ORTHOPEDIC MCQS WITH ANSWER HIP 04

1.         During primary total knee arthroplasty, what is the maximum distance the joint line can be raised or lowered before poor motion, joint instability, and increased chance of revision occur?

 

1-         4 mm

2-         8 mm

3-         12 mm

4-         16 mm

5-         20 mm

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Positioning of the femoral and tibial components is a common cause of early failure of total knee arthroplasty.  Two modes of possible position are raising or lowering the joint line from its anatomic level.  Raising or lowering the joint line beyond an established threshold can cause limited range of motion, poor patellar function, and possible instability.  It has been determined that a threshold of approximately 8 mm provides consistently good results after knee arthroplasty.

 

REFERENCE: Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 339-365.

 

 

2.        Figure 1 shows the radiograph of an 18-year-old patient who has severe knee pain.  Treatment consisting of osteotomy should be perfomed

 

1-         above the tibial tubercle.

2-         at or just below the tibial tubercle.

3-         in the tibial diaphysis.

4-         on both the femur and tibia.

5-         on the femur alone.

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Very large corrections of tibial deformity can be achieved at or just below the tibial tubercle.  This level of osteotomy maintains the relationship between the tubercle and the rest of the joint, does not alter patellofemoral mechanics, and avoids complicating possible future conversion to total knee arthroplasty.  High tibial osteotomy is contraindicated for large corrections because of excessive elevation of the tibial tubercle and overhang of the lateral plateau.  Correction in the tibial diaphysis creates a zig zag pattern in the tibia by correcting below the deformity and risks nonunion in cortical bone.  There is no evidence that the femur is deformed; therefore, femoral osteotomy is not indicated. 

 

REFERENCE: Murphy SB: Tibial osteotomy for genu varum: Indications, preoperative planning, and technique. Orthop Clin North Am 1994;25:477-482.

 

3.        Figure 2 shows the AP radiograph of an 18-year-old woman with progressive and severe right hip pain.  Nonsteroidal anti-inflammatory drugs no longer control her pain.  What is the next most appropriate step in management?

 

1-         Total hip arthroplasty

2-         Single innominate (Salter) osteotomy

3-         Chiari osteotomy

4-         Periacetabular osteotomy

5-         Varus intertrochanteric osteotomy

 

PREFERRED RESPONSE: 4

 

DISCUSSION: A concentric hip with acetabular dysplasia in a symptomatic patient is best treated by periacetabular osteotomy.  The Salter osteotomy is less optimal because the method has limited correction, is uniaxial, cannot be tailored to the deformity, and lateralizes the entire hip joint, thereby increasing the joint reactive forces.  Because the hyaline cartilage of the joint is histologically normal, rotating the hyaline cartilage into an optimal position is preferable to augmenting the acetabulum with a shelf or by Chiari osteotomy.  Varus intertrochanteric osteotomy has no significant role in the treatment of acetabular dysplasia.  Total hip arthroplasty may be required in the future but should not be the first choice.

 

REFERENCE: Millis MB, Murphy SB, Poss R: Osteotomies about the hip for the prevention and treatment of osteoarthritis. Instr Course Lect 1996;45:209-226.

 

 

4.        Which of the following findings is a prerequisite for a high tibial valgus osteotomy for medial compartment gonarthrosis?

 

1-         Inflammatory arthritis

2-         Ligamentous instability

3-         Lateral tibial subluxation

4-         Preoperative arc of motion of at least 90 degrees

5-         Narrowing of the lateral compartment cartilaginous joint space

 

PREFERRED RESPONSE: 4

 

DISCUSSION: The indications for high tibial valgus osteotomy include a physiologically young age, arthritis confined to the medial compartment, 10 to 15 degrees of varus alignment on weight-bearing radiographs, a preoperative arc of motion of at least 90 degrees, flexion contracture of less than 15 degrees, and a motivated, compliant patient.  Contraindications include lateral compartment narrowing of the articular cartilage, lateral tibial subluxation of greater than 1 cm, medial compartment bone loss, ligamentous instability, and inflammatory arthritis.

 

REFERENCES: Naudie D, Bourne RB, Rorabeck CH, Bourne TT: The Insall Award: Survivorship of the high tibial valgus osteotomy. A 10- to 22-year followup study. Clin Orthop 1999;367:18-27.

Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000,

pp 255-264.

 

5.         Figures 3a and 3b show the current radiographs of a 58-year-old man who underwent total knee arthroplasty with a cruciate ligament sparing prosthesis 7 years ago.  Examination reveals boggy synovitis and moderate pain, particularly anteriorly.  Management should consist of

 

1-         follow-up radiographs.

2-         alendronate, with follow-up examinations every 6 months.

3-         revision to a posterior stabilized prosthesis.

4-         exchange of the tibial insert through a limited incision.

5-         surgical exploration with revision or exchange based on the findings.

 

PREFERRED RESPONSE: 5

 

DISCUSSION: The patient has symptoms of synovitis that are most likely the result of the release of particles from the tibial polyethylene.  While observation may be warranted in a completely asymtomatic knee, some intervention is indicated for this patient as there is clear radiographic evidence of lysis in both the tibia and femur.  The decision about the extent of the revision should be made at the time of surgery.  A limited incision technique is not indicated.  Grafting (or using graft substitute) the defect is the most appropriate approach for treating the osteolytic lesions.  While a posterior stabilized prosthesis might be the solution, surgical findings might dictate otherwise.

 

REFERENCE: Brassard MF, Insall JN, Scuderi GR: Complications of total knee arthroplasty, in Insall JN, Scott WN (eds): Surgery of the Knee, ed 3. Philadelphia, PA, Churchill Livingstone, 2001, vol 2, pp 1801-1844.

 

 

6.        What is the main benefit of using metal-backed tibial components in total knee arthroplasty?

 

1-         Improve the conformity of the articular surfaces

2-         Reduce the maximum compressive stresses on the underlying cancellous bone

3-         Increase the tensile forces on the other condyle when one is loaded

4-         Decrease the thickness of the polyethylene tray

5-         Decrease the compressive forces on the polyethylene tray

 

PREFERRED RESPONSE: 2

 

DISCUSSION: In a normal knee, the hard subchondral bone helps to distribute loads across the joint surface. A metal-backed tibial component in total knee arthroplasty decreases the compressive stresses on the underlying, softer cancellous bone by distributing the load over a larger surface area, particularly when one condyle is loaded.  Although metallic base plates also increase the tensile forces on the other condyle when one is loaded and may decrease the thickness of the polyethylene tray, these are not benefits. Compressive forces on the polyethylene tray are increased with metal backing.  The conformity of the articular surfaces is not affected by metal backing of the tibial component. 

 

REFERENCE: Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 265-274.

 

 

7.         Figures 4a and 4b show the radiographs of a 32-year-old man who has right groin pain with activity or prolonged standing.  Which of the following factors would not prohibit consideration of acetabular liner exchange and grafting of the defects?

 

1-         Malposition of the components

2-         A poor survivorship record of the implant

3-         A high-powered intraoperative frozen section that reveals a count of 20 WBCs per high-powered field

4-         A nonmodular acetabular component

5-         A well-fixed modular acetabular component

 

PREFERRED RESPONSE: 5

 

DISCUSSION: Polyethylene particles generated as mechanical wear debris can be phagocytized by macrophages and enter a metabolically active state that releases cytokines, causing periprosthetic bone resorption.  Significant osteolysis can occur in the pelvis with a porous-coated cementless socket without loosening of the component.  If the acetabular component is modular, well positioned, well-designed with a good survivorship record, and remains undamaged after liner removal, the polyethylene liner can be exchanged and the lytic defects can be debrided and bone grafted.  This implant is well positioned, has a good survivorship record, a good locking mechanism, and is modular.  The hip arthroplasty needs to be aseptic for consideration of liner exchange.

 

REFERENCES: Maloney WJ, Herzwurm P, Paprosky W, Rubash HE, Engh CA: Treatment of pelvic osteolysis associated with a stable acetabular component inserted without cement as part of a total hip replacement. J Bone Joint Surg Am 1997;79:1628-1634.

Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 417-451.

 

 

8.         A patient who underwent total knee arthroplasty 6 years ago now reports knee pain for the past 3 days following dental surgery.  Cultures of the aspirate are positive for Staphylococcus epidermidis.  Management should consist of

 

1-         IV antibiotics.

2-         arthroscopic irrigation and debridement, following by IV antibiotics.

3-         irrigation and debridement, polyethylene exchange, and IV antibiotics.

4-         one-stage component removal and reimplantation, followed by IV antibiotics.

5-         two-stage component removal and reimplantation, with IV antibiotics in the interim period.

 

PREFERRED RESPONSE: 3

 

DISCUSSION: The patient has an early prosthesis infection as a result of hematogenous seeding from dental surgery.  Irrigation and debridement with polyethylene exchange and IV antibiotics have been successful in early postoperative infections; it is less likely to be effective for a late hematogenous infection.  Immediate total component exchange also may be effective, but it should be reserved for failure of irrigation and debridement.

 

REFERENCES: Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 323-337.

Goldman RT, Scuderi GR, Insall JN: 2-stage reimplantation for infected total knee replacement. Clin Orthop 1996;331:118-124.

 

 

9.         A 32-year-old woman with systemic lupus erythematosus treated with methotrexate and oral corticosteroids reports right groin pain with ambulation and night pain.  Examination reveals pain with internal and external rotation and flexion that is limited to 105 degrees because of discomfort.  Laboratory studies show a serum WBC of 9.0/mm³ and an erythrocyte sedimentation rate of 35 mm/h.  Figures 5a and 5b show AP and lateral radiographs of the right hip.  Further evaluation should include

 

1-         examination under fluoroscopy.

2-         MRI.

3-         a bone scan.

4-         arthrography.

5-         aspiration and arthrography.

 

PREFERRED RESPONSE: 2

 

DISCUSSION: The radiographs show Ficat and Arlet stage 2 osteonecrosis.  The femoral head remains round, and there are sclerotic changes in the superolateral quadrant.  Patients with systemic lupus erythematosus are at risk for osteonecrosis because of prednisone use and the underlying metabolic changes associated with the condition (hypofibrinolysis and thrombophilia).  MRI is the best diagnostic method for detecting osteonecrosis, with a greater than 98% sensitivity and specificity.  For this patient, an MRI can assess the contralateral hip for any involvement and can quantify the extent of the lesion. 

 

REFERENCES: Mont MA, Jones LC, Sotereanos DG, Amstutz HC, Hungerford DS: Understanding and treating osteonecrosis of the femoral head. Instr Course Lect

2000;49:169-185.

Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont , IL, American Academy of Orthopaedic Surgeons, 2002, pp 417-451.

 

10.      An otherwise healthy 57-year-old man has persistent, severe hip pain after undergoing total hip arthroplasty 3 months ago.  What is the next most appropriate step in management?

 

1-         Serial radiographs to assess progressive radiolucency from osteolysis or mechanical loosening

2-         Assessment of C-reactive protein, erythroctye sedimentation rate, and CBC, followed by aspiration

3-         Technetium and/or indium-labeled leukocyte scintigraphy

4-         A trial of broad-spectrum cefalosporin antibiotics to assess for a change in pain intensity

5-         Injection with lidocaine and methylprednisolone acetate

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Any patient who is severely symptomatic this quickly after surgery must be evaluated for infection.  Loosening is also a possible cause, but infection must be ruled-out.  Bone scans are not helpful at this early postoperative stage.  Normal laboratory values argue strongly against infection, but when abnormal, need to be supplemented with a hip aspiration.  Aspiration remains the most selective and sensitive measure, especially when linked to a WBC count of the synovial tissues in the joint.  There is no indication for an antiobiotic trial because it may make future culture sensitivity more difficult. 

 

REFERENCES: Drancourt M, Stein A, Argenson JN, et al: Oral rifampin plus ofloxacin for treatment of staphylococcus-infected orthopedic implants. Antimicrob Agents Chemother 1993;37:1214-1218.

Duncan CP, Beauchamp C: A temporary antibiotic-loaded joint replacement system for the management of complex infections involving the hip. Orthop Clin North Am 1993; 24: 751-759.

Oyen WJ, Claessens RA, van Horn JR, et al: Scintiographic detection of bone and joint infections with indium-111-labeled nonspecifonal human immunoglobulin G. J Nucl Med 1990;31:403-412.

 

 

11.       A 61-year-old man reports right hip pain and limited motion after undergoing total hip arthroplasty for posttraumatic arthritis 1 year ago.  Figure 6 shows an AP radiograph of the pelvis.  To improve motion and relieve pain, management should consist of

 

1-         surgical excision of heterotopic ossification and ethyl hydroxydiphosphonate at a dose of 20 mg/kg of body weight for 3 months.

2-         surgical excision of heterotopic ossification and irradiation of the right hip in a single dose of 400 Gy postoperatively.

3-         surgical excision of heterotopic ossification and irradiation of the right hip in a single dose of 700 Gy postoperatively.

4-         ethyl hydroxydiphosphonate at a dose of 20 mg/kg of body weight for 3 months.

5-         25 mg of oral indomethacin administered three times a day for 10 days.

 

PREFERRED RESPONSE: 3

 

DISCUSSION: The patient has symptomatic grade IV Brooker heterotopic ossification.  Once the bone has matured, it can be excised.  Surgical excision should be combined with postoperative irradiation to avoid recurrence.  Pharmacologic and irradiation intervention are not successful beyond the perioperative period unless they are combined with surgical excision of mature heterotopic ossification.

 

REFERENCES: Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 417-451.

Iorio R, Healy WL: Heterotopic ossification after total hip and total knee arthroplasty: Risk factors, prevention, and treatment. J Am Acad Orthop Surg 2002;10:409-416.

 

 

12.      Osteolysis after total knee arthroplasty can be minimized through prosthetic design features such as

 

1-         modular polyethylene inserts.

2-         use of tibial posts on the tibial insert.

3-         monolithic metal-backed tibial components.

4-         metal-backed patellar components.

5-         cementless tibial implants.

 

PREFERRED RESPONSE: 3

 

DISCUSSION: The incidence of osteolysis is minimal in studies reporting the use of all polyethylene or monolithic metal-backed tibial components.  Osteolysis has been reported in patients with total knee arthroplasties using cementless implants with modular components.  Micromotion between the tibial tray and the polyethylene results in backside wear, leading to osteolysis.  Osteolysis also has been reported in cemented posterior cruciate-substituting modular components.  O’Rourke and associates reported a 16% incidence of osteolysis in patients with a posterior stabilized implant because of the use of modular polyethylene and the subsequent abrasive wear.  Oxidation of the polyethylene that is the result of the method of sterilization and shelf life has also been implicated in the high incidence of osteolysis, along with patient factors such as activity level and weight.  

 

REFERENCE: O’Rourke M, Callaghan J, Goetz D, Sullivan P, Johnson R: Osteolysis associated with a cemented modular posterior cruciate substituting total knee design. J Bone Joint Surgery Am 2002;84:1362-1371.

