and joint capsule are the static restraints.Correct Answer: Rotator cuff and scapular muscles

    

   Which of the following provides the greatest restraint to anterior dislocation of the shoulder:

    

   1. Superior glenohumeral ligament

      3) Infraspinatus

      2) Supraspinatus

      5) Joint capsule

      4) Inferior glenohumeral ligament

       

      The inferior glenohumeral ligament provides the greatest restraint to dislocation of the shoulder. The inferior glenohumeral ligament is under the most stress at 90° of abduction with external rotation and extension. Bracing to restrict this position benefits a patient with instability.Correct Answer: Inferior glenohumeral ligament

       

       

      1. (2559) Q1-3032:

         The percentage of patients 20 to 40 years of age who have recurrent shoulder instability is:

          

         1) 10%

         3) 40%

         2) 20%

         5) 60%

         4) 50%

          

         Suffering from recurrent instability in the shoulder joint depends on a patientâs age and activity level. Ninety percent of patients younger than 20 years of age have recurrent instability. In patients 20 to 40 years of age, 40% have recurrent instability.Correct Answer: 40%

          

          

      2. (2560) Q1-3033:

         The percentage of athletes with recurrent instability choosing to return to collision sports after an anterior shoulder dislocation is:

          

         1) 20%

2. 60%

1. 40%

   5) 100%

   4) 80%

    

   A patientâs activity level is the predicting factor for recurrent instability. Eighty-two percent of athletes suffer from recurrent instability compared with 30% of nonathletes. The percentage approaches 100% for athletes choosing to return to collision sports.Correct Answer: 100%

    

    

   1. (2561) Q1-3034:

   The most frequently transplanted human tissue is:

    

   1. Bone

2. Kidney

1. Blood

   5) Skin

   4) Cornea

    

   After blood, bone is the most frequently transplanted human tissue. However, bone autografting may eventually become a thing of the past. Bone replacement with synthetic materials and growth factors is becoming common procedure in the orthopedic operating room.Correct Answer: Blood

    

   The first documented bone transplant was performed by:

    

   1) Van Meekeren

   3) Phemister

   2) Macewan

   5) Albee

   4) Ferguson

    

   The first documented bone transplant was performed in 1668 by Dutch surgeon Job van Meekeren, when he used a dog cranium (a xenograft) to repair a soldierâs skull defect. Scottish surgeon William Macewan performed the first bone allograft in 1880 when he replaced the infected humerus of a 4-year-old boy with a tibia graft taken from a child with rickets. In his 1914 publication, Phemister noted the importance of âhemostasis, asepsis, and coaptation of partsâ in successful bone grafting. Phemister and Albee elucidated the important factors in bone grafting in the early 20th century, paving the way for the recent work that has delineated the importance of osteoconductive scaffolding, osteoinductive growth factors, and osteogenic progenitor stem cells in bone graft healing.Correct Answer: Van Meekeren

    

    

    

   1. (2563) Q1-3036:

      In most clinical applications, a bone autograft is preferable to a bone allograft because:

       

      1) A bone autograft is more osteoconductive, osteoinductive, and osteogenic than a bone allograft.

      3) A bone autograft incorporates more slowly than a bone allograft.

      2) A bone autograft has a higher risk of infection than a bone allograft.

      5) There are more immunological considerations.

      4) Bone autografts are in limitless supply.

       

      Autografting is the standard method used to replace bone loss due to trauma, infection, tumor resection, revision arthroplasty, and arthrodesis. Rapid incorporation and consolidation with the lack of immunological considerations make bone harvested from the patient ideal. Bone autografts are osteoconductive and contain osteoinductive proteins and cells, which are able to give rise to bone-forming cells. Because of its lower risks, a bone autograft (especially of cancellous bone) is preferable to a bone allograft. Bone autografts, however, are in limited supply, particularly in children.Correct Answer: A bone autograft is more osteoconductive, osteoinductive, and osteogenic than a bone allograft.

