2014 Hip and Knee

Question 1

Which of the following radiographic images is best for detecting anterior acetabular deficiency in the dysplastic hip?

1. Pelvic inlet
2. Judet
3. AP pelvis
4. False profile
5. Frog lateral

Answer 1

PREFERRED RESPONSE: 4

DISCUSSION: The false profile view of Lequesne and de Seze is obtained with the patient standing with the affected hip on the cassette, the ipsilateral foot parallel to the cassette, and the pelvis rotated 65° from the plane of the cassette. This view best assesses anterior coverage of the femoral head.

Garbuz DS, Masri BA, Haddad F, et al: Clinical and radiographic assessment the young adult with symptomatic dysplasia. Clin Orthop Relat Res 2004;418:18-22.

Delauney S, Dussault RG, Kaplan PA, et al: Radiographic measurements of dysplastic adult hips. Skel Radiol 1997;26:75-81.

Question 2

At the level of tibial bone resection in total knee arthroplasty, where does the common peroneal nerve lie?

1. Deep to the arcuate ligament
2. Closer to bone in larger legs
3. On the muscle belly of the popliteus
4. On the bony posterolateral corner of the tibia
5. Superficial to the lateral head of the gastrocnemius

Answer 2

PREFERRED RESPONSE: 5

DISCUSSION: At the level of tibial bone resection in total knee arthroplasty, the common peroneal nerve lies superficial to the lateral head of the gastrocnemius and is therefore protected by this structure. In an MRI study of 60 knees, the mean distance from the bony posterolateral corner of the tibia to the nerve was 1.49 cm, with no distance less than 0.9 cm. The distance from the bone to nerve was greater in larger legs.

Clarke HD, Schwartz JB, Math KR, et al: Anatomic risk of peroneal nerve injury with the “pie crust” technique for valgus release in total knee arthroplasty. J Arthroplasty 2004;19:40-44.

Anderson JE: Grant’s Atlas of Anatomy, ed 7. Baltimore, MD, Lippincott Williams & Wilkins, 1978, pp 4-52, 4-53.

Question 3

The anatomy of the sciatic nerve as it exits the pelvis is best described as exiting through the

1. greater sciatic notch and passing between the inferior gemellus and the obturator externus.
2. greater sciatic notch and passing between the piriformis and the superior gemellus.
3. obturator foramen and passing between the obturator internus and the obturator externus.
4. lesser sciatic notch and passing between the piriformis and the superior gemellus.
5. lesser sciatic notch and passing between the superior gemellus and the inferior gemellus.

Answer 3

PREFERRED RESPONSE: 2

DISCUSSION: The sciatic nerve is formed by the roots of the lumbosacral plexus. It exits the pelvis through the greater sciatic notch and appears in the buttock anterior to the piriformus. From that point, the sciatic nerve passes posteriorly over the superior gemellus, obturator internus, inferior gemellus, and quadratus femoris before it passes deep to the biceps femoris. The tendon of the obturator internus passes through the lesser sciatic notch.

Hoppenfeld S, deBoer P: Surgical Exposures in Orthopaedics: The Anatomic Approach. Philadelphia, PA, JB Lippincott, 1984, p 347.

Anderson JE: Grant’s Atlas of Anatomy, ed 7. Baltimore, MD, Lippincott Williams & Wilkins, 1978, pp 4-34, 4-36.

Hollingshead WH: Anatomy for Surgeons: The Back and Limbs, ed 2. Hagerstown, MD, Harper & Row, 1969, pp 607-609.

Question 4

What complication is more likely following excessive medial retraction of the anterior covering structures during the anterolateral (Watson-Jones) approach to the hip?

