Orthopedics Hyperguide MCQ 1-50
FREE Orthopedics 2022 MCQ 1-50
1. (208) Q1-315:
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
Correct Answer
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
Correct Answer
3. (210) Q1-318:
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 antibiotiCtherapy
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
Correct Answer
4. (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
Correct Answer
5. (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
Correct Answer
6. (213) Q1-321:
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
Correct Answer
7. (231) Q1-341:
Following acute traumatiCpatellar 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
Correct Answer
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 traumatiCpatellar dislocation, the medial patellofemoral ligament is disrupted
■Correct Answer: Medial patellofemoral ligament
8. (233) Q1-344:
The most common sequelae following traumatiCshoulder 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 traumatiCshoulder 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
9. (524) Q1-726:
A 55-year-old woman has rheumatoid arthritis with shoulder, elbow, and hand/wrist symptoms. No single site of involvement is more symptomatiCthan 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 symptomatiCjoints 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 arthritiCelbow
■Correct Answer: Hand/wrist, shoulder, elbow
10. (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
11. (534) Q1-736:
Posterior translation of the humeral head is associated with which of the following arthritiCetiologies:
1) Primary osteoarthritis
3) Post-infectious arthritis
2) Rheumatoid arthritis
5) Post-traumatiCarthritis
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 statiCposterior subluxation of the humeral head with arthritis
■Correct Answer: Primary osteoarthritis
12. (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
13. (536) Q1-738:
When performing total shoulder arthroplasty, a subscapularis tenotomy is performed as part of the surgical exposure. The following anatomiClandmark 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
14. (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
15. (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
16. (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
17. (540) Q1-742:
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, osteoarthritiCpatients may suffer from the same type of glenoid loosening in the absence of a functioning rotator cuff. EccentriCloading caused by the cuff deficiency can lead to progressive loosening and a "rocking horse glenoid."Correct Answer: Dysfunction of the rotator cuff
18. (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
19. (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 prosthetiCadaptability pioneered by Walch.1
Correct Answer: 40° to 45°
20. (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 arthritiCchanges 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
21. (571) Q1-796:
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-traumatiCarthritis
The slide depicts a type B2 biconcave glenoid as classified by Walch secondary to primary OA.
Correct Answer: Primary osteoarthritis
22. (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
23. (573) Q1-801:
Posterior translation of the humeral head is associated with which of the following arthritiCetiologies:
1) Primary osteoarthritis
3) Post-infectious arthritis
2) Rheumatoid arthritis
5) Post-traumatiCarthritis
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 statiCposterior subluxation of the humeral head with arthritis
■Correct Answer: Primary osteoarthritis
24. (574) Q1-804:
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
25. (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
26. (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
27. (577) Q1-810:
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 narcotiCpain medications
3) Open rotator cuff repair
2) ArthroscopiCrotator 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 eccentriCloading. 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
Figure 1The 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
29. (579) Q1-812:
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 magnetiCresonance 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) ArthroscopiCdebridement of the rotator cuff
5) Unconstrained total shoulder arthroplasty
4) Humeral head arthroplasty
The magnetiCresonance 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 prognostiCindicator for rotator cuff function using computed tomography. These observations were also applied to magnetiCresonance 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 eccentriCloading
■Correct Answer: Unconstrained total shoulder arthroplasty
31. (662) Q1-914:
Figure A Figure B
A 42-year-old male has a history of 6 months of pain in the lower thoraciCregion. Recently, the patient developed weakness in the right lower extremity, bladder and bowel movement. Plain x-rays were normal, but an magnetiCresonance imaging (MRI) showed a posterolateral thoraciCdisk 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 neurologiCdeficits. 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
32. (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
33. (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 symptomatiCin 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 symptomatiCwhereas the older population tend to have aquired enough ankylosis at the level to prevent instability symptoms
■Correct Answer: Females40 to 70 years old
34. (665) Q1-918:
The biceps electromyographiCactivity 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
ElectromyographiCactivity of the biceps is greatest from flexion at 90° in supination indicating that this arCof motion is where there is the most sustained contraction of the biceps muscle
■Correct Answer: Flexion from 90° in supination
35. (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) StatiCadjustable splinting (turnbuckle splint)
2) Local heat
5) Active gentle-assisted stretch
4) DynamiChinged 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 drastiCmeasures are more appropriate treatment methods
■Correct Answer: Closed manipulation
36. (667) Q1-920:
The principle complication of constrained and semiconstrained total elbow arthroplasty is:
1) HeterotopiCbone 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
37. (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
38. (672) Q1-926:
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
39. (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)
40. (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) SciatiCnerve
The sciatiCnerve 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: SciatiCnerve
41. (999) Q1-1306:
The principal thrombogeniCstimulus leading to the production of venous thromboemboliCdisease 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 thrombogeniCfactors 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
42. (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
43. (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 periprosthetiCfracture:
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
44. (1002) Q1-1309:
Which of the following radiographiCchanges 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
45. (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
46. (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
47. (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
48. (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
49. (1007) Q1-1314:
Placement of a screw in the anterior superior quadrant of the acetabulum will place which structure at risk:
1) Internal iliaCartery
3) Common iliaCvein
2) Bladder
5) Common iliaCartery
4) External iliaCvein
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 iliaCvein and the obturator artery, respectively
■Correct Answer: External iliaCvein
50. (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 diagnostiCfor an infection. Mononuclear cells can be present in the face of aseptiCloosening or polywear disease. PMNs are diagnostiCof a biologiCinfectious response.Correct