 

 

13.      What type of cementless femoral fixation results in the highest rate of distal femoral osteolysis?

 

1-         Tapered circumferential proximally porous-coated stem

2-         Hydroxyapatite-coated tapered circumferential proximally porous-coated stem

3-         Straight circumferential fully porous-coated stem

4-         Straight modular circumferential proximally porous-coated sleeve and distal fluted stem

5-         Noncircumferential proximally porous-coated stem

 

PREFERRED RESPONSE: 5

 

DISCUSSION: Despite the relatively few problems with porous-coated cementless stems, stress shielding and thigh pain do occur.  One design feature of proximally coated stems that has been associated with a higher incidence of distal osteolysis is the presence of noncircumferential proximal porous coating.  Tapered, modular with sleeve, and hydroxyapatite proximally porous-coated stems have all performed well.  Fully porous-coated straight stems have a high survivorship rate as well. 

 

REFERENCES: Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 175-180.

Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 417-451.

Emerson RH Jr, Sanders SB, Head WC, Higgins L: Effect of circumferential plasma-spray porous coating on the rate of femoral osteolysis after total hip arthroplasty. J Bone Joint Surg Am 1999;81:1291-1298.

 

 

 

14.      When performing a total knee arthroplasty using modular components, what is the minimum recommended thickness of an ultra-high molecular weight polyethylene insert for a tibial component?

 

1-         3 to 5 mm

2-         6 to 8 mm

3-         10 to 12 mm

4-         13 to 15 mm

5-         Greater than 15 mm

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Polyethylene wear has been identified as a major contributor to failure of total knee implants, of which thickness is an important factor.  Several studies have shown that the minimum thickness should be 6 to 8 mm.  While Wright and Bartel have shown that 6 to 8 mm has been recommended as the minimum thickness of an ultra-high molecular weight polyethylene insert for a tibial component in total knee arthroplasty, more recent work by Meding and associates and Worland and associates has verified the clinical efficacy of 4 mm of polyethylene in compression-molded anatomic graduated nonmodular components.  

 

REFERENCES: Bartel DL, Bicknell VL, Wright TM: The effect of conformity, thickness, and material on stresses in ultra-high molecular weight components for total joint replacement. J Bone Joint Surg Am 1986;68:1041-1051.

Wright TM, Bartel DL: The problem of surface damage in polyethylene total knee components. Clin Orthop 1991;273:261-263.

Meding JB, Ritter MA, Faris PM: Total knee arthroplasty with 4.4 mm of tibial polyethylene: 10-year followup. Clin Orthop 2001;388:112-117.

Worland RL, Johnson G, Alemparte J, Jessup DE, Kennan J, Norambuena N: Ten to fourteen year survival and functional analysis of the AGC total knee replacement system. Knee 2002;9:133-137.

 

 

 

15.       During total knee arthroplasty using a posterior cruciate-retaining design, excessive tightness in flexion is noted, while the extension gap is felt to be balanced.  Which of the following actions will effectively balance the knee?

 

1-         Resect more distal femur.

2-         Resect more anterior tibia.

3-         Use a larger femoral component.

4-         Use a smaller polyethylene insert.

5-         Recess the posterior cruciate ligament.

 

PREFERRED RESPONSE: 5

 

DISCUSSION: Excessive flexion gap tightness can be addressed with a variety of techniques; including: (a) recess and release the posterior cruciate ligament; (b) resect a posterior slope in the tibia; (c) avoid an oversized femoral component that moves the posterior condyles more distally; (d) resect more posterior femoral condyle and use a smaller femoral component placed more anteriorly; and (e) release the tight posterior capsule and balance the collateral ligaments.

 

REFERENCE: Ayers DC, Dennis DA, Johanson NA, Pelligrini VD: Common complications of total knee arthroplasty. J Bone Joint Surg Am 1997;79:278-311.

 

 

 

 

16.      What is the dominant component of articular cartilage extracellular matrix by weight?

 

1-         Water

2-         Collagen

3-         Keratan sulfate

4-         Chondroitin sulfate

5-         Nerve and lymphatic tissue

 

PREFERRED RESPONSE: 1

 

DISCUSSION: Articular cartilage is a highly organized viscoelastic material, and load transmission depends on the specific composition of the extracellular matrix.  Articular cartilage is devoid of neural, lymphatic, and blood vessel tissue.  The extracellular matrix consists of water, proteoglycans, and collagen.  Water comprises most of the wet weight (65% to 80%).  Type II collagen comprises 95% of the collagen.  The collagen and proteoglycan (keratan sulfate and chondroitin sulfate) matrix and its high water content are responsible for the mechanical properties of the articular cartilage.

 

REFERENCES: Buckwalter JA, Mankin HJ: Articular cartilage: Degeneration and osteoarthritis, repair, regeneration, and transplantation. Inst Course Lect 1998;47:487-504.

Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 3-18.

 

 

 

 

17.       A 70-year-old man underwent primary total knee arthroplasty 3 months ago.  Figures 7a and 7b show the radiograph and clinical photograph following incision and drainage of the wound 1 week ago.  Aspiration of the joint reveals methicillin-sensitive Staphylococcus aureus.  What is the next most appropriate step in management?

 

1-         Repeat debridement, followed by 6 weeks of IV antibiotics

2-         Repeat debridement, followed by direct exchange arthroplasty

3-         Delayed exchange reimplantation

4-         Immediate knee arthrodesis

5-         Amputation

 

PREFERRED RESPONSE: 3

 

DISCUSSION: The overriding factor determining treatment in this case is the appearance of the surgical wound.  Based on MacPhearson’s work, this “C” wound is best managed with two-stage exchange.  The functional outcome is markedly diminished following a knee arthrodesis compared to revision knee arthroplasty.

 

REFERENCES: Harwin SF: The diagnosis and management of infected total knee replacement. Seminars Arthroplasty 2002;13:9-22.

Goldmann RT, Scuderi GR, Insall JN: 2-stage reimplantation for infected total knee replacement. Clin Orthop 1996;331:118-124.

Morrey BF, Westholm F, Schoifet S, Rand JA, Bryan RS: Long-term results of various treatment options for an infected total knee arthroplasty. Clin Orthop 1989;248:120-128.

 

 

 

18.       A 35-year-old male laborer with isolated posttraumatic degenerative arthritis of the right hip undergoes the procedure shown in Figure 8.  What is the most appropriate position of the right lower extremity?

 

1-         0 degrees of flexion, 10 degrees of abduction, 0 degrees of rotation

2-         15 degrees of flexion, 20 degrees of abduction, 15 degrees of external rotation

3-         20 degrees of flexion, 10 degrees of abduction, and 5 degrees of external rotation

4-         30 degrees of flexion, 5 degrees of adduction, and 5 degrees of external rotation

5-         45 degrees of flexion, 10 degrees of adduction, 0 degrees of rotation

 

PREFERRED RESPONSE: 4

 

DISCUSSION: The primary indication for hip arthrodesis is isolated unilateral hip disease in a young, active patient.  Avoiding abductor damage and preserving proximal femoral anatomy are imperative to allow conversion to a future total hip arthroplasty.  Optimal positioning is 30 degrees of flexion to allow swing-through.  Neutral abduction and adduction and slight external rotation allow the most efficient gait while allowing sufficient support in stance.  A small degree of adduction is acceptable for a successful hip arthrodesis.

 

REFERENCES: Callaghan JJ, Brand RA, Pedersen DR: Hip arthrodesis: A long term follow-up. J Bone Joint Surg Am 1985;67:1328-1335.

Koval KJ (ed): Orthopaedic Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 417-451.

 

 

 

19.      Which of the following factors can contribute to patellar subluxation following routine total knee arthroplasty?

 

1-         External rotation of the femoral component

2-         Internal rotation of the tibial component

3-         Symmetric patellar resection

4-         Lateral placement of the tibial component

5-         Neutral alignment of the mechanical axis

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Excessive resection of the lateral facet of the patella can lead to subluxation.  Rotational alignment of the components can have a significant impact on patellar tracking.  Internal rotation of the femoral component leads to more lateral alignment of the patella within the trochlear groove.  Internal rotation and medial placement of the tibial component results in lateralization of the tibial tubercle with an increase in the Q angle.  Excessive valgus alignment of the mechanical axis, or insufficient correction of preoperative valgus, has a similar effect on the Q angle, and both can result in a higher rate of tracking problems.

 

REFERENCE: Ayers DC, Dennis DA, Johanson NA, Pelligrini VD: Common complications of total knee arthroplasty. J Bone Joint Surg Am 1997;79:278-311.

 

 

 

 

20.      When an adult hip is surgically dislocated for relief of femoro-acetabular impingment, what is the risk of postoperative iatrogenic osteonecrosis?

 

1-         Less than 2%

2-         2% to 4%

3-         5% to 10%

4-         11% to 20%

5-         More than 20%

 

PREFERRED RESPONSE: 1

 

DISCUSSION: In a report of more than 70 hips treated by surgical dislocation, iatrogenic osteonecrosis failed to develop in any of the hips. 

 

REFERENCE: Ganz R, Gill TJ, Gautier E, Ganz K, Krugel N, Berlemann U: Surgical dislocation of the adult hip: A technique with full access to the femoral head and acetabulum without the risk of avascular necrosis. J Bone Joint Surg Br 2001;83:1119-1124.

 

21.      What is the most frequent late complication of cementless fixation in total knee arthroplasty?

 

1-         Infection

2-         Subluxation of the patella

3-         Loss of motion

4-         Femoral loosening

5-         Osteolysis

 

PREFERRED RESPONSE: 5

 

DISCUSSION: The incidence of osteolysis, particularly around fixation screws in the tibia, can be as high as 30%.  Stable femoral component fixation is generally maintained.  Infection, subluxation of the patella, and stiffness can occur with either cemented or cementless fixation.

 

REFERENCES: Peters PC, Engh GA, Dwyer KA, Vinh TN: Osteolysis after total knee arthroplasty without cement. J Bone Joint Surg Am 1992;74:864-876.

Parks NL, Engh GA, Topoleski LDT, Emperado J: Modular tibial insert micromotion: A concern with contemporary knee implants. Clin Orthop 1998;356:10-15.

 

 

22.      In the treatment of acetabular dysplasia, what type of pelvic osteotomy leaves the “teardrop” in its original position and redirects the acetabulum?

 

1-         Steel

2-         Chiari

3-         Ganz periacetabular

4-         Dial or spherical

5-         Salter innominate

 

PREFERRED RESPONSE: 4

 

DISCUSSION: The dial or spherical osteotomy leaves the medial wall or teardrop in its original position and, as a result, is intra-articular.  The other pelvic osteotomies (except Chiari) redirect the acetabulum, including the medial wall.  The Chiari osteotomy improves coverage without redirecting the acetabulum within the pelvis, and it leaves the teardrop in the same place.

 

REFERENCES: Lack W, Windhager R, Kutschera HP, Engel A: Chiari pelvic osteotomy for osteoarthritis secondary to hip dysplasia: Indications and long-term results. J Bone Joint Surg Br 1991;73:229-234.

Ganz R, Klaue K, Vinh TS, Mast JW: A new periacetabular osteotomy for the treatment of hip dysplasias: Technique and preliminary results. Clin Orthop 1988;232:26-36.

Ninomija S, Tagwa H: Rotational acetabular osteotomy for the dysplastic hip. J Bone Joint Surg Am 1984;66:430.

 

 

 

23.      What is the correct order of the elastic modulus of the following materials from greatest to least?

 

1-         Stainless steel, cobalt-chromium, titanium, polymethylmethacrylate (PMMA), alumina ceramic.

2-         Cobalt-chromium, stainless steel, titanium, alumina ceramic, PMMA

3-         Alumina ceramic, titanium, cobalt-chromium, stainless steel, PMMA

4-         Alumina ceramic, cobalt-chromium, stainless steel, titanium, PMMA

5-         Titanium, cobalt-chromium, alumina ceramic, stainless steel, PMMA

 

PREFERRED RESPONSE: 4

 

DISCUSSION: In Young’s modulus of elasticity, E is a measure of the stiffness of a material and its ability to resist deformation.  In the elastic region of the stress-stain curve, E = stress/strain.  The moduli of elasticity for these materials are alumina ceramic = 380 Gigapascals (GPa), cobalt-chromium = 210 GPa, stainless steel = 190 GPa, titanium = 116 GPa, and PMMA = 1.1 to 4.1 GPa.

 

REFERENCES: Buckwalter JA, Einhorn TA, Simon SR (eds): Orthopaedic Basic Science, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 182-215.

Brinker MR: Basic science section 8: Biomechanics and biomaterials, in Miller MD (ed): Review of Orthopaedics, ed 3. Philadelphia, PA, WB Saunders, 2000, pp 120-123.

 

 

 

24.      Compared to similar patients who do not donate autologous blood, patients with normal baseline hemoglobin who donate autologous blood prior to undergoing primary total hip arthroplasty are likely to

 

1-         receive an allogeneic transfusion.

2-         experience cardiac complications perioperatively.

3-         have a greater likelihood of receiving a transfusion perioperatively.

4-         have a higher hemoglobin at the time of discharge.

5-         have deep venous thrombosis postoperatively.

 

PREFERRED RESPONSE: 3

 

DISCUSSION: Billote and associates compared patients with normal baseline hemoglobin levels who did and did not donate autologous blood prior to total hip arthroplasty.  No patients received allogeneic blood perioperatively, and the autologous donors had significantly lower hemoglobin levels at the time of surgery and in the recovery room.  Of the autologous donors, 69% received an autologous transfusion.  The authors concluded that autologous donation was unnecessary in patients undergoing primary total hip arthroplasty who had a normal hemoglobin.

 

REFERENCES: Billote D, Glisson SN, Green D, Wixson RL: A prospective, randomized study of preoperative autologous donation for hip replacement surgery. J Bone Joint Surg Am 2002;84:1299-1304.

Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 47-53.

 

 

25.      Which of the following best describes the resultant forces on an increased offset stem when compared with a standard offset stem?

 

1-         Increased joint reaction force, increased torsional load

2-         Increased joint reaction force, decreased torsional load

3-         Decreased joint reaction force, increased torsional load

4-         Decreased joint reaction force, decreased torsional load

5-         No change in joint reaction force or torsional load

 

PREFERRED RESPONSE: 3

 

DISCUSSION: The increased emphasis on restoring offset in total hip arthroplasty has implications for the forces applied to the components and the fixation interfaces.  Static analysis has shown that with an increased affect, joint reaction force on the articulation is decreased.  When the resultant load on the hip is “out of plane” (ie, directed anterior to posterior), there is increased torsion where the stem is turned into more retroversion.

 

REFERENCES: Buckwalter JA, Einhorn TA, Simon SR (eds): Orthopaedic Basic Science, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 134-180.

Hurwitz DE, Andriaacchi TP: Biomechanics of the hip, in Callaghan J, Rosenberg AG, Rubash HE (eds): The Adult Hip. Philadelphia, PA, Lippincott-Raven , 1998.

Pauwels F: Biomechanics of the Normal and Diseased Hip. New York, NY, Springer-Verlag, 1976.

 

 

26.      Figure 9 shows the radiograph of a 75-year-old woman who reports the sudden onset of disabling medial knee pain.  What is the most likely diagnosis?