1. Numbness over the anterolateral thigh
2. Ischemia to the leg
3. Quadriceps weakness
4. Abductor insufficiency
5. Foot drop

Answer 4

PREFERRED RESPONSE: 3

DISCUSSION: The femoral nerve is the most lateral structure in the anterior neurovascular bundle. The femoral artery and vein lie medial to the nerve. Retractors placed in the anterior acetabular lip should be safe, although neurapraxia of the femoral nerve may occur if retraction is prolonged or forceful leading to quadriceps weakness. The femoral artery and nerve are well protected by the interposed psoas muscle. Damage to the lateral femoral cutaneous nerve, causing numbness over the anterolateral thigh, can occur while developing the interval between the tensor fascia latae and sartorious in the anterior (Smith-Petersen) approach but less likely in the Watson-Jones approach. Superior gluteal injury and accompanying abductor insufficiency may occur during excessive splitting of the glutei during the direct lateral (Hardinge) approach. Foot drop secondary to sciatic injury is more common with a posterior exposure or posterior retractor placement.

Hoppenfeld S, deBoer P: Surgical Exposures in Orthopaedics: The Anatomic Approach. Philadelphia, PA, JB Lippincott, 1984, p 325.

Anderson JE: Grant’s Atlas of Anatomy, ed 7. Baltimore, MD, Lippincott Williams & Wilkins, 1978, pp 4-17, 4-18.

Question 5

A 40-year-old man has had hip pain with increased activity over the past year. Examination reveals restriction of motion and tenderness with combined hip flexion, adduction, and internal rotation. An AP radiograph is shown in Figure 1. What is the most likely diagnosis?

1. Developmental dysplasia of the hip
2. Osteonecrosis
3. Perthes disease
4. Pseudogout
5. Femoral acetabular impingement

Answer 5

PREFERRED RESPONSE: 5

DISCUSSION: Femoral acetabular impingement (FAI) is a pathologic entity leading to pain, reduced range of motion in flexion and internal rotation, and development of secondary arthritis of the hip. There are two types of FAI: cam impingement and pincer impingement. Cam impingement is seen when a nonspherical femoral head produces a cam effect when the prominent portion to the femoral head rotates into the joint. This mechanism produces shear forces that damage articular cartilage. Radiographs reveal early joint degeneration and flattening of the head neck junction (pistol grip deformity) as seen in this image. The pincer type of impingement involves abnormal contact between the femoral head neck junction and the acetabulum, in the presence of a spherical femoral head.

Beall DP, Sweet CF, Martin HD, et al: Imaging findings of femoraoacetabular impingement syndrome. Skeletal Radiol 2005;34:691-701.

Mardones RM, Gonzalez C, Chen Q, et al: Surgical treatment of femoroacetabular impingement: Evaluation of the effect of the size of the resection. J Bone Joint Surg Am 2006;88:84-91.

Question 6

Bleeding is encountered while developing the internervous plane between the tensor fascia lata and the sartorius during the anterior approach to the hip. The most likely cause is injury to what artery?

1. Ascending branch of the lateral femoral circumflex
2. Superior gluteal
3. Femoral
4. Profunda femoris
5. Medial femoral circumflex

Answer 6

PREFERRED RESPONSE: 1

DISCUSSION: The ascending branch of the lateral femoral circumflex artery crosses the gap between the tensor fascia lata and the sartorious and must be identified and ligated or coagulated. The other vessels are out of the field of dissection.

McGann WA: Surgical approaches, in Barrack RL, Booth RE Jr, Lonner JH, et al, eds: Orthopaedic Knowledge Update: Hip and Knee Reconstruction, ed 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2006, p 312.

Hoppenfeld S, deBoer P: Surgical Exposures in Orthopaedics: The Anatomic Approach. Philadelphia, PA, JB Lippincott, 1984, p 304.

Question 7

When using the direct lateral (or Hardinge) approach for hip arthroplasty, three muscles are detached from the femur. In addition to the vastus lateralis, they include the

1. iliopsoas and sartorius.
2. piriformis and obturator internus.
3. gluteus maximus and tensor fascia lata.
4. gluteus minimus and rectus femoris.
5. gluteus medius and gluteus minimus.