       

       

   2. (2564) Q1-3037:

      When nonvascularized cortical allografts lose mechanical strength during the first year following surgery, it is most likely due to:

       

      1. Revascularization

         3) Infection

         2) Failure of the graft to incorporate

         5) Failure to provide initial structural support

         4) Complex regional pain syndrome

          

         Nonvascularized cortical grafts may provide immediate structural support but lose mechanical strength over the first few months. Loss of mechanical strength is due to the revascularization process, which causes osteoporosis and subsequent graft weakening. The process requires resorption of at least some graft bone to allow ingrowth of blood vessels and takes a significantly longer period of time in cortical bone than in cancellous bone.Correct Answer: Revascularization

          

          

   3. (2565) Q1-3038:

   What percentage of osetocytes present in a vascularized cortical autograft survive:

    

   1) 24%

2. 60%

1. 40%

   5) 90%

   4) 80%

    

   Vascularized cortical autografts are effective structural grafts that heal quickly without the revascularization process and consequent mechanical compromise found in avascular cortical autografts and allografts. Typically, more than 90% of osteocytes present in a vascularized cortical allograft survive transplantation and bring their own blood supply, perhaps making the contribution of the recipient bed tissues less important than healing.Correct Answer: 90%

    

   Vascularized free fibular grafts have been used to treat all of the following except:

    

   1. Congenital pseudoarthrosis of the tibia

2. Osteonecrosis of the femoral head

1. Tumor-related defects in the proximal humerus

5) Nonunions of the femur

4) Pseudoarthrosis of the scaphoid

 

Vascularized free fibula grafts have been used in numerous locations for a variety of difficult problems. Potential situations in which a patient might benefit from vascularized autografts include osteonecrosis of the femoral head, reconstruction of tumor-related defects in the proximal humerus and lower extremity, treatment of congenital tibial pseudoarthrosis, and nonunions of the femur, tibia, and femoral neck.Correct Answer: Pseudoarthrosis of the scaphoid

 

 

1. (2567) Q1-3040:

   Demineralized bone matrix is:

    

   1) Osteogenic

   3) Osteoinductive, osteogenic, and osteoconductive

   2) Osteogenic and osteoconductive

   5) Only osteoconductive

   4) Osteoconductive and osteoinductive

    

   Demineralized bone matrix is recognized as having a variable amount of osteoinductive capacity and some osteoconductive properties. The biologic activity varies with specific processing and storage methods, in addition to variation among donors.Correct Answer: Osteoconductive and osteoinductive

    

    

2. (2568) Q1-3041:

Which of the following has the highest risk of disease transmission:

 

1) Cortical allograft

3) Cancellous allograft

2) Cortical autograft

5) Cortical allograft and cancellous allograft have the same risk of disease transmission.

4) Cancellous autograft

 

Cortical bone is of greater density than cancellous bone, and it is believed that the density accounts for the slightly higher risk of disease transmission, as pathogens are less easily destroyed when embedded in a more dense tissue bed. Two cases of HIV transmission resulting from cortical allografts have been reported.Correct Answer: Cortical allograft

 

 

 

 

 

Slide 1 Slide 2

The following image (Slide 1) depicts:

 

1) The removal of congenital pseudoarthrosis of the tibia

3) A fibular autograft

2) A vascularized iliac autograft

5) A fibular autograft for spinal fusion

4) The harvesting of the vascularized fibula from the contralateral leg

 

The image depicts the harvesting of a vascularized fibula from the contralateral leg, which is then used to move a defect in congenital pseudoarthrosis of the tibia on the opposite side. The following image (Slide 2) shows clinical union 3.5 years later.Correct Answer: The harvesting of the vascularized fibula from the contralateral leg

 

 

1. (2570) Q1-3043:

   Vascularized transplantation of the knee and femoral diaphysis is most frequently complicated by:

    

   1) Immunosuppressive medications

   3) Bony nonunions

   2) Pulmonary emboli

   5) Deep venous thrombosis (DVT)