 

1-         Osteoarthritis

2-         Osteonecrosis

3-         Meniscal tear

4-         Metastatic lesion

5-         Synovial osteochondromatosis

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Idiopathic osteonecrosis of the medial femoral condyle occurs predominantly in women older than age 60 years.  It is characterized by pain centered in the medial anterior aspect of the knee, and onset is sudden.  Flattening, sclerosis, and the radiolucent crescent sign are radiographic indicators of osteonecrosis.  The radiographs show no narrowing of the joint space or osteophyte formation to indicate osteoarthritis, and there are no loose bodies to indicate synovial osteochondromatosis.  A meniscal tear is not consistent with the radiographic findings shown here.  Meniscal tears can coexist with osteonecrosis, but the pain is not eliminated merely by partial meniscectomy.  Metastatic lesions to the distal femoral epiphysis are exceedingly rare.

 

REFERENCES: Urbaniak JR, Jones JP Jr (eds): Osteonecrosis: Etiology, Diagnosis, and Treatment. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 413-418.

Insall JN, Windsor RE, Scott WN, Kelly MA, Aglietti P (eds): Surgery of the Knee, ed 2. New York, NY, Churchill Livingstone, 1993, pp 609-634.

 

 

27.      Which of the following statements best characterizes polymethylmethacrylate (PMMA) when it is used to secure joint components in bone and to distribute the forces evenly across the bone-implant interface?

 

1-         PMMA is stronger in tension than compression.

2-         Porosity reduction increases the fatigue strength of PMMA.

3-         Hypotension that occasionally results after PMMA is placed in the femoral canal is independent of a patient’s intraoperative blood volume.

4-         Inclusion of antibiotics does not alter the strength of PMMA.

5-         PMMA bonds chemically to bone and the implant surface.

 

PREFERRED RESPONSE: 2

 

DISCUSSION: PMMA has no adhesive properties and can be more accurately described as grout than glue.  It does not chemically bond to bone or implants; however, mechanical bonding is accomplished with porous or coated components and with cancellous bone.  PMMA is approximately three times stronger in compression than in tension.  Peak blood levels of monomer are usually seen approximately 3 minutes after the cement is placed.  The monomer is cleared by the lungs.  Associated hypotension is more closely related to diminished blood volume than to circulating monomer levels.  High porosity decreases the tensile and fatigue properties of cement.  Manually mixed cement may have porosity as high as 27%.  Porosity may be reduced to less than 1% through vacuum mixing or centrifugation of the cement.  When adding antibiotics to cement, the compressive and tensile forces are not appreciably decreased, but the overall fatigue strength may be reduced.

 

REFERENCES: Canale ST (ed): Campbell’s Operative Orthopaedics, ed 9. St Louis, MO, Mosby, 1998, pp 221-224.

Callaghan JJ, Dennis DA, Paprosky WG, Rosenberg AG (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1995, pp 27-33.

 

 

28.      During primary total knee arthroplasty, the trial components are in place.  The extensor space is tight, but the flexion space is normal.  What is the best gap balancing solution?

 

1-         Decrease the thickness of the tibial insert.

2-         Upsize the femoral component and distally augment the femur.

3-         Resect additional distal femoral bone. 

4-         Resect additional distal femoral bone and proximal tibial bone.

5-         Resect the proximal tibial bone and distally augment the femoral component.

 

PREFERRED RESPONSE: 3

 

DISCUSSION: The first rule of total knee arthroplasty is to restore the joint line to its original location.  This will ensure optimal patellofemoral biomechanics and will facilitate ligament balancing.  Changes on the tibial side affect both the flexion and extension gaps equally.  Changes in femoral component sizing or position affect the flexion gap only.  Tibial changes affect both the flexion and extension gaps.  To convert a tight extension gap to a normal flexion gap, more distal femur needs to be resected.

 

REFERENCES: Vince KG: Revision knee arthroplasty technique. Instr Course Lect 1993;42:325-339.

Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 513-536.

 

29.      Which of the following methods is considered effective in decreasing the dislocation rate following a total hip arthroplasty using a posterior approach to the hip?

 

1-         Use of a shorter neck length

2-         Use of a smaller diameter head with a skirted neck extension

3-         Reconstruction of the external rotators and capsular attachments during closure

4-         Placement of the acetabular component in 60 degrees of abduction as opposed to 45 degrees of abduction

5-         Placement of the acetabular component in neutral (0 degrees) anteversion as opposed to 15 to 20 degrees of anteversion

 

PREFERRED RESPONSE: 3

 

DISCUSSION: A total hip arthroplasty using the posterior approach has resulted in hip dislocation under certain circumstances.  Reconstruction of the external rotator/capsular complex is recognized as a stability-enhancing mechanism for the posterior approach.  During the procedure, the acetabular component should be placed in 15 to 20 degrees of anteversion and approximately 45 degrees of abduction.  Relative retroversion is a risk factor for posterior dislocation.  High abduction angles result in edge loading of the polyethylene and possible early failure, as well as an increased risk of dislocation.  Smaller diameter heads and skirted neck extensions used together decrease the range of motion that is allowed before impingement occurs, and this can result in dislocation.  Shorter neck lengths generally result in soft-tissue envelope laxity.  If laxity occurs, increased offset, neck length, or both can improve stability. 

 

REFERENCES: Pellicci PM, Bostrom M, Poss R: Posterior approach to total hip replacement using enhanced posterior soft tissue repair. Clin Orthop 1998;355:224-228.

Morrey BF: Difficult complications after hip joint replacement: Dislocation. Clin Orthop 1997;344:179-187.

 

30.      Which of the following treatments of polyethylene results in the highest amount of oxidative degradation? 

 

1-         Ethylene oxide sterilization

2-         Gamma irradiation in air

3-         Gamma irradiation in an inert environment

4-         Gamma irradiation followed by cross-linking

5-         Gas plasma sterilization

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Oxidative degradation of polyethylene occurs as a function of time in an air environment.  In an environment such as argon, nitrogen, or a vacuum, the process is reduced.  Ethylene oxide is an alternative for sterilization in which the cross-link degradation is minimized because of the absence of oxidative interactions. Gamma sterilization or use of ethylene oxide gas is the industry standard; however, oxygen concentrations are now reduced to a minimal level to retard the oxidation phenomenon.

 

REFERENCES: Sanford WM, Saum KA: Accelerated oxidative aging testing of UHMWPE. Trans Orthop Res Soc 1995;20:119.

Sun DC, Schmidig G. Stark C, et al: On the origins of a subsurface oxidation maximum and its relationship to the performance of UHMWPE implants. Trans Soc Biomater 1995;18:362.

Callaghan JJ, Dennis DA, Paprosky WA, Rosenberg AG (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1995, pp 35-41.

McKellup HA: Bearing surfaces in total hip replacement: State of the art and future developments. Instr Course Lect 2001;50:165-179.

 

 

31.      Figures 10a through 10c show the radiographs of an 85-year-old man who underwent a revision total knee arthroplasty for loosening of the tibial component 6 months ago.  He now reports a mildly uncomfortable mass on the anterior part of the knee joint.  Examination reveals 95 degrees of motion and good quadriceps strength, and he can ambulate with minimal pain with a walker.  History reveals chronic lymphocytic leukemia for which he is taking antineoplastic medication.  Culture of the mass aspirate grew Candida albicans on two separate occasions.  The patient and the family strongly prefer nonsurgical management.  If long-term suppression is chosen as treatment, what advice should be given to the patient and family?

 

1-         There is a less than a 50% chance of long-term success.

2-         There will be no significant increase in pain or swelling.

3-         Close clinical and laboratory follow-up is not necessary.

4-         Weight bearing and ambulation should be curtailed.

5-         Weight bearing and ambulation are allowed but only with bracing.

 

PREFERRED RESPONSE: 1

 

DISCUSSION: In patients with infected implants, treatment usually involves debridement and exchange of the infected components.  In rare cases, when there is severe comorbidity and immune system compromise, as there is with this patient, a form of chronic suppression is indicated.  This patient’s function is quite satisfactory and, even though there is only a 21% to 38% chance of success (Hirawaka as quoted by Mulvey and Thornhill), an attempt at suppression therapy is indicated.  The patient must be followed closely to monitor the potential complications of long-term antifungal therapy and to monitor the integrity of the joint, looking for bone or soft-tissue destruction.  Because the patient has satisfactory motion and quadriceps strength, no bracing or other assistive device (except for the walker he is now using) is indicated.

 

REFERENCE: Mulvey TJ, Thornhill TS: Infected total knee arthroplasty, in Insall JN, Scott WN (eds): Surgery of the Knee, ed 3. Philadelphia, PA, Churchill Livingstone, 2001, vol 2,
pp 1857-1890.

 

 

32.      Consider the theoretic articulation shown in Figure 11 as femoral and tibial components of a total knee prosthesis in which the components fit like a “roller in trough.”  Which of the following best describes the articulation?

 

1-         Constrained to anteroposterior translation, unconstrained to medial-lateral translation, high contact stress on edge (ie, varus-valgus) loading

2-         Constrained to anteroposterior translation, unconstrained to medial-lateral translation, low contact stress on edge (ie, varus-valgus) loading

3-         Unconstrained to anteroposterior translation, constrained to medial-lateral translation, high contact stress on edge (ie, varus-valgus) loading

4-         Unconstrained to anteroposterior translation, constrained to medial-lateral translation, low contact stress on edge (ie, varus-valgus) loading

5-         Constraint is dependent on the status of the posterior cruciate ligament

 

PREFERRED RESPONSE: 1

 

DISCUSSION: The theoretic total knee components will resist anteroposterior motion by making the femoral component “climb the walls” of the tibial component.  As drawn, there is no constraint to medial-lateral translation.  The cylinder is not rounded on the edges, so varus-valgus motion will impart load from the cylinder to the trough over a small area, thus having a high contact stress.

 

REFERENCE: Alicea J: Scoring systems and their validation for the arthritic knee, in Insall JN, Scott WN (eds): Surgery of the Knee, ed 3. Philadelphia, PA, Churchill Livingstone, 2001, vol 2, pp 1507-1515.

 

 

 

33.      A 45-year-old man underwent unipolar hemiarthroplasty reconstruction using cementless fixation for nontraumatic osteonecrosis of the femoral head 5 years ago.  He now reports buttock and groin pain that is associated with loading activities.  What is the most likely cause of his pain?

 

1-         Infection

2-         Stem loosening

3-         Acetabular osteonecrosis

4-         Acetabular cartilage degeneration

5-         Referred pain from the lumbar spine

 

PREFERRED RESPONSE: 4

 

DISCUSSION: One of the most common complications of hemiarthroplasty is acetabular cartilage degeneration, resulting in increasing pain.  Conversion total hip arthroplasty generally is successful with placement of an acetabular cup.  Additionally, many patients with osteonecrosis already have degenerative changes of the acetabular cartilage even though radiographic findings may appear normal.

 

REFERENCES: Steinberg ME, Corces A, Fallon M: Acetabular involvement in osteonecrosis of the femoral head. J Bone Joint Surg Am 1999;81:60-65.

Dalldorf PG, Banas MP, Hicks DG, Pelligrini VD Jr: Rate of degeneration of human acetabular cartilage after hemiarthroplasty. J Bone Joint Surg Am 1995;77:877-882.

 

 

 

 

34.      Which of the following factors is associated with decreases in active periprosthetic osteolysis in total hip arthroplasty?

 

1-         Large heads in metal-on-polyethylene articulations

2-         Modular acetabular components

3-         Circumferential porous coating

4-         Sterilization of polyethylene by gamma irradiation with storage in air

5-         Supplemental screw fixation

 

PREFERRED RESPONSE: 3

 

DISCUSSION: A 32-mm head design results in less linear wear but more volumetric wear particles.  Modular components that allow motion between the polyethylene insert and the shell can result in backside wear.  The oxidative degradation of gamma-irradiated polyethylene stored in air leads to increased wear.  All of these factors lead to a greater particulate load and more osteolysis.  Circumferential porous coating blocks ingrowth of particle-laden fluid and decreases osteolysis.

 

REFERENCES: Bartel DL, Bicknell VL, Wright TM: The effect of conformity, thickness, and material on stresses in ultra-high molecular weight components for total joint replacement. J Bone Joint Surg Am 1986;68:1041-1051.

Fisher J, Hailey JL, Chan KL, et al: The effect of aging following irradiation on the wear of UHMWPE. Trans Orthop Res Soc 1995;20:12.

Archibeck MJ: The basic science of periprosthetic osteolysis. Instr Course Lect
2001;50:185-195.

 

 

 

35.      When using highly cross-linked ultra-high molecular weight polyethylene as an articulating surface for total knee arthroplasty, what property of the material raises concern?

 

1-         Decreased volumetric wear

2-         Decreased ductility

3-         Increased mobility of the ultra-high molecular weight polyethylene chains in the material

4-         Increased fatigue resistance

5-         Increased fracture toughness

 

PREFERRED RESPONSE: 2

 

DISCUSSION: The decreased mobility of the polymer chains from cross-linking leads to decreased volumetric wear but also to decreases in ductility and fatigue resistance.  Stresses at the knee are higher and varied in the point of application, leading to the concern for fatigue resistance and fracture.

 

REFERENCE: Koval KJ (ed): Orthopaedic Knowlegde Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 193-199.

 

 

 

36.      The diagnosis of an infection after total knee arthroplasty is most reliably proven based on what single study?

 

1-         Leukocyte count and C-reactive protein

2-         Radiographs

3-         Technetium Tc 99m and gallium bone scans

4-         Aspiration of joint fluid

5-         MRI

 

PREFERRED RESPONSE: 4

 

DISCUSSION: In a study of 52 patients with infected total knee arthroplasties, Windsor and associates showed that the average leukocyte count was 8,300/mm³ and that aspirated knee fluid was positive in all patients except one.  Knee radiographs can be unclear in showing infection, which may be present without radiographic signs of loosening.  Technetium Tc 99m and gallium bone scans may not conclusively show the presence of infection, particularly in the first 3 years after knee arthroplasty.

 

REFERENCES: Windsor RE, Bono JV: Infected total knee replacements. J Am Acad Orthop Surg 1994;2:44-53.

Windsor RE, Insall JN, Urs WK, et al: Two-stage reimplantation for the salvage of total knee arthroplasty complicated by infection: Further follow-up and refinement of indications. J Bone Joint Surg Am 1990;72:272-278.

 

 

 

37.      A 48-year-old woman has knee pain that is worse with weight bearing.  She reports no night pain or pain at rest.  History reveals that she underwent total knee arthroplasty with cementless components 2 years ago.  Examination reveals tenderness along the medial joint line.  Figures 12a through 12c show radiographs and a bone scan.  What is the most likely cause of the patient’s pain?