Answer 7

PREFERRED RESPONSE: 5

DISCUSSION: This approach is criticized for the episodic limp associated with the muscle detachment and reattachment. Classically, two thirds of the gluteus medius are detached as a sleeve with the vastus lateralis. This exposes the gluteus minimus and the ligament of Bigelow. These must also be detached to allow dislocation of the hip and osteotomy of the femoral neck. The rectus femoris lies medially and anteriorly and does not need to be addressed. The piriformis and obturator internus are exposed during the posterior approach. Neither the gluteus maximus nor tensor fascia lata attach to the anterior femur. The sartorius and iliopsoas are not exposed during this dissection.

Hoppenfeld S, deBoer P, eds: Surgical Exposures in Orthopaedics: The Anatomic Approach. Philadelphia, PA, JB Lippincott, 1984, pp 333-335.

Hardinge K: The direct lateral approach to the hip. J Bone Joint Surg Br 1982;64:17-19.

Question 8

Figure 2 shows the radiograph of a patient who underwent a total knee revision with a posterior stabilized mobile-bearing prosthesis and who now has recurrent knee dislocations. What is the most likely cause?

1. Loose extension gap
2. Loose flexion gap
3. Malrotation of the tibial component
4. Malrotation of the femoral component
5. Poor prosthetic design

Answer 8

PREFERRED RESPONSE: 2

DISCUSSION: The patient has a posterior stabilized total knee revision, and the femoral component has dislocated over the tibial polyethylene cam/post. This usually indicates a loose flexion gap, or flexion instability. A loose flexion gap can occur due to undersizing of the femoral component, anteriorization of the femoral component, excessive distal augmentation of the distal femur, or collateral ligament insufficiency, especially if combined with posterior capsular insufficiency. Isolated laxity of the extension gap (with a well-balanced flexion gap) causes varus/valgus instability, but it rarely causes the femoral component to “jump” the tibial cam of a posterior stabilized tibial insert. Malrotation of the components may cause patellar instability or a rotational instability of the tibiofemoral joint but should not cause a frank posterior dislocation of the tibia, unless combined with other errors of balancing. Although a mobile-bearing total knee arthroplasty may be more sensitive to errors in balancing than a fixed-bearing total knee arthroplasty, this complication does not reflect a faulty prosthetic design.

Haas SB, Ammeen DJ, Engh GA, et al: Revision total knee replacement, in Pellicci PM, Tria AJ Jr, Garvin KL, eds: Orthopaedic Knowledge Update: Hip and Knee Reconstruction, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 339-365.

Lotke PA, Garino JP: Revision Total Knee Arthroplasty. New York, NY, Lippincott-Raven, 1999, pp 173-186, 227-249.

Clarke HD, Scuderi GR: Flexion instability in primary total knee replacement. J Knee Surg 2003;16:123-128.

Question 9

Figures 3A and 3B show the radiographs of a 72-year-old man with aseptic loosening of the tibial component of his total knee arthroplasty. Optimal management should include

1. tibial revision only, without stems or augmentations.
2. tibial revision only, with stems and augmentations.
3. revision of the tibial and femoral components, without stems or augmentations.
4. revision of the tibial and femoral components, with stems and augmentations.
5. primary arthrodesis.

Answer 9

PREFERRED RESPONSE: 4

DISCUSSION: The radiographs show massive subsidence of the lateral side of the tibia with severe tibial bone loss and a fractured proximal fibula. Reconstruction should consist of a large metal or bony lateral tibial augmentation, and a stem long enough to bypass the defect is required. The femoral and tibial components are articulating without any remaining polyethylene medially; therefore, the femoral component is damaged and needs revision. The insertions of the lateral ligaments are absent, thereby rendering the lateral side of the knee predictably unstable. Also, the large valgus deformity compromises the medial collateral ligament. The posterior cruciate ligament is also likely to be deficient with this much tibial bone destruction. The patient requires a posterior stabilized femoral component at the minimum, and possibly a constrained femoral component. Retention of the femoral component, even though it may be well fixed, jeopardizes the outcome.