   4) Acute infections

    

   Hofmann and Kirschner reported their experiences with transplantation of vascularized diaphyseal femora and vascularized knees. While using an immunosuppressive regimen consisting of antithymocyte globulin, cyclosporine, azathioprine, and methylprednisolone, which was tapered over 6 months to cyclosporine monotherapy, three patients underwent transplantation of vascularized femoral diaphysis and five patients underwent transplantation of the entire knee, including the extensor mechanism and joint capsule. According to their most recent report, four of these eight patients (two from each group) are currently weight bearing on their transplants. As the authors state, these vascularized bone transplants were âfraught with complications,â largely related to the immunosuppressive medications.Correct Answer: Immunosuppressive medications

    

    

    

2. (2636) Q1-3127:

When treating an infected joint prosthesis with antibiotic cement, the antibiotic elution should stay above the minimum inhibitory concentration (MIC) for a minimum of:

 

1) 1 week

3) 3 weeks

2) 2 weeks

5) 6 weeks

4) 4 weeks

 

Antibiotic elutions differ among brands of cement. However, the antibiotic concentrations should stay above the MIC for at least 3 weeks. The effect is local and there is no significant absorption of a specific antibiotic out of the bone cement and into the plasma.Correct Answer: 3 weeks

 

After implantation, the antibiotic inside bone cement will be present and can be measured for up to:

 

1) 1 day

3) 2 weeks

2) 1 week

5) Several months

4) 3 weeks

 

The antibiotic inside bone cement will be present in the bone cement for months or even years after implantation into a patient. Antibiotic has been measured present even after 5 years.Correct Answer: Several months

 

 

1. (2638) Q1-3129:

   The chances of an arthroplasty revision becoming re-infected by a different organism or the initial infection after a two-stage revision is approximately:

    

   1) 5%

   3) 20%

   2) 10%

   5) 50%

   4) 40%

    

   In one series, 23% of arthroplasty revisions became re-infected by a different organism even after a two-stage revision. However, re-infection is usually, although not always, caused by the same microorganism that caused the initial infection. Once the white blood cell count, sedimentation rate, and C-reactive protein count return to normal, it is usually safe to re-implant the prosthesis.Correct Answer: 20%

    

    

2. (2639) Q1-3130:

 

 

 

Slide 1

Which of the following antibiotics has the highest concentration locally from Palacos-R (Biomet, Warsaw, IN) cement:

 

1) Tobramycin

3) Bacitracin

2) Lincomycin

5) Keflex

4) Gentamicin

 

The Slide represents different antibiotics that may be used with bone cement and the release of antibiotics over a 10-day period. Gentamicin leads the way with a high concentration locally. Bacitracin, for instance, does not leach in high concentrations from Palacos-R bone cement.Correct Answer: Gentamicin

 

The maximum amount of antibiotic powder that can be added as a temporary spacer to 40 g of cement powder is:

 

1) 1 g

3) 4 g

2) 2 g

5) 9 g to 10 g

4) 6 g to 8 g

 

Surgeons should not add more than 6 g to 8 g of antibiotic powder per 40 g of cement powder. One also needs to be careful when adding additional antibiotic powder of the same type, especially to Palacos-R (Biomet, Warsaw, IN) cement, as an overdose may occur. The cement powder should be mixed with the liquid and then the antibiotic powder added to facilitate setting of the cement.Correct Answer: 6 g to 8 g

 

 

1. (2641) Q1-3132:

   The optimal depth of cement penetration for prosthesis insertion is:

    

   1) 1 mm

   3) 3 mm

   2) 2 mm

   5) 8 mm

   4) 4 mm

    

   Pressure magnitude is the most influential of all factors considered in cement penetration behavior. The optimal depth of cement penetration is 4 mm. The higher the pressure is inside the femoral canal, the more effectively the cement will interdigitate.Correct Answer: 4 mm

    

    

2. (2642) Q1-3133:

   Which of the following most effectively provides the strongest fixation when cementing a prosthesis in a femur:

    

   1) A thin cancellous layer

   3) A poor quality cancellous layer

   2) No cancellous layer at all

   5) A straight-stem femoral prosthesis

   4) High-quality, radiodense cancellous bone

    

   The most effective way to provide the strongest fixation when cementing a prosthesis in a femur is to insert it into high-quality, radiodense cancellous bone using a tapered femoral stem, which creates higher intramedullary pressures than a straight stem.Correct Answer: High-quality, radiodense cancellous bone

    

    

3. (2643) Q1-3134:

Which of the following is not a risk factor for fracturing cement around a prosthesis:

 

1) A sharp corner in the metal

3) A thick cement mantle

2) A cement mantle less than 3 mm thick

5) Local debonding of the cement-metal interface

4) Voids or air bubbles in the cement mantle

 

Sharp corners in the metal act as chisels and, as time goes by, are driven into the cement causing cracks. A cement mantle less than 3 mm thick, voids or air bubbles in the cement mantle, and local debonding of the cement-metal interface are also risk factors. A thick cement mantle of 4 mm or greater is desired because a thin mantle cannot sustain the prosthesis.Correct Answer: A thick cement mantle

 

To obtain an adequate cement penetration of 4 mm at a pressure of 0.2 MPA to 0.3 MPA in arthritic bone, one needs to maintain:

 

1) 10 kg of pressure for 20 seconds

3) 30 kg of pressure for 30 seconds

2) 20 kg of pressure for 30 seconds

5) 50 kg of pressure for 50 seconds

4) 40 kg of pressure for 30 seconds

 

To extrapolate the above to the clinical situation, one must maintain a force of 40 kg to 60 kg of pressure for at least a period of 40 to 60 seconds. Adequate penetration of less than 40 kg of pressure for less than 40 seconds does not give adequate cement penetration.Correct Answer: 50 kg of pressure for 50 seconds

 

 

1. (2645) Q1-3136:

   Which of the following commercially available cements has the lowest tensile strength value:

    

   1) Palacos-R (Biomet, Warsaw, IN)

   3) Simplex P (Stryker, Kalamazoo, MI)

   2) Sulfix-60 (Sulzer, Austin, TX)

   5) Zimmer Dough (Zimmer, Warsaw, IN)

   4) CMW3 (Wright Medical Technology, Inc, Arlington, TN)

    

   Zimmer Dough has the lowest value of tensile strength; however, all of the above are FDA-approved cements and of sufficient quality.Correct Answer: Zimmer Dough (Zimmer, Warsaw, IN)

    

    

2. (2646) Q1-3137:

   Which of the following bone cements has demonstrated the lowest cycles to failure:

    

   1) Simplex P (Stryker, Kalamazoo, MI)

   3) Boneloc (Biomet, Warsaw, IN)

   2) Palacos-R (Biomet, Warsaw, IN)

   5) Sulfix-60 (Zimmer, Warsaw, IN)

   4) Zimmer Dough (Zimmer, Warsaw, IN)

    

   Simplex P and Palacos-R display outstanding results when tested in the cyclic conditions. Boneloc demonstrated the lowest cycles to failure.Correct Answer: Boneloc (Biomet, Warsaw, IN)

    

    

3. (2647) Q1-3138:

The most significant factor reducing porosity in bone cement is:

 

1) Storage temperature only

3) Vacuum-mixing medium viscosity

2) Centrifugation of low viscosity cement

5) Vacuum-mixing only

4) A combination of vacuum-mixing and centrifugation

 

The most significant factor reducing porosity in bone cement is a combination of centrifugation and vacuum-mixing. If cement is centrifuged and vacuum-mixed, then low viscosity cement is not significantly different from medium viscosity cement. A comparison of storage temperatures at 4° C and 21° C shows little effect on cement bubbles or cement voids, or porosity of bone cement.Correct Answer: A combination of vacuum-mixing and centrifugation