 

1-         Deep infection

2-         Malalignment

3-         Fibrous ingrowth of the femoral component

4-         Fibrous ingrowth of the tibial component

5-         Patellar component loosening

 

PREFERRED RESPONSE: 4

 

DISCUSSION: The radiographs show a halo-like sclerotic margin around the tibial stem and lucency under the baseplate.  The bone scan shows markedly increased uptake under the tibial component, particularly on the medial side (not diffusely through the knee as seen with infection).  These studies indicate lack of bone ingrowth fixation of the cementless porous-coated tibial component.  The recent report of Fehring and associates has identified failure of ingrowth of a porous-coated implant as a dominant mode of early failure of total knee arthroplasties.

 

REFERENCES: Fehring TK, Odum S, Griffin WL, Mason B, Nadaud M: Early failures of total knee arthroplasty. Clin Orthop 2001;392:315-318.

Fehring TK: Revision TJA corrects flexion extension gap imbalance. Orthop Today 2002;22:44.

 

 

 

38.      A 65-year-old man who underwent cemented right total hip arthroplasty 6 years ago now reports acute pain for the past week.  He denies any trauma, recent illnesses, or symptoms other than pain.  Plain radiographs show possible loosening of the femoral component.  A normal result from which of the following studies will most specifically rule out infection?

 

1-         Technetium Tc 99m bone scan

2-         Hip aspiration

3-         Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)

4-         WBC count

5-         MRI

 

PREFERRED RESPONSE: 3

 

DISCUSSION: A patient with an infected total hip arthroplasty may lack the symptoms of fever, chills, redness, or increased warmth typical of septic arthritis.  Sensitivity for ESR and CRP ranges from 61% to 96%, and specificity ranges from 85% to 100%.  Technetium Tc 99m bone scans are costly and time-consuming and will not differentiate between septic and aseptic loosening.  Hip aspiration has a false-positive rate of up to 15%, although it may be useful in this patient to further complement the clinical picture if the ESR and CRP are elevated.  The WBC count is rarely elevated in infected total hip arthroplasty.  MRI is expensive and is not indicated for the diagnosis; however, it can aid in identifying intrapelvic extension of a periprosthetic abscess.

 

REFERENCES: Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 455-492.

Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000,
pp 137-148.

 

 

39.      Which of the following procedures is included in third-generation cement technique? 

 

1-         Addition of antibiotic to the cement

2-         Monomer chilling to increase working time and lower viscosity

3-         Porosity reduction through centrifugation and/or vacuum mixing

4-         Use of a cemented, polished, tapered stem

5-         Placement of a plastic tube distally to allow fluid to escape

 

PREFERRED RESPONSE: 3

 

DISCUSSION: The so-called third-generation cement technique adds porosity reduction techniques, centralization devices, and surface modifications to the femoral component.  The surgeon must be aware of the meaning of the various generations of cement technique when interpreting the results presented at meetings and in the literature.

 

REFERENCES: Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 181-193.

Maloney WJ, Hartford JM: The cemented femoral component, in Callaghan JJ, Rosenberg AG, Rubash HE (eds): The Adult Hip. Philadelphia, PA, Lippincott-Raven, 1998, vol 2, pp 959-979.

 

 

 

40.      Which of the following acetabular cup designs has shown the greatest survivorship at 10 years in patients younger than age 60 years?

 

1-         Cemented polyethylene socket

2-         Cemented metal-backed socket

3-         Cementless hydroxyapatite-coated smooth metal-backed socket

4-         Cementless threaded metal-backed socket

5-         Cementless porous-coated metal-backed socket

 

PREFERRED RESPONSE: 5

 

DISCUSSION: Poor survivorship of cemented sockets in young patients has lead to the development of a variety of cementless designs.  Of these, smooth metal-backed sockets have not performed as well as porous-coated designs.  Threaded metal-backed sockets showed a 6% to 25% revision rate secondary to aseptic loosening at a mean follow-up of 4.5 to 6 years.  Despite some early failed designs, cementless porous-coated metal-backed sockets have shown the best survivorship in long-term studies.

 

REFERENCES: Smith SE, Harris WH: Total hip arthroplasty performed with insertion of the femoral component with cement and the acetabular component without cement: Ten to thirteen-year study. J Bone Joint Surg Am 1997;79:1827-1833.

Pellicci PM, Tria AJ Jr, Garvin KL, (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 195-206.

 

 

 

41.      What is the most common donor site complication following a free vascularized fibular graft for osteonecrosis of the femoral head?

 

1-         Sensory deficit

2-         Motor deficit

3-         Flexor hallucis longus contracture

4-         Deep venous thrombosis

5-         Fibular fracture

 

PREFERRED RESPONSE: 1

 

DISCUSSION: Urbaniak and Harvey reported donor site morbidity following free vascularized fibular graft in 198 consecutive patients.  At a 5-year follow-up, they reported overall complications in 24% of the patients.  The most common complication was a sensory deficit (11.8%), followed by motor weakness (2.7%), flexor hallucis longus contracture (2%), and deep venous thrombosis (less than 1%).

 

REFERENCE: Urbaniak J, Harvey E: Revascularization of the femoral head in osteonecrosis. J Am Acad Orthop Surg 1998;6:44-54.

 

 

42.      A 77-year-old woman who underwent a cemented total hip arthroplasty 10 years ago now reports groin pain.  Examination reveals a loosened acetabular component and a well-fixed femoral component.  Treatment should consist of revision of

 

1-         the acetabular component only using a cemented implant.

2-         the acetabular component only using a cementless implant.

3-         both components using cemented implants.

4-         both components using cementless implants.

5-         the acetabular component using a cementless implant and revision of the femoral component using a cemented implant.

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Recent literature supports retention of well-fixed cemented femoral components when revising loosened cemented acetabular components.  Current literature also supports the use of cementless components for revision of loosened cemented acetabular components.

 

REFERENCES: Peters CL, Kull L, Jacobs JJ, Rosenberg AG, Galante JO: The fate of well fixed cemented femoral components left in place at the time of revision of the acetabular component. J Bone Joint Surg Am 1997;79:701-706.

Poon ED, Lachiewicz PF: Results of isolated acetabular revisions: The fate of the unrevised femoral component. J Arthroplasty 1998;13:42-49.

Moskal JT, Shen FH, Brown TE: The fate of stable femoral components retained during isolated acetabular revision: A six- to twelve-year follow-up study. J Bone Joint Surg Am
2002;84:250-255.

Templeton JE, Callaghan JJ, Goetz DD, Sullivan PM, Johnston RC: Revision of a cemented acetabular component to a cementless acetabular component. A ten- to fourteen-year follow-up study. J Bone Joint Surg Am 2001;83:1706-1711.

 

 

 

43.      Which of the following findings is a relative contraindication to primary total knee arthroplasty?

 

1-         Incompetent anterior cruciate ligament

2-         Incompetent posterior cruciate ligament

3-         Incompetent extensor mechanism

4-         Flexion contracture of 20 degrees

5-         Previous high tibial valgus osteotomy

 

PREFERRED RESPONSE: 3

 

DISCUSSION: Contraindications to primary total knee arthroplasty include active infection, an incompetent extensor mechanism, compromised vascularity in the extremity, and local neurologic disruption affecting the competence of the musculature about the knee.  Anterior cruciate, posterior cruciate, or lateral ligament incompetence can be managed with primary total knee arthroplasty.  Mild flexion contracture and previous high tibial valgus osteotomy are not contraindications to primary total knee arthroplasty. 

 

REFERENCE: Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 513-536.

 

 

 

44.      Risk of fat embolism is greatest during what step of total hip arthroplasty?

 

1-         Osteotomy of the femoral neck

2-         Dislocation of the hip

3-         Broaching of the femoral canal

4-         Insertion of a cemented femoral stem

5-         Insertion of a cementless femoral stem

 

PREFERRED RESPONSE: 4

 

DISCUSSION: Embolization of fat and bone marrow elements during total hip arthroplasty has been studied intraoperatively using transesophageal echocardiography.  These studies showed the occurrence of a large number of embolic events during the insertion of a cemented femoral stem.  Embolic events were rare during insertion of a cementless stem.  Femoral broaching caused some embolic events, but they were not nearly as significant as those that occurred following insertion of a cemented stem.  Additionally, relocation of the cemented hip was accompanied by significant embolic events.  This may be related to the untwisting of blood vessels, with the subsequent release of emboli that were most likely generated during insertion of a cemented femoral stem.

 

REFERENCES: Pitto RP, Koessler M, Kuehle JW: Comparison of fixation of the femoral component without cement and fixation with use of a bone-vacuum cementing technique for the prevention of fat embolism during total hip arthroplasty. J Bone Joint Surg Am
1999;81:831-843.

Christie J, Burnett R, Potts HR, Pell AC: Echocardiography of transatrial embolism during cemented and uncemented hemiarthroplasty of the hip. J Bone Joint Surg Br 1994;76:409-412.

 

 

 

 

45.      Venous thrombolembolism is a common complication following total hip and total knee arthroplasty; therefore, prophylaxis is deemed efficacious. Several studies on low-molecular-weight heparin (LMWH) have shown which of the following findings?

 

1-         LMWH is associated with bleeding complications of less than 1% and may be administered immediately after surgery.

2-         LMWH is superior to adjusted-dose warfarin.

3-         LMWH acts on several sites of the coagulation cascade, with its principal action inhibition of factor 10a.

4-         LMWH and unfractionated heparin are equally likely to cause thrombocytopenia.

5-         LMWH may be used in conjunction with regional anesthesia and is not contraindicated in patients with indwelling epidural catheters.

 

PREFERRED RESPONSE: 3

 

DISCUSSION: Prophylactic LMWH is associated with a risk of bleeding complications, especially if administered too soon after surgery.  The risk of major bleeding is 0.3% for control, 0.4% for aspirin, 1.3% for warfarin, 1.8% for LMWH, and 2.6% for unfractionated heparin.  Colwell and associates conducted a prospective, randomized trial on over 1,500 total hip arthroplasty patients.  Overall, the risk of clinically apparent venous thrombolembolism was 3.6% for LMWH and 3.7% for warfarin.  LMWH acts in several sites of the coagulation cascade, with its principal action being inhibition of factor 10a.  Thrombocytopenia is less common with LMWH than with unfractionated heparin.  The use of LMWH is a relative contraindication with indwelling epidural anesthesia. 

 

REFERENCES: Colwell CW Jr, Collis DK, Paulson R, et al: Comparison of enoxaparin and warfarin for the prevention of venous thromboembolic disease after total hip arthroplasty:. Evaluation during hospitalization and three months after discharge. J Bone Joint Surg Am 1999;81:932-940.

Salvati EA, Pelligrini VD Jr, Sharrock NE, et al: Recent advances in venous thromboembolic prophylaxis during and after total hip replacement. J Bone Joint Surg Am 2000;82:252-270.

 

 

 

46.      Wear particles of ultra-high molecular weight polyethylene that are generated by total hip implants are predominantly of what diameter?

 

1-         Less than 1 micron

2-         10 to 50 microns

3-         100 to 200 microns

4-         500 to 750 microns

5-         Greater than 1,000 microns

 

PREFERRED RESPONSE: 1

 

DISCUSSION: Multiple studies have shown that the size of an ultra-high molecular weight polyethylene particle generated by total hip implants is typically less than 1 micron.  This finding is significant in that particles of that size are readily phagocytized by macrophages. 

 

REFERENCES: Campbell P, Ma S, Yeom B, McKellop H, Schmalzried TP, Amstutz HC: Isolation of predominantly submicron-sized UHMWPE wear particles from periprosthetic tissues. J Biomed Mater Res 1995;29:127-131.

Shanbhag AS, Jacobs JJ, Glant TT, Gilbert JL, Black J, Galante JO: Composition and morphology of wear debris in failed uncemented total hip replacement. J Bone Joint Surg Br 1994;76:60-67.

Maloney WJ, Smith RL, Schmalzried TP, Chiba J, Huene D, Rubash H: Isolation and characterization of wear particles generated in patients who have had failure of a hip arthroplasty without cement. J Bone Joint Surg Am 1995;77:1301-1310.

 

 

 

47.      Osteoporosis is best diagnosed by

 

1-         risk factors.

2-         Singh index.

3-         a bone mineral density T score.

4-         increased osteoid formations in lamellar bone.

5-         a family history of disorders related to osteoporosis.

 

PREFERRED RESPONSE: 3

 

DISCUSSION: Risk factors can suggest the existence of osteoporosis.  However, definitive testing, based on the use of bone densitometry measurements, uses the T score in which an average score is taken from a normal population of young women.  The presence of increased osteoid in lamellar bone is seen in osteomalacia but not osteoporosis.  The presence of fractures is evidence of a risk factor for osteoporosis and can predict future fractures, but it does not definitively confirm the diagnosis.  The Singh index is a radiographic finding that is not as accurate as bone mineral density scores.

 

REFERENCE: Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 141-154.

 

 

48.      When compared to patients with osteoarthritis, patients with ankylosing spondylitis undergoing total hip arthroplasty can expect a

 

1-         decreased risk of heterotopic ossification.

2-         higher hip pain score.

3-         lower level of functional return.

4-         comparable infection rate.

5-         comparable level of blood loss.

 

PREFERRED RESPONSE: 3

 

DISCUSSION: Joshi and associates reported a 96% incidence of pain relief in 181 total hip arthroplasties in patients with ankylosing spondylitis.  Only 65% of patients had good to excellent functional results, primarily the result of associated systemic diseases and spinal deformity.  The incidence of infection was slightly higher, and the incidence of heterotopic ossification was higher in this group of patients. 

 

REFERENCE: Joshi A, Markovic L, Hardinge K, Murphy J: Total hip arthroplasty in ankylosing spondylitis: An analysis of 181 hips. J Arthroplasty 2002;17:427-433.

 

 

 

49.      What postoperative complication occurs at a significantly higher rate in patients undergoing bilateral simultaneous total knee arthroplasty than in patients undergoing unilateral total knee arthroplasty?

 

1-         Aseptic loosening

2-         Mortality

3-         Infection

4-         Bleeding

5-         Limited motion requiring manipulation

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Parvizi and associates studied the 30-day mortality rate after more than 22,000 total knee arthroplasties and found that the rate after bilateral total knee arthroplasty was significantly higher than after unilateral total knee arthroplasty.  Aseptic loosening, bleeding, and range of motion have not been shown to be statistically different between patients who had unilateral and simultaneous bilateral total knee arthroplasty.

 

REFERENCE: Parvizi J, Sullivan TA, Trousdale RT, Lewallen DG: Thirty-day mortality after total knee arthroplasty. J Bone Joint Surg Am 2001;83:1157-1161.

 

 

 

 

50.      Metal-on-metal articulation has been reintroduced because of concern about polyethylene wear.  This type of articulation is considered favorable because

 

1-         metal particles are inert.

2-         metal particles are larger than polyethylene particles.

3-         the surfaces can now be fabricated with low carbon, machined cobalt-chromium.

4-         less than 0.6 mm³ of metallic debris are generated per year.

5-         electrochemical problems of the articulation have now been solved through passivation.

 

PREFERRED RESPONSE: 4

 

DISCUSSION: The improvements in metal-on-metal bearing surfaces come from the nonlinear wear rate and smaller particle size of the high carbon wrought material.  Extremely low rates of wear have been demonstrated with high carbon metal-on-metal implants.  There is no significant electrochemical effect of mating two like materials in vivo.