Lotke PA, Garino JP: Revision Total Knee Arthroplasty. New York, NY, Lippincott-Raven, 1999, pp 137-250.

Insall JN, Windsor RE, Scott WN, et al, eds: Surgery of the Knee, ed 2. New York, NY, Churchill Livingstone, 1993, pp 935-957.

Haas SB, Ameen DJ, Engh GA, et al: Revision total knee replacement, in 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.

Question 10

Figure 4 shows the AP radiograph of a patient with diabetes mellitus who has knee pain. A semiconstrained knee prosthesis was used in this patient to prevent which of the following complications?

1. Infection
2. Instability
3. Stiffness
4. Bone loss
5. Malalignment

Answer 10

PREFERRED RESPONSE: 2

DISCUSSION: The radiographic appearance of the joint is highly suspicious for neuropathic joint (Charcot joint). Evidence of bone loss on both the tibial and the femoral sides may necessitate the use of metal and/or bone augments. Patients with a neuropathic joint often have excellent range of motion, and postoperative stiffness is not a problem. The main problem with these patients is instability that occurs secondary to ligamentous laxity. Use of a semiconstrained prosthesis prevents the latter complication.

Parvizi J, Marrs J, Morrey BF: Total knee arthroplasty for neuropathic (Charcot) joints. Clin Orthop 2003;416:145-150.

Kim YH, Kim JS, Oh SW: Total knee arthroplasty in neuropathic arthropathy. J Bone Joint Surg Br 2002;84:216-219.

Question 11

A 75-year-old woman who fell on her right knee now reports pain and is unable to bear weight. History reveals that she underwent total knee arthroplasty on the right knee 6 years ago. Radiographs are shown in Figure 5. Management should now consist of

1. closed reduction and casting for 6 weeks.
2. open reduction and internal fixation, using a locked intramedullary rod.
3. open reduction and internal fixation, using two cancellous screws.
4. open reduction and internal fixation, using a locked plate and screws.
5. open reduction and internal fixation and revision of the femoral component.

Answer 11

PREFERRED RESPONSE: 5

DISCUSSION: The radiographs show a loose femoral component with an associated medial condyle distal femoral fracture. The treatment of choice is open reduction and internal fixation with revision of the femoral component because of the femoral component loosening.

Moran MC, Brick GW, Sledge CB, et al: Supracondylar femoral fracture following total knee arthroplasty. Clin Orthop 1996;324:196-209.

McLaren AC, DuPont JA, Schroeber DC: Open reduction internal fixation of supracondylar fractures above total knee arthroplasties using the intramedullary supracondylar rod. Clin Orthop 1994;302:194-198.

Figgie MP, Goldberg VM, Figgie HE III, et al: The results of treatment of supracondylar fracture above total knee arthroplasty. J Arthroplasty 1990;5:267-276.

Question 12

A 64-year-old man undergoes a primary total knee arthroplasty. Three months after surgery he reports persistent pain, weakness, and difficulty ambulating. Postoperative radiographs are shown in Figures 6A through 6C. What is the best course of action at this time?

1. Hinged knee brace
2. Patellar component revision with a tantalum implant and lateralization of the patella
3. Revision knee arthroplasty with greater internal rotation of the tibial component
4. Revision total knee arthroplasty with a lateral release and external rotation of the femoral component
5. Revision total knee arthroplasty with a lateral release and internal rotation of the femoral component

Answer 12

PREFERRED RESPONSE: 4

DISCUSSION: The Merchant view reveals subluxation of the patellar component. The etiology of maltracking of the patella includes internal rotation of the femoral component, internal rotation of the tibial component, excessive patellar height, and lateralization of the patella component. The treatment of choice in this patient is revision total knee arthroplasty with external rotation of the femoral component. Preoperatively the patient also may require a lateral release, revision of the tibial component if it is internally rotated, and possibly a soft-tissue realignment. Component malalignment needs to be addressed first.