 

REFERENCE: Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 25-34.

 

 

51.       During total knee arthroplasty, what component position aids in proper tracking and stability of the patellar component?

 

1-         Femoral component in external rotation

2-         Tibial component in internal rotation

3-         Medialization of the tibial tray

4-         Lateralization of the patellar component

5-         Medialization of the femoral component

 

PREFERRED RESPONSE: 1

 

DISCUSSION: The femoral component should be implanted with enough external rotation to facilitate patellar tracking.  Proper tracking requires a normal Q angle and is affected by axial and rotational alignment of the femur and tibia.  An excessive Q angle can result from internal rotation of either component, medialization of the tibial tray, or lateralization of the patellar component. 

 

REFERENCES: Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 559-582.

Lonner JH, Lotke PA: Aseptic complications after total knee arthroplasty. J Am Acad Orthop Surg 1999;7:311-324.

 

 

 

 

52.      An otherwise healthy 57-year-old woman has limited range of motion and moderate effusion after undergoing total knee arthroplasty 6 months ago.  One of two cultures of joint aspirate reveals methicillin-resistant Staphylococcus epidermidis.  Management should now consist of

 

1-         repeat aspiration to rule out culture contamination.

2-         IV administration of kanamycin for 6 weeks, followed by suppressive oral antibiotics.

3-         removal of the implant and 6 weeks of antibiotics, followed by reimplantation.

4-         removal of the implant, followed by knee fusion.

5-         open irrigation of the implant and intraoperative cultures, followed by 6 weeks of antibiotics.

 

PREFERRED RESPONSE: 3

 

DISCUSSION: The rapidly increasing prevalence of infection from Staphylococcus epidermidis has made this the most frequently cultured organism.  In most patients, the infection occurred intraoperatively, thereby resulting in a chronic infection if not detected within the first 6 weeks after surgery.  Irrigation of the joint may be successful during this time in 60% of patients, but the most successful treatment is extirpation for 6 weeks, followed by delayed reimplantation.  This approach may result in a salvage rate of as high as 90% in some patients.

 

REFERENCES: Drancourt M, Stein A, Argenson JN, et al: Oral rifampin plus ofloxacin for treatment of staphylococcus-infected orthopedic implants. Antimicrob Agents Chemother 1993;37:1214-1218.

Duncan CP, Beauchamp C: A temporary antibiotic-loaded joint replacement system for the management of complex infections involving the hip. Orthop Clin North Am 1993;24:751-759.

Oyen WJ, Claessens RA, van Horn JR, et al: Scintiographic detection of bone and joint infections with indium-111-labeled nonspecifonal human immunoglobulin G. J Nucl Med 1990;31:403-412.

 

 

 

53.      Figure 13 shows the radiographs of a 56-year-old woman who has pain and varus knee deformity after undergoing total knee arthroplasty 8 years ago.  Aspiration and studies for infection are negative.  During revision surgery, management of the tibial bone loss is best achieved by

 

1-         a custom tibial implant.

2-         a hinged prosthesis.

3-         reconstruction with structural allograft.

4-         reconstruction with iliac crest bone graft.

5-         filling the defect with cement.

 

PREFERRED RESPONSE: 3

 

DISCUSSION: Massive bone loss encountered in revision total knee arthroplasty remains a significant challenge.  Recent reports have shown high success rates using structural allograft to reconstruct massive bone defects.  Custom and hinged prostheses in this setting are no longer favored.  The defect shown is segmental and is too large to be filled with cement or iliac crest bone graft.

 

REFERENCES: Mow CS, Wiedel JD: Structural allografting in revision total knee arthroplasty. J Arthroplasty 1996;11:235-241.

Engh GA, Herzwurm PJ, Parks NL: Treatment of major defects of bone with bulk allografts and stemmed components during total knee arthroplasty. J Bone Joint Surg Am 1997;79:1030-1039.

Clatworthy MG, Ballance J, Brick GW, Chandler HP, Gross AE: The use of structural allograft for uncontained defects in revision total knee arthroplasty: A minimum five-year review. J Bone Joint Surg Am 2001;83:404-411.

 

54.      Varus intertrochanteric osteotomy for coxa valga commonly produces which of the following results?

 

1-         Decreased abductor lever arm

2-         Increased hip joint reaction force

3-         Increased center edge angle

4-         Abductor lag and lurch

5-         Lengthening of the leg

 

PREFERRED RESPONSE: 4

 

DISCUSSION: The greater trochanter is raised as a by-product of varus osteotomy, and a temporary abductor lag and lurch is common for 6 months following surgery.  In the absence of hip joint subluxation, varus intertrochanteric osteotomy has no effect on the center edge angle of Wiberg.  Varus osteotomy typically increases femoral offset, thereby improving the abductor lever arm and reducing the hip joint reaction force.  Even without taking a wedge, varus osteotomy always produces some degree of shortening.

 

REFERENCE: Millis MB, Murphy SB, Poss R : Osteotomies about the hip for the prevention and treatment of osteoarthrosis.  Instr Course Lect 1996;45:209-226.

 

 

55.      A 65-year-old woman has nausea, vomiting, and abdominal distention after undergoing total knee arthroplasty 48 hours ago.  An abdominal radiograph is shown in Figure 14.  Associated risk factors for this disorder include

 

1-         hypokalemia.

2-         administration of warfarin.

3-         administration of antibiotics.

4-         general anesthesia.

5-         early mobilization and physical therapy.

 

PREFERRED RESPONSE: 1

 

DISCUSSION: The prevalence of postoperative ileus associated with total joint arthroplasty has been reported to be as high as 3%.  Metabolic abnormalities such as hypokalemia are believed to contribute to the onset of ileus and Ogilvie’s syndrome (acute pseudo-obstruction of the colon).  Prolonged bed rest also has been associated with the development of ileus and Ogilvie’s syndrome.  Untreated Ogilvie’s syndrome can result in cecal perforation.  Ileus usually is not accompanied by mechanical obstruction.  Antibiotic administration and the type of anesthesia used have not been correlated with development of ileus.  Administration of warfarin has been associated with elevated prothrombin time/partial thromboplastin time and international normalized ratio levels when ileus is managed with a nasogastric tube and suction.  Metabolic imbalances must be corrected to reverse the ileus process.

 

REFERENCES: Iorio R, Healy WL, Appleby D: The association of excessive warfarin anticoagulation and postoperative ileus after total joint replacement surgery. J Arthroplasty 2000;15:220-223.

Clarke HD, Berry DJ, Larson DR: Acute pseudo-obstruction of the colon as a postoperative complication of hip arthroplasty. J Bone Joint Surg Am 1997;79:1642-1647.

 

 

 

56.      A 77-year-old woman with osteoporosis who underwent cemented total hip arthroplasty 12 years ago fell down a flight of stairs.  A radiograph is shown in Figure 15.  What is the best option for treating this fracture?

 

1-         Revision to a long stem prosthesis with impaction grafting

2-         Revision to a long stem prosthesis, bypassing the defect

3-         Proximal femoral allograft reconstruction

4-         Cable plate fixation with cortical strut graft augmentation

5-         Cable fixation alone

 

PREFERRED RESPONSE: 4

 

DISCUSSION: Type I fractures are trochanteric fractures usually secondary to osteolysis.  Type II fractures are located around the stem.  Type III fractures are distal to the stem.  If the fracture and prosthesis are stable, the fracture can be treated nonsurgically.  If the fracture is unstable, the stability of the prosthesis should be assessed.  If the prosthesis is unstable (type IIB), treatment should consist of revision to a long stem prosthesis that bypasses the fracture by two cortical diameters.  If, as in this patient, the prosthesis is not loose (type IIA), open reduction and internal fixation is the appropriate option.  Proximal femoral allograft is appropriate for type IIIC fractures in which the proximal bone is significantly compromised and the femoral component is loose.

 

REFERENCES: Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 455-492.

Paprosky WG (ed): Revision Total Hip Arthroplasty. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2001, pp 64-69.

 

 

57.      Total hip arthroplasty in a patient with a long-standing hip fusion on the contralateral side is most likely to result in

 

1-         a higher rate of infection.

2-         a higher rate of mechanical failure and loosening.

3-         a higher rate of myositis ossificans.

4-         a higher rate of dislocation.

5-         improved gait efficiency.

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Contralateral total hip arthroplasty in patients with hip fusions results in a 40% higher rate of mechanical failure and loosening.  During gait, motion of the contralateral hip is increased and more time is spent bearing weight on that hip.  In patients with hip fusions, gait efficiency is only 53%, with a greater rate of oxygen consumption.

 

REFERENCES: Garvin KL, Pellicci PM, Windsor RE, et al: Contralateral total hip arthroplasty or ipsilateral total hip arthroplasty in patients who have long-standing fusion of the hip. J Bone Joint Surg Am 1989;71:1355-1362.

Gore DR, Murray MP, et al: Walking patterns of men with unilateral surgical hip fusion. J Bone Joint Surg Am 1975;57:759-765.

Romness DW, Morrey BF: Total knee arthroplasty in patients with prior ipsilateral hip fusion. J Arthroplasty 1992;7:63-70.

 

 

 

58.      A 60-year-old woman reports anterior knee pain 2 years after undergoing primary total knee arthroplasty for rheumatoid arthritis.  A Merchant view of the patella is shown in Figure 16.  What is the most likely cause of her pain?

 

1-         Elevation of the joint line

2-         Lateral placement of the femoral component

3-         Medial placement of the patellar component

4-         Internal rotation of the femoral component

5-         External rotation of the tibial component

 

PREFERRED RESPONSE: 4

 

DISCUSSION: Patellar complications commonly occur after primary total knee arthroplasty; therefore, proper component positioning is critical in obtaining a successful result.  This patient has lateral tilting and subluxation of the patellar component.  Internal rotation of the femoral component has the most deleterious effect on patellar tracking.  Lateral placement of the femoral component, medial placement of the patellar component, and external rotation of the tibial component have beneficial effects on patellar tracking.  Elevation of the joint line, if not excessive, should not impact patellar tracking.

 

REFERENCES: Rand JA: Patellar resurfacing in total knee arthroplasty. Clin Orthop 1990;260:110-117.

Healy WL, Wasliewski SA, Takei R, Oberlander M: Patellofemoral complications following total knee arthroplasty:. Correlation with implant design and patient risk factors. J Arthroplasty 1995;10:197-201.

 

 

 

59.      The anterior portal of a hip arthroscopy places what structure at greatest risk for injury?

 

1-         Ascending branch of the lateral circumflex femoral artery

2-         Ascending branch of the medial circumflex femoral artery

3-         Femoral nerve

4-         Lateral femoral cutaneous nerve

5-         Superior gluteal nerve

 

PREFERRED RESPONSE: 4

 

DISCUSSION: The average location of the anterior portal is 6.3 cm distal to the anterior superior iliac spine.  The lateral femoral cutaneous nerve typically has divided into three or more branches at the level of the anterior portal.  The portal usually passes within several millimeters of the most medial branch.  Injury to the nerve can lead to meralgia paresthetica.  The femoral nerve lies an average minimum distance of 3.2 cm from the anterior portal.  The ascending branch of the lateral circumflex artery lies approximately 3.7 cm inferior to the anterior portal.  Neither the ascending branch of the medial circumflex artery nor the superior gluteal nerve are
at risk.

 

REFERENCES: Byrd JWT: Operative Hip Arthroscopy. New York, NY, Thieme Medical Publishers, 1998, pp 83-91.

Arendt EA (ed): Orthopaedic Knowledge Update: Sports Medicine 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 281-289.

 

 

60.      Figure 17 shows the radiograph of an 80-year-old woman who has left groin pain.  She underwent a total hip arthroplasty 15 years ago and has no history of hip dislocation; however, she now reports that the pain results in functional impairment.  Preoperative findings reveal that the component used has been discontinued, the locking mechanism is poor, and there is no replacement polyethylene available from the company.  During surgery, the acetabular component is found to be well fixed, it is in satisfactory position, and adequate access can be obtained through the screw holes in the component to debride the osteolytic cavities.  What is the best course of action for revision?

 

1-         Remove the component and replace it with a “jumbo” cup with bone graft or substitute.

2-         Remove the component and replace it with a bipolar component with bone graft or substitute.

3-         Remove the component and replace it with a support ring with graft or graft substitute and cement a cup into the support ring.

4-         Score the component for improved cement interdigitation and cement a cup into the retained socket with bone graft or substitute.

5-         Use a structural acetabular graft to reconstruct the acetabulum and cement a cup into the structural graft.

 

PREFERRED RESPONSE: 4

 

DISCUSSION: The clinical result in this patient has been good, with no dislocations, suggesting that the components are in reasonably good position.  The radiograph and examination at the time of surgery suggest that the acetabular component is well fixed.  The surrounding bone of the acetabulum is osteopenic and there would most likely be considerable bone loss if the acetabular component is removed.  Access to the osteolytic lesions is possible.  Cementing an acetabular component into the retained socket will cause the least amount of bone loss, shorten the procedure, and most likely result in a functional hip.

 

REFERENCES: Maloney WJ: Socket retention: Staying in place. Orthopedics 2000;23:965-966.

Blaha JD: Well-fixed acetabular component retention or replacement: The whys and the wherefores. J Arthroplasty 2002;17:157-161.

 

 

 

61.      The need for postoperative allogeneic blood transfusions after total hip arthroplasty has been shown to be reduced when using

 

1-         cementless fixation.

2-         suction drains.

3-         general anesthesia.

4-         preoperative erythropoietin injections.

5-         low-molecular-weight heparin.

 

PREFERRED RESPONSE: 4

 

DISCUSSION: In a prospective study, 216 patients were randomized into three groups consisting of low-dose preoperative erythropoietin, high-dose preoperative erythropoietin, and placebo control.  All patients were treated for 4 weeks prior to total hip arthroplasty.  Both the low- and high-dose erythropoietin groups had a significantly lower rate of blood transfusions
(p < 0.001) after surgery.

 

REFERENCES: Waddell JP: Evidence-based orthopedics. J Bone Joint Surg Am 2001;83:788.

Feagan BG, Wang CJ, Kirkley A, et al: Erythropoietin with iron supplementation to prevent allogeneic blood transfusion in total hip joint arthroplasty: A randomized, controlled, trial. Ann Intern Med 2000;133:845-854.

 

 

 

62.      Which of the following is considered a major characteristic of hyaluronate?

 

1-         Artificial compound used in improving joint reactive force friction

2-         Backbone of the proteoglycan aggregate

3-         Made up of chondroitin sulfate and glucosamine

4-         Primarily made up of water molecules in its protein matrix

5-         Key building block of collagen

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Hyaluronate is a naturally occurring compound that is the backbone of the central core of the proteoglycan aggregate.  Cartilage is made of two principal tissue structures.  The connective tissue component includes collagen, which forms the framework for structural strength and elasticity.  The proteoglycan aggregate provides a unique property of water incorporation and friction reduction capabilities.  Hyaluronate forms the base or central core of the aggregate on which a link protein binds a protein core.  Chondroitin sulfate and keratin sulfate are then bound to this protein core, forming the terminal extension of the aggregate.

 

REFERENCES: Callaghan JJ, Dennis DA, Paprosky WA, Rosenberg AG (eds): Orthopedic Knowledge Update: Hip and Knee Reconstruction. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1995, pp 69-78.

Felson DT: Osteoarthritis. Rheum Dis Clin North Am 1990;16:499-512.

Hurd ER: Extraarticular manifestations of rheumatoid arthritis. Semin Arthritis Rheum 1979;8:151-176.

 

 

 

63.      Which of the following is considered an important factor in improved cemented femoral stem survivorship?

 

1-         Precoated stem with methylmethacrylate

2-         Varus stem position

3-         2 to 3 mm of circumferential cement mantle

4-         Dorr C or “stovepipe” femoral anatomy

5-         Sharp angled corners on the femoral stem

 

PREFERRED RESPONSE: 3

 

DISCUSSION: Cement technique, relative stem to canal size and position, stem design, surgical technique, and femoral anatomy are important factors in cemented stem survivorship.  Varus stem position, a wide diaphyseal to metaphyseal ratio (stovepipe femur), thin cement mantles (1 mm or less), and nonrounded femoral stem designs are negative prognostic factors for stem survivorship.  Precoating with methylmethacrylate has not been shown to provide any increased survivorship over nonprecoated stems.  

 

REFERENCES: Noble PC, Collier MB, Maltry JA, Kamaric E, Tullos HS: Pressurization and centalization enhance the quality and reproducibility of cement mantles. Clin Orthop 1998;355:77-89.

Crowninshield RD, Brand RA, Johnston RC, Milroy JC: The effect of femoral stem cross-sectional geometry on cement stresses in total hip reconstruction. Clin Orthop 1980;146:71-77.

Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 417-451.

 

 

 

64.      An acetabular reinforcement cage is most often indicated for which of the following conditions?

 

1-         Contained cavitary defect

2-         Deficient anterior wall

3-         Pelvic discontinuity

4-         Zone 1 osteolysis

5-         Medial wall defect

 

PREFERRED RESPONSE: 3

 

DISCUSSION: An acetabular reinforcement cage is required infrequently except when there is pelvic discontinuity in which there is no posterior column support of the acetabular cup.  A larger cup inserted with cement and morselized bone graft is an effective technique for contained cavitary and anterior wall defects.  Zone 1 osteolysis and a medial wall defect are essentially the same as a contained cavitary defect and can be reconstructed using cementless cups.

 

REFERENCES: Berry DJ, Lewallen DG, Hanssen A, Cabanela ME: Pelvic discontinuity in revision total hip arthroplasty. J Bone Joint Surg Am 1999;81:1692-1702.

Whaley AL, Berry DJ: Extra-large uncemented hemisphere acetabular components for revision THA. J Bone Joint Surg Am 2001;83:1352-1357.

 

 

 

65.      What is the most common short-term complication following femoral impaction grafting for revision total hip arthroplasty?

 

1-         Periprosthetic fracture

2-         Infection

3-         Loosening

4-         Osteolysis

5-         Dislocation

 

PREFERRED RESPONSE: 1

 

DISCUSSION: Impaction grafting is an alternative for severe femoral bone deficiency; however, stem subsidence is commonly observed during the first few months.  Slight subsidence is felt to be integral to the success of the procedure.  Predictable bone graft incorporation and stable stem fixation have been reported in the medium-term.  The incidence of periprosthetic fractures has been reported as high as 24%.

 

REFERENCES: Mikhail MWE, Weidenhielm L, Jazrawi LM, et al: Collarless, polished, tapered stem failure. J Bone Joint Surg Am 2000;82:1513-1514.

Leopold SS, Rosenberg AG: Current status of impaction allografting for revision of a femoral component. Instr Course Lect 2000;49:111-118.

 

 

 

66.      Which of the following is considered the most predictive factor in determining whether a patient will need a blood transfusion after total knee arthroplasty?

 

1-         Patient’s weight

2-         Gender

3-         Preoperative hemoglobin level

4-         Duration of surgery

5-         Number of medical comorbidities

 

PREFERRED RESPONSE: 3

 

DISCUSSION: Multiple studies have shown that the preoperative hemoglobin level is the most predictive factor in determining whether a transfusion will be necessary after total hip or total knee arthroplasty.  Studies have not shown any correlation with the other options.

 

REFERENCES: Salido JA, Marin LA, Gomez LA, Zorrilla P, Martinez C: Preoperative hemoglobin levels and the need for transfusion after prosthetic hip and knee surgery: Analysis of predictive factors. J Bone Joint Surg Am 2002;84:216-220.

Sculco TP, Gallina J: Blood management experience: Relationship between autologous blood donation and transfusion in orthopedic surgery. Orthopedics 1999;22:S129-S134.

Faris PM, Spence RK, Larholt KM, Sampson AR, Frei D: The predictive power of baseline hemoglobin for transfusion risk in surgery patients. Orthopedics 1999;22:S135-S140.

 

 

67.      A 32-year-old man has posttraumatic arthritis after undergoing open reduction and internal fixation of a left acetabular fracture.  A total hip arthroplasty is performed, and the radiograph is shown in Figure 18.  What is the most common mode of failure leading to revision in this group of patients?

 

1-         Infection

2-         Heterotopic ossification

3-         Dislocation

4-         Periprosthetic fracture

5-         Acetabular component loosening

 

PREFERRED RESPONSE: 5

 

DISCUSSION: Acetabular component loosening has been reported as the most common mode of failure following total hip arthroplasty in patients with a previous acetabular fracture.  Following acetabular fracture and subsequent open reduction and internal fixation, the bone quality and vascularity are compromised, thus reducing the success rate of acetabular component cementless fixation.

 

REFERENCES: Jimenez ML, Tile M, Schenk RS: Total hip replacement after acetabular fracture. Orthop Clin 1997;28:435-446.

Romness DW, Lewallen DG: Total hip arthroplasty after fracture of the acetabulum: Long-term results. J Bone Joint Surg Br 1990;72:761-764.

 

 

 

68.      A 42-year-old man sustained the periprosthetic fracture shown in Figures 19a and 19b.  The femoral component is well fixed.  What is the next most appropriate step in management?

 

1-         Closed reduction and bracing

2-         Retrograde femoral intramedullary nailing

3-         Open reduction and internal fixation of the fracture, leaving the femoral stem in place

4-         Open reduction and internal fixation of the fracture and insertion of a proximally porous-coated stem

5-         Open reduction and internal fixation of fracture fragments and insertion of a fully porous-coated femoral stem with diaphyseal fixation distal to the fracture

 

PREFERRED RESPONSE: 3

 

DISCUSSION: The patient has a periprosthetic fracture below the femoral stem.  The component is porous coated and well fixed.  Open reduction and internal fixation, leaving the stem in place, can be performed when bone quality is good.  Plating with or without allograft struts and supplemental cerclage fixation generally is acceptable.  If the component is loose, revision to a longer device is recommended with appropriate stabilization of the fracture using the aforementioned methods.  If bone loss has occurred, allograft supplementation or a tumor prosthesis may be indicated.  Fractures located well below the stem tip can be treated without regard for the prosthesis.  Closed reduction and bracing is not associated with good results for periprosthetic femoral fractures.  Retrograde intramedullary nailing is not appropriate for this fracture.

 

REFERENCES: Duncan CP, Masri BA: Fractures of the femur after hip replacement. Instr Course Lect 1995;44:293-304.

Bono JV, McCarthy JC, Thornhill TS, Bierbaum BE, Turner RH (eds): Revision Total Hip Arthroplasty. New York, NY, Springer Verlag, 1999, pp 530-592.

 

 

 

69.      A 58-year-old man has anterior knee pain after undergoing total knee arthroplasty for osteoarthritis 2 years ago.  He denies any history of trauma.  A Merchant view is shown in Figure 20.  What is the most likely cause of his pain?

 

1-         External rotation of the femoral component

2-         Overstuffing of the patellofemoral joint

3-         Less than 12 mm of bony patella remaining after resection

4-         Lateral retinacular release

5-         Use of a cemented patellar component

 

PREFERRED RESPONSE: 3

 

DISCUSSION: The patient has a patellar stress fracture after resurfacing in a total knee arthroplasty.  Several studies have shown that over-resection of the patella to less than 12 to 15 mm increases anterior patellar surface strains to a point where the risk of fracture is increased.  Increasing the patellar thickness, positioning of the femoral component, lateral releases, and component types have not been clearly associated with increased fracture risk.  

 

REFERENCES: Reuben JD, McDonald CL, Woodard PL, Hennington LJ: Effect of patella thickness on patella strain following total knee arthroplasty. J Arthroplasty 1991;6:251-258.

Hsu HC, Luo ZP, Rand JA, An KN: Influence of patellar thickness on patellar tracking and patellofemoral contact characteristics after total knee arthroplasty. J Arthroplasty 1996;11:69-80.

Greenfield MA, Insall JN, Case GC, Kelly MA: Instrumentation of the patellar osteotomy in total knee arthroplasty: The relationship of patellar thickness and lateral retinacular release. Am J Knee Surg 1996;9:129-131.

 

 

 

70.      A 30-year-old patient has acetabular dysplasia and moderate secondary osteoarthrosis.  Which of the following studies will best help predict the success of periacetabular osteotomy?

 

1-         High-resolution CT with coronal and sagittal reconstructions

2-         Glycosaminoglycan MRI

3-         Functional radiographic or fluoroscopic evaluation

4-         Gadolinium-contrast arthrography with MRI

5-         Routine AP and lateral radiographs

 

PREFERRED RESPONSE: 3

 

DISCUSSION: Improvement in the appearance of the hip joint on functional radiographic evaluation (abduction/adduction views) has been shown to be predictive of outcome following joint preserving surgery.  CT and MRI findings have not been shown to be predictive of outcome. 

 

REFERENCE: Murphy S, Deshmukh R: Periacetabular osteotomy: Preoperative radiographic predictors of outcome. Clin Orthop 2002;405:168-174.

 

 

 

71.       Which of the following is considered a specific advantage of using COX-2 inhibitors over COX-1 inhibitors?

 

1-         Conversion of arachidonic acid to prostaglandins

2-         Higher degree of efficacy

3-         Does not affect platelet function and can be used during the perioperative period

4-         Can be used in patients with congestive heart failure and renal disease

5-         High levels of COX-2 (cyclooxygenase) found in normal tissue

 

PREFERRED RESPONSE: 3

 

DISCUSSION: Inflammation is mediated through two isoforms of cyclooxygenase that convert arachidonic acid to prostaglandins.  Selectivity, but not specificity, is one of the unique characteristics of this process that has been able to provide more protection from the effects of gastric mucosal alterations using the COX-2 selective inhibitors.  The use of COX-1 selective inhibitors is associated with side effects such as ulcerative conditions and platelet interference, both of which have been difficult to control in the past until the advent of the COX-2 inhibitors.  PGE₂ inhibition by COX-1 in the intestinal track can then be bypassed, thereby reducing ulceration complications associated with use of nonsteroidal anti-inflammatory drugs.

 

REFERENCES: Lane JM: Anti-inflammatory medications: Selective COX-2 inhibitors. J Am Acad Orthop Surg 2002;10:75-78.

Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002.

Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000.

 

 

72.      Which of the following is not a reported mode of failure for a constrained acetabular component?

 

1-         Loosening of the acetabular component

2-         Disengagement of the constraining ring (with or without redislocation)

3-         Increased abrasive (polyethylene) wear

4-         Dissociation of the femoral head from the neck

5-         Dissociation of the polyethylene liner from the acetabular shell

 

PREFERRED RESPONSE: 3

 

DISCUSSION: There is no evidence of increased polyethylene wear in constrained acetabular components.  The rates of wear appear to be the same using standard or constrained liners.

 

REFERENCES: Lachiewicz PF, Kelley SS: Constrained components in total hip arthroplasty. J Am Acad Orthop Surg 2002;10:233-238.

Anderson MJ, Murray WR, Skinner HB: Constrained acetabular components. J Arthroplasty 1994;9:17-23.

Fisher DA, Kiley K: Constrained acetabular cup disassembly. J Arthroplasty 1994;9:325-329.

 

 

73.      Which of the following factors is most likely to be associated with prolonged survival of total knee arthroplasty?

 

1-         History of high tibial osteotomy

2-         Diagnosis of traumatic arthritis

3-         Diagnosis of rheumatoid arthritis

4-         Diagnosis of osteoporosis

5-         Diagnosis of osteonecrosis

 

PREFERRED RESPONSE: 3

 

DISCUSSION: In a survivorship study of 9,200 total knee arthroplasties, Rand and Ilstrup identified four independent variables associated with a significantly lower risk of failure: primary total knee arthroplasty, diagnosis of rheumatoid arthritis, age of 60 years or older, and use of a condylar prosthesis with a metal-backed tibial component.  Other clinical studies report the use of a posterior stabilized prosthesis to be comparable to a total condylar prosthesis with retained posterior cruciate ligament.

 

REFERENCES: Rand JA, Ilstrup DM: Survivorship analysis of total knee arthroplasty: Cumulative rates of survival of 9200 total knee arthroplasties. J Bone Joint Surg Am 1991;73:397-409.

Stern SH, Insall JN: Posterior stabilized prosthesis: Results after follow-up of nine to twelve years. J Bone Joint Surg Am 1992;74:980-986.

Knutson K, Lindstrand A, Lidgren L: Survival of knee arthroplasties: A nation-wide multicentre investigation of 8000 cases. J Bone Joint Surg Br 1986;68:795-803.

 

 

74.      Analysis of primary total hip arthroplasty using press-fit acetabular components without supplementary screw fixation reveals that screw fixation

 

1-         increases backside polyethylene wear.

2-         decreases the incidence of persistent radiolucent lines.

3-         decreases the incidence of cup malposition.

4-         increases the incidence of early cup migration.

5-         increases the percentage of satisfactory results.

 

PREFERRED RESPONSE: 1

 

DISCUSSION: Using mechanical failure of fixation as the end point, Udomkiat and associates demonstrated a 12-year survivorship of 99.1% for titanium press-fit acetabular components without supplementary screw fixation.  This study suggests that it is unlikely that the use of supplementary screws would lead to improved results.  In addition, polyethylene wear debris tends to migrate through screw holes and along the course of screws.  Screw holes also decrease the available surface for bone ingrowth.  Screws that back up may be a source of backside polyethylene wear.  This suggests that screw holes and the use of screws should be avoided when they are unnecessary for cup fixation. 

 

REFERENCE: Udomkiat P, Dorr LD, Wan Z: Cementless hemispheric porous-coated sockets implanted with press-fit technique without screws: Average ten-year follow-up. J Bone Joint Surg Am 2002;84:1195-1200. 

 

 

 

 

75.      Dislocation following primary total hip arthroplasty is more likely to occur in which of the following situations?

 

1-         Women rather than men

2-         Younger patients rather than older patients

3-         Ceramic-on-polyethylene bearings rather than cobalt-chromium on polyethylene bearings

4-         Cemented rather than cementless femoral components

5-         Metal-on-polyethylene rather than metal-on-metal bearings of the same diameter

 

PREFERRED RESPONSE: 1

 

DISCUSSION: Dislocation following total hip arthroplasty is twice as common in women than in men.  It is more likely to occur in older patients.  There is no clear association between dislocation and the method of fixation or the type of bearing, so long as the bearing diameter is the same.  

 

REFERENCE: Berry DJ: Dislocation, in Steinberg ME (ed): Revision Total Hip Arthroplasty.  Philadelphia, PA, 1999, pp 463-482.

 

 

 

76.      What is the average linear wear rate of a conventional, noncross-linked ultra-high molecular weight polyethylene liner used in total hip arthroplasty?

 

1-         0.01 to 0.05 mm/yr

2-         0.1 to 0.2 mm/yr

3-         0.5 to 1 mm/yr

4-         1 to 2 mm/yr

5-         Greater than 2 mm/yr

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Several studies have shown that ultra-high molecular weight polyethylene liners used in total hip arthroplasties wear at a rate of 0.1 to 0.2 mm/yr.  The orthopaedic surgeon performing total hip arthroplasties should be aware of the average wear rate so that potential problems can be identified when following patients postoperatively.

 

REFERENCES: Callaghan JJ, Albright JC, Goetz DD, Olejniczak JP, Johnston RC: Charnley total hip arthroplasty with cement: Minimum twenty-five year follow-up. J Bone Joint Surg Am 2000;82:487-497.

Isaac GH, Wroblewski BM, Atkinson JR, Dowson D: A tribological study of retrieved hip prostheses. Clin Orthop 1992;276:115-125.

 

 

 

77.       A 68-year-old woman underwent a successful total right hip arthroplasty with a
metal-on-metal articulation and cementless porous-coated components.  Three months later, she underwent identical surgery on the left hip.  Three months after surgery on the left hip, she reports groin pain on ambulation.  Examination reveals significant groin discomfort with passive hip motion, particularly at the extremes of motion.  Radiographs are shown in Figures 21a and 21b.  Laboratory studies show an erythrocyte sedimentation rate of 35 mm/h and a C-reactive protein of 0.9.  Aspiration yields scant growth of Staphylococcus epidermidis in the broth only, with no evidence of loosening on arthrography.  A second aspiration yields scant growth of Staphylococcus epidermidis in the broth only.  What is the most likely cause of the patient’s pain?

 

1-         Allergic metal synovitis

2-         Aseptic loosening of the acetabular component

3-         Septic loosening of the acetabulum

4-         Deconditioning following hip arthroplasty

5-         Iliopsoas tendinitis

 

PREFERRED RESPONSE: 3

 

DISCUSSION: The difference in the clinical results combined with the laboratory findings points to infection.  While there is a significant risk of false-positive findings with aspiration, the fact that two successive aspirations grew the same organism strongly suggests infection.  The radiograph shows that there is more radiolucency around the left acetabular component than the right component.

 

REFERENCES: White RE: Evaluation of the painful total hip arthroplasty, in Callaghan JJ, Rosenberg AG, Rubash HE (eds): The Adult Hip. Philadelphia, PA, Lippincott-Raven, 1998,
vol 2, pp 1377-1385.

Barrack RL, Harris WH: The value of aspiration of the hip joint before revision total hip arthroplasty. J Bone Joint Surg Am 1993;75:66-76.

 

 

 

78.      Etanercept is a recombinant genetically engineered fusion protein used to treat rheumatoid arthritis.  What is its mode of action?

 

1-         Monoclonal antibody that binds TNF-α

2-         Blocks the binding of IL-1 to receptors

3-         Soluble receptor that binds TNF-α

4-         Soluble factor that binds rheumatoid factor

5-         Directly inhibits pyrimidine synthesis

 

PREFERRED RESPONSE: 3

 

DISCUSSION: Etanercept is a molecule consisting of the Fc portion of IgG fused to the extracellular domain of the p76 human THF-α receptor.  It is soluble and binds TNF-α.  Infliximab is the monoclonal antibody that binds TNF-α.  IL-1 receptor antagonists are still in development.  Leflunomide is a drug that inhibits pyrimidine synthesis and is similar to methotrexate as an antimetabolite.

 

REFERENCE: Koval KJ (ed): Orthopaedic Knowlegde Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 193-199.

 

 

 

79.      Which of the following bearing materials is most resistant to scratching from third-body debris?

 

1-         Alumina

2-         Stainless steel

3-         Forged cobalt-chromium

4-         Ion bombarded and forged cobalt-chromium

5-         Oxidized titanium

 

PREFERRED RESPONSE: 1

 

DISCUSSION: Alumina is the hardest of all the materials listed.  Clinical retrieval demonstrates resistance to scratching from third-body debris.

 

REFERENCE: Cooper JR, Dowson D, Fisher J, Jobbins B: Ceramic bearing surfaces in total articular joints: Resistance to third body damage from bone cement particles. J Med Eng Technol 1991;15:63-67.

 

80.      Which of the following surgical techniques is associated with an  increased incidence of patellar complications after total knee arthroplasty?

 

1-         Medialization of the patellar component

2-         Symmetric patellar osteotomy

3-         Use of metal-backed patellar components

4-         Maintaining a patellar thickness of 12 to 15 mm

5-         External rotation of the femoral component

 

PREFERRED RESPONSE: 3

 

DISCUSSION: Surgical technique in patellar resurfacing has been found to be one of the critical factors in the success or failure of total knee arthroplasty.  Theoretically, metal-backed patellar components are an excellent way of evenly distributing joint forces from the polyethylene button to bone (similar to the tibial component).  However, despite this theoretical advantage, metal-backed patellae have been associated with a higher failure rate.  Some of the observed problems include poor bone ingrowth, peg failure, dissociation of the metal plate and polyethylene button, and component fracture.  Because of these factors, all-polyethylene patellae have proved to be the standard if patellar resurfacing is attempted.  Medialization of the patellar component, a symmetrically thick patella, and external rotation of the femoral and tibial components improve patellar tracking.

 

REFERENCES: Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 323-337.

Barrack RL, et al: Resurfacing of the patella in total knee arthroplasty: A prospective, randomized, double-blind study. J Bone Joint Surg Am 1997;79:1121-1131.

 

 

81.       A large circumferential proximal femoral allograft is to be used in the reconstruction of a failed femoral component in a total hip arthroplasty.  To enhance fixation of the graft to the implant, which of the following strategies should be used?

 

1-         Modern cement technique

2-         Porous-coated stem

3-         Nonporous press-fit stem

4-         Hydroxyapatite-coated stem

5-         Cerclage wire fixation

 

PREFERRED RESPONSE: 1

 

DISCUSSION: The optimum treatment is cementing the implant to the allograft.  Press-fit stability is unreliable. Wires and screws may be used for an incomplete proximal femoral allograft but cannot be used to anchor a complete proximal femoral allograft.

 

REFERENCES: Allan DG, Lavoie GJ, Rudan JF, et al: The use of allograft bone in revision total hip arthroplasty, in Friedlaender GE, Goldberg VM (eds): Bone and Cartilage Allografts: Biology and Clinical Applications. Park Ridge, IL, American Academy of Orthopaedic Surgeons, 1991, pp 263-264.

Gross AE, Lavoie MV, McDermott P, Marks P: The use of allograft bone in revision of total hip arthroplasty. Clin Orthop 1985;197:115-122.

Head WC, Berklacich FM, Malinin TI, Emerson RH Jr: Proximal femoral allografts in revision total hip arthroplasty. Clin Orthop 1987;225:22-36.

 

 

 

82.      Which of the following design features of a femoral component used in a total knee arthroplasty best minimizes the patellar component contact stresses?

 

1-         Shallow, flat anatomic femoral trochlear groove 

2-         Deep, curved anatomic femoral trochlear groove 

3-         Narrow femoral trochlear groove

4-         Universal trochlear groove (same for right and left)

5-         Thickened anterior flange

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Several studies have shown that design of the femoral component, especially the trochlear groove portion, largely influences patellar tracking and patellofemoral contact stresses.  A deep, curved anatomic femoral trochlear groove has been shown to have the lowest contact stresses. 

 

REFERENCES: Petersilge WJ, Oishi CS, Kaufman KR, Irby SE, Colwell CW Jr: The effect of trochlear design on patellofemoral shear and compressive forces in total knee arthroplasty. Clin Orthop 1994;309:124-130.

Theiss SM, Kitziger KJ, Lotke PS, Lotke PA: Component design affecting patellofemoral complications after total knee arthroplasty. Clin Orthop 1996;326:183-187.

Healy WL, Wasliewski SA, Takei R, Oberlander M: Patellofemoral complications following total knee arthroplasty:. Correlation with implant design and patient risk factors. J Arthroplasty 1995;10:197-201.

 

 

83.      Figure 22 shows the radiograph of a 67-year-old woman who has an infected left total hip arthroplasty.  The most efficient means to remove the distal cement mantle includes the use of

 

1-         controlled perforation.

2-         cortical bone window.

3-         fluoroscopically guided instrumentation.

4-         extended trochanteric osteotomy.

5-         transtrochanteric osteotomy.

 

PREFERRED RESPONSE: 4

 

DISCUSSION: An extended trochanteric osteotomy has been shown to be very efficient in removing a well-fixed distal implant and cement with minimal complications.  Direct lateral, posterior, and transtrochanteric osteotomy exposures do not provide exposure of the midfemur.

 

REFERENCE: Younger T, Bradford M, Magnus R: Extended proximal femoral osteotomy: A new technique for femoral revision arthroplasty. J Arthroplasty 1995;10:329-338.

 

 

84.      Which of the following findings best describes the effects of increasing conformity of a fixed tibial bearing component and femoral component in total knee arthroplasty?

 

1-         Increased peak contact stress, decreased component edge loading

2-         Increased peak contact stress, increased component wear rates

3-         Decreased peak contact stress, increased component wear rates

4-         Decreased peak contact stress, decreased component wear rates

5-         Decreased peak contact stress, decreased component edge loading

 

PREFERRED RESPONSE: 4

 

DISCUSSION: In the design of tibial and femoral components, a compromise must be made between contact stresses and constraint.  Increased conformity increases constraint, limits motion, and potentially increases stress on the knee-cement interface.  By increasing conformity, the surface area over which force is applied is increased, resulting in decreased peak contact stresses and decreased component wear rates.

 

REFERENCES: Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 265-274.

Bartel DL, Rawlinson JJ, Burstein AH, Ranawat CS, Flynn WF Jr: Stresses in polyethylene components of contemporary total knee replacements. Clin Orthop 1995;317:76-82.

 

 

 

85.      Figures 23a and 23b show the AP and lateral radiographs of a 67-year-old woman who has severe left knee pain when ambulating.  History reveals that she underwent primary total knee arthroplasty 7 years ago.  The patient reports increasing deformity over the past several years and uses a knee brace and a cane.  Examination reveals that she walks with a varus thrust and has an uncorrectable varus deformity with valgus force.  What is the primary reason for implant failure?

 

1-         Osteolysis

2-         Polyethylene wear

3-         Tibial component fixation failure

4-         Modular tibial component failure

5-         Posterior cruciate ligament retention

 

PREFERRED RESPONSE: 3

 

DISCUSSION: Both cemented and cementless total knee arthroplasties depend on adequate fixation of the tibial component to promote long-term survivorship.  An effective stem and adequate peripheral fixation of the tibial component to the cancellous-cortical portion of the proximal tibia are necessary for cementless fixation.  Peripheral screws and pegs can serve as adjunctive fixation to decrease micromotion and shear forces and allow bone ingrowth to occur.  Careful preparation of the proximal tibial surface can minimize fixation failure.  Cemented fixation of the tibial stem should be performed in addition to the plateau.  Osteolysis, polyethylene wear, and failure at the insert/tray locking mechanism have not occurred.  Posterior cruciate ligament retention has not caused the tibial component fixation failure. 

 

REFERENCE: Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 275-279.

 

 

 

86.      Which of the following bearing surface combinations has shown the lowest in vivo wear rates in total hip arthroplasty?

 

1-         Cobalt-chromium alloy femoral head-on-cobalt-chromium alloy socket

2-         Cobalt-chromium alloy femoral head-on-polyethylene socket

3-         Titanium femoral head-on-polyethylene socket

4-         Ceramic femoral head-on-ceramic socket

5-         Ceramic femoral head-on-polyethylene socket

 

PREFERRED RESPONSE: 4

 

DISCUSSION: Ceramic bearings, made of alumina, have the lowest in vivo wear rates of any bearing combination, 0.5 to 2.5 µ per component per year.  Laboratory wear rates for metal-on-metal are lower than those for metal-on-polyethylene bearings, ranging from 2.5 to 5.0 µ per year.  Titanium used for bearing surfaces has a high failure rate because of a poor resistance to wear and notch sensitivity.  Wear rates for ceramic-on-polyethylene bearings have varied, ranging from 0 to 150 µ.

 

REFERENCES: Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 47-53. 

Jazrawi LM, Kummer FJ, DiCesare PE: Alternative bearing surfaces for total joint arthroplasty. J Am Acad Orthop Surg 1998;6:198-203.

 

 

 

87.      Figure 24 shows the radiograph of a 47-year-old woman who has severe right hip pain and a limp.  Management should consist of

 

1-         acetabular osteotomy.

2-         femoral and acetabular osteotomy.

3-         total hip arthroplasty using standard trochanter osteotomy and cementless components.

4-         total hip arthroplasty using femoral shortening osteotomy and cementless components.

5-         total hip arthroplasty using femoral shortening osteotomy, a cemented socket, and a cementless femoral component.

 

PREFERRED RESPONSE: 4

 

DISCUSSION: Femoral shortening osteotomy for a Crowe type IV hip dislocation has been shown to provide superior results with minimal complications.  Cementless fixation of the stem allows for modular implants that greatly simplify the reconstruction.

 

REFERENCE: Jaroszynski G, Woodgate IG, Saleh KJ, Gross AE: Total hip replacement for the dislocated hip. Instr Course Lect 2001;50:307-316.

 

 

 

88.      When planning revision of a total hip arthroplasty where an acetabular reconstruction will be required, what prerequisite is important to ensure long-term success of a cementless component?

 

1-         Absence of acetabular protrusio

2-         Presence of posterior column

3-         Presence of anterior column

4-         Presence of at least 50% host bone

5-         Presence of a segmental defect

 

PREFERRED RESPONSE: 4

 

DISCUSSION: In bone defects where host bone support is less than 50%, the failure rate is 70% at 5.1 years.  The presence or absence of columns or hip position is of relatively little importance if the supportive bone is not present in at least 50% of the surface area around the future acetabular implant.

 

REFERENCE: Gross AE, Allan DG, Catre M, et al: Bone grafts in hip replacement surgery: The pelvic side. Orthop Clin North Am 1993;24:679-695.

 

89.      A 62-year-old man who underwent total knee arthroplasty 6 months ago now reports pain after falling on the anterior portion of the knee.  Examination reveals weakness of knee extension but no extensor lag.  Flexion that had once measured 115 degrees is now limited to 70 degrees because of pain.  A radiograph is shown in Figure 25.  Management should now consist of

 

1-         immediate repair of the ruptured patellar tendon insertion.

2-         knee joint aspiration and injection of a local anesthetic to facilitate examination.

3-         joint aspiration for culture, broad-spectrum antibiotics, and immobilization.

4-         immobilization until comfortable, followed by protected range of motion and strengthening.

5-         immediate fracture repair.

 

PREFERRED RESPONSE: 4

 

DISCUSSION: The patient has a type IIIB patellar fracture (inferior pole fracture with an intact patellar tendon).  Nonsurgical management is the treatment of choice if there is little displacement and the extensor mechanism is intact.

 

REFERENCES: Brown TE, Diduch DR: Fractures of the patella, in Insall JN, Scott WN (eds): Surgery of the Knee, ed 3. Philadelphia, PA, Churchill Livingstone, 2001, vol 2, pp 1290-1312.

Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000,
pp 323-337.

 

 

 

90.      Failure of high tibial osteotomy (HTO) is most closely associated with which of the following factors?

 

1-         Patient age of less than 50 years at the time of surgery

2-         Stable fixaton of the osteotomy

3-         Development of deep venous thrombosis postoperatively

4-         Type of osteotomy performed (ie, opening wedge versus dome osteotomy)

5-         Presence of a lateral tibial thrust preoperatively

 

PREFERRED RESPONSE: 5

 

DISCUSSION: Long-term survivorship studies have attempted to clarify patient factors related to good outcomes in HTO.  One particular study showed that a patient age of less than 50 years was related to good outcomes in those who had good preoperative knee flexion.  The same study found no relation between HTO failure and the presence of postoperative infection or deep venous thrombosis.  The presence of a lateral tibial thrust is a contraindication to performing this surgery.  As expected, good patient selection is critical to obtaining good long-term results
with HTO.

 

REFERENCES: Naudie D, Borne RB, Rorabeck CH, Bourne TJ: Survivorship of the high tibial valgus osteotomy: A 10- to 22-year followup study. Clin Orthop 1999;367:18-27.

Rinonapoli E, Mancini GB, Corvaglia A, Musiello S: Tibial osteotomy for varus gonarthrosis: A 10- to 21-year followup study. Clin Orthop 1998;353:185-193.

Coventry MB, Ilstrup DM, Wallrichs SL: Proximal tibial osteotomy: A critical long-term study of eighty-seven cases. J Bone Joint Surg Am 1993;75:196-201.

 

 

91.      During a posterior cruciate ligament-sacrificing total knee arthroplasty with anterior referencing, 8 mm of distal femur is resected.  It is noted that the flexion gap is tight and the extension gap appears stable.  What is the next most appropriate step in management?

 

1-         Cut more proximal tibia.

2-         Cut more distal femur.

3-         Cut both the proximal tibia and distal femur.

4-         Decrease the size of the femoral component.

5-         Decrease the tibial polyethylene insert thickness.

 

PREFERRED RESPONSE: 4

 

DISCUSSION: If the flexion gap is tight and the extension gap is correct, it is preferable to change only the flexion gap and leave the extension gap unchanged; therefore, the treatment of choice is to decrease the size of the femoral component.  The smaller component will be smaller in both medial-lateral as well as anterior-posterior dimensions.  A smaller anterior-posterior size will allow more space for the flexion gap without significantly affecting the extension gap.  Decreasing the size of the tibial polyethylene insert thickness or cutting more proximal tibia will affect both the flexion and extension gaps.  Cutting more distal femur will increase the extension gap and not change the flexion gap, making the described situation worse.  Cutting both the proximal tibia and distal femur will increase both the flexion and extension gaps.

 

REFERENCE: Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 281-286, 339-365.

 

 

92.      A 72-year-old woman with rheumatoid arthritis who underwent primary total knee arthroplasty 2 years ago has had diffuse knee pain that developed shortly after the surgery.  The patient has difficulty with stair descent and arising from chairs.  Evaluation for infection is negative.  AP and lateral radiographs are shown in Figure 26.  Management should now consist of

 

1-         anti-inflammatory drugs.

2-         a knee brace.

3-         physical therapy for quadriceps strengthening.

4-         revision to a thicker polyethylene insert.

5-         revision to a posterior stabilized implant.

 

PREFERRED RESPONSE: 5

 

DISCUSSION: The radiographs show posterior flexion instability that is the result of flexion-extension gap imbalance and/or posterior cruciate ligament incompetence after a posterior cruciate-retaining total knee arthroplasty.  The radiographs also show anterior femoral displacement on the tibia.  Pagnano and associates reported on a series of patients with painful total knee arthroplasties who had been previously diagnosed as having pain of unknown etiology, showing that the pain was secondary to flexion instability.  Pain relief was achieved by revision to a posterior stabilized implant.

 

REFERENCES: Pagnano MW, Hanssen AD, Lewallen DG, Stuart MJ: Flexion instability after primary posterior cruciate retaining total knee arthroplasty. Clin Orthop 1998;356:39-46.

Fehring TK, Valadie AL: Knee instability after total knee arthroplasty. Clin Orthop 1994;299:157-162.

Fehring TK, Odum S, Griffin WL, Mason B, Nadaud M: Early failures of total knee arthroplasty. Clin Orthop 2001;392:315-318.

 

 

93.      A homebound 75-year-old woman with diabetes mellitus has had progressive left knee pain and swelling for the past 6 weeks.  She is febrile with a temperature of 103 degrees F (39.5 degrees C).  History reveals that she underwent arthroplasty 5 years ago.  Examination shows passive range of motion of 0 to 100 degrees with no active extension.  Knee aspiration reveals purulent fluid with a Gram stain showing gram-negative rods.  A radiograph is shown in Figure 27.  In addition to IV antibiotics, which of the following management options offers the best chance of a successful outcome?

 

1-         Incision and drainage with repair of the extensor mechanism

2-         Removal of components and delayed revision knee arthroplasty with an allograft extensor mechanism

3-         Removal of components and immediate exchange revision total knee arthroplasty

4-         Removal of components and delayed knee arthrodesis

5-         Removal of components and delayed revision knee arthroplasty with extensor mechanism repair

 

PREFERRED RESPONSE: 4

 

DISCUSSION: The patient has an infected total knee arthroplasty and an interrupted extensor mechanism.  A late infection of a total knee arthroplasty in a patient with diabetes mellitus and a virulent organism requires removal of the components, debridement, antibiotic spacers, and surveillance to ensure eradication of the infection.  Reconstruction of an incompetent extensor mechanism in an infected knee is extremely unlikely to be successful.  Arthrodesis is the procedure of choice if a revision total knee arthroplasty is not likely to succeed.  Resection arthroplasty is recommended only as a long-term solution if the patient is medically unable to undergo further surgery.

 

REFERENCES: Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgery, 2002, pp 513-536.

Hanssen AD, Rand JA: Evaluation and treatment of infection at the site of a total hip or knee arthroplasty. Instr Course Lect 1999;48:111-122.

 

 

94.      Design and manufacturing of a metal-on-metal articulation has an important influence on the tribology.  Which of the following statements best characterizes the type of contact that is best for metal-on-metal articulations?

 

1-         Equatorial contact should exceed polar contact.

2-         Polar contact should exceed equatorial contact.

3-         Polar and equatorial contact should be equal by exactly duplicating radii.

4-         The “bedding in” process makes consideration of polar equatorial contact unimportant.

5-         The stiffness of metal-on-metal articulations makes consideration of polar equatorial contact unimportant.

 

PREFERRED RESPONSE: 2

 

DISCUSSION: It is important that the radii of a metal-on-metal head to cup articulation be such that there is polar contact.  As the radii become closer to equal, conditions favor higher frictional torque and equatorial seizing.  The “bedding in” of metal-on-metal surfaces and their stiffness are both components of the properties considered in the design of polar contact surfaces.

 

REFERENCE: Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 25-34.

 

 

 

95.      A 52-year-old man has had groin and deep buttock pain for the past 2 months.  Examination reveals that hip range of motion is mildly restricted, and he has pain with both weight bearing and at rest.  An MRI scan is shown in Figure 28.  Management should consist of

 

1-         protected weight bearing and anti-inflammatory drugs.

2-         core decompression of the femoral head.

3-         vascularized free fibular grafting to the femoral head.

4-         bipolar hemiarthroplasty of the hip.

5-         total hip arthroplasty.

 

PREFERRED RESPONSE: 1

 

DISCUSSION: The MRI findings show highly increased signal through the entire femoral head and neck that is diagnostic of transient osteoporosis of the femoral head.  This recently described entity is often seen in middle-aged men and should be treated nonsurgically with protected weight bearing and anti-inflammatory drugs.  The natural history is that of self-resolution.

 

REFERENCES: Guerra JJ, Steinberg ME: Distinguishing transient osteoporosis from avascular necrosis of the hip. J Bone Joint Surg Am 1995;77:616-624.

Urbanski SR, de Lange EE, Eschenroeder HC Jr: Magnetic resonance imaging of transient osteoporosis of the hip:. A case report. J Bone Joint Surg Am 1991;73:451-455.

 

 

96.      Polyethylene wear of the bearing surface has been recognized as a mode of failure in total knee arthroplasty; therefore, many patients are offered polyethylene exchange.  In terms of success rates, this surgical procedure has been reported to have a

 

1-         rate of less than 50%, primarily the result of infection.

2-         rate of greater than 50%.

3-         lower rate in patients in which metallosis was identified.

4-         similar rate with or without preoperative osteolysis.

5-         similar rate regardless of the degree of wear.

 

PREFERRED RESPONSE: 4

 

DISCUSSION: Engh and associates reported on the results of 63 knees (56 patients) following polyethylene exchange.  The mean interval between exchange and the index total knee arthroplasty was 59 months.  The mean follow-up after exchange was 7.4 years.  Seven of 48 knees with adequate follow-up failed.  Greater failure occurred if there was more severe wear before the exchange.  Greater undersurface wear also resulted in a higher failure rate.  Perioperative osteolysis or intraoperative observation of metallosis did not have an impact on the failure of polyethylene exchange.  The risk of infection is no different from other total knee arthroplasty revisions.

 

REFERENCES: Wasielewski RC, Parks N, Williams I, et al: Tibial insert undersurface as a contributing source of polyethylene wear debris. Clin Orthop 1997;345:53-59.

Engh GA, Koralewicz LM, Pereles TR: Clinical results of modular polyethylene insert exchange with retention of total knee arthroplasty components. J Bone Joint Surg Am 2000;82:516-523.

 

 

 

97.      Which of the following types of ultra-high molecular weight polyethylene has been associated with the poorest clinical performance?

 

1-         Compression molded

2-         Heat pressed

3-         Ram extruded

4-         Gamma irradiated

5-         Ethylene oxide sterilized

 

PREFERRED RESPONSE: 2

 

DISCUSSION: Numerous studies have documented the poor performance of heat-pressed ultra-high molecular weight polyethylene used in the porous-coated anatomic tibial inserts of both total knee and unicompartmental arthroplasty.  The other processing and sterilization methods have not been associated with significantly high failure rates.

 

REFERENCES: Wright TM, Rimnac CM, Stulberg SD, et al: Wear of polyethylene in total joint replacements: Observations from retrieved PCA knee implants. Clin Orthop 1992;276:126-134.

Landy MM, Walker PS: Wear of ultra-high molecular-weight polyethylene components of 90 retrieved knee prostheses. J Arthroplasty 1988;3:S73-S85.

Skyrme AD, Mencia MM, Skinner PW: Early failure of the porous-coated anatomic cemented unicompartmental knee arthroplasty: . A 5- to 9-year follow-up study. J Arthroplasty 2002;17:201-205.

 

 

98.      Which of the following is considered the best method for the prevention of wrong-site surgery?

 

1-         The surgeon should check the consent form for the site and the procedure to be performed.

2-         The surgeon should ask the circulating nurse in the operating room.

3-         The patient should write “yes” on the surgical site at home with a permanent marker.

4-         The surgeon should initial the surgical site after discussion with the patient.

5-         The surgeon should check the operating room schedule.   

 

PREFERRED RESPONSE: 4

 

DISCUSSION: The best method of preventing wrong-site surgery is for the surgeon to initial the surgical site in the preoperative holding area after discussion and confirmation of the site with the patient.  This should be done before sedating medications are administered.  A recent study found that patient noncompliance with specific preoperative instructions to mark the site with a “yes” at home was surprisingly high; only 59% of the patients marked the extremity correctly and 37% made no mark.  Noncompliance was higher in those with workers’ compensation claims (70%) and those with previous related surgery (51%).

 

REFERENCES: DeGiovanni CW, Kang L, Manuel J: Patient compliance in avoiding wrong site surgery. J Bone Joint Surg Am 2003;85:815-819.

American Academy of Orthopaedic Surgeons. Advisory Statement: Wrong-site Surgery. Document 1015, 2002 Sept. www.aaos.org/wordhtml/papers/advismt/wrong.htm.

 

 

99.      During the implantation of a cementless acetabular component in total hip arthroplasty, placement of a screw in the anterior superior quadrant puts which of the following structures at risk for damage?

 

1-         Sciatic nerve

2-         Internal iliac vessels

3-         External iliac vessels

4-         Femoral vessels

5-         Obturator vessels

 

PREFERRED RESPONSE: 3

 

DISCUSSION: A knowledge of the safe quadrants for screw placement for acetabular component implantation is essential when performing total hip arthroplasty.  The external iliac vessels are on the inner wall of the pelvis, corresponding to the anterior superior quadrant of the acetabulum.

 

REFERENCES: Keating EM, Ritter MA, Faris PM: Structures at risk from medially placed acetabular screws. J Bone Joint Surg Am 1990;72:509-511.

Wasielewski RC, Cooperstein L, Kruger MP, Rubash HE: Acetabular anatomy and the transacetabular fixation of screws in total hip arthroplasty. J Bone Joint Surg Am
1990;72:501-508.

 

 

 

100.   What is the most frequent complication following primary total hip arthroplasty?

 

1-         Infection

2-         Dislocation

3-         Metal hypersensitivity

4-         Component loosening

5-         Thromboembolic disease

 

PREFERRED RESPONSE: 5

 

DISCUSSION: Thromboembolic disease can occur in up to 58% of unprotected patients and up to 20% of protected patients depending on the type of prophylaxis used, even though most thrombi are small and have little clinical consequence.  The primary goal of prophylaxis is to prevent symptomatic deep venous thrombosis and fatal pulmonary emboli.  Dislocation has been reported in up to 10% of primary cases, but generally acceptable rates of less than 5% are the norm.  Component loosening following primary total hip arthroplasty is rare prior to a 10-year follow-up, and 90% to 95% of patients should reach the 10-year follow-up without the need for revision for any reason.  Metal hypersensitivity is unusual, and nickel found in cobalt-chromium alloys is the most common offending agent.  Infection of primary total hip arthroplasty is less than 1%.

 

REFERENCES: Eftekhar N: Total Hip Arthroplasty. St Louis, MO, Mosby,1993, pp 1445-1676.

Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 56, 417-451.

 

 

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