Kelly MA: Extensor mechanism complications in total knee arthroplasty. Instr Course Lect 2004;53:193-199.

Malkani AL, Karandikar N: Complications following total knee arthroplasty. Sem Arthroplasty 2003;14:203-214.

Norman AJ, Scott S, David GN, eds: Master Techniques in Knee Arthroplasty, ed 2. Philadelphia, PA, Lippincott Williams & Wilkins, 2003.

Question 13

Compared to metal-on-polyethylene total hip bearing surfaces, the debris particles generated by metal-on-metal articulations are

1. larger and less numerous.
2. larger and more numerous.
3. smaller and less numerous.
4. smaller and more numerous.
5. not detectable.

Answer 13

PREFERRED RESPONSE: 4

DISCUSSION: Retrieval studies have shown that the debris particles produced by metal-on-metal articulations in total hip arthroplasty are several orders of magnitude smaller and may be up to 100 times more numerous than those found with metal-on-polyethylene articulations.

Davies AP, Willert HG, Campbell PA, et al: An unusual lymphocytic perivascular infiltration in tissues around contemporary metal-on-metal joint replacements. J Bone Joint Surg Am 2005;87:18-27.

Firkins PJ, Tipper JL, Saadatzadeh MR, et al: Quantitative analysis of wear and wear debris from metal-on-metal hip prostheses tested in a physiological hip joint simulator. Biomed Mater Eng 2001;11:143-157.

Question 14

A 60-year-old patient had the procedure shown in Figure 7 performed 5 years ago. During transition to a total knee arthroplasty (TKA), what patellar problem is commonly encountered intraoperatively?

1. Fracture
2. Patella baja
3. Patella alta
4. Osteonecrosis
5. Maltracking

Answer 14

PREFERRED RESPONSE: 2

DISCUSSION: Patella baja is commonly encountered when converting a high tibial osteotomy (HTO) to a TKA. Patella baja most likely occurs because of scarring. Meding and associates’ study did not show an increased rate of lateral release when converting a knee that had undergone a previous HTO.

Yoshino N, Shinro T: Total knee arthroplasty after failed high tibial osteotomy, in Callaghan JJ, Rosenberg AG, Rubash HE, et al, eds: The Adult Knee. Philadelphia, PA, JB Lippincott, 2003, vol 2, pp 1265-1271.

Meding JB, Keating EM, Ritter MA, et al: Total knee arthroplasty after high tibial osteotomy: A comparison study in patients who had bilateral total knee replacement. J Bone Joint Surg Am 2000;82:1252-1259.

Question 15

Figures 8A and 8B show the radiographs of a 75-year-old man who underwent a revision total knee arthroplasty with a long-stemmed tibial component. In rehabilitation, he reports fullness and tenderness in the proximal medial leg (at the knee). The strategy that would best limit this postoperative problem is use of

1. a base plate with an offset tibial stem attachment.
2. a bone ingrowth surface on the augment.
3. a nonstemmed tibial base plate.
4. allograft bone instead of metal augments.
5. bone cement to smooth the outline of the proximal medial tibia.

Answer 15

PREFERRED RESPONSE: 1

DISCUSSION: The problem with this reconstruction is the medial protrusion of the base plate. The use of a base plate with an offset stem can prevent the protrusion and thus the impingement and pain. Allograft bone or smoothing the outline with cement would be just as prominent and likely to cause pain. An ingrowth surface may improve soft-tissue attachment but would still leave the implant protruding medially and likely to cause pain. A nonstemmed tibial base plate would lead to less medial protrusion but at the expense of a smaller area for load carriage on the proximal tibia.

REFERENCE: Gustke K: Cemented tibial stems are not requisite in revision. Orthopedics 2004;27:991-992.

Question 16

Figure 9 shows the AP radiograph of an ambulatory 76-year-old patient. What is the most appropriate surgical treatment option for this patient?

1. Revision arthroplasty using a cemented femoral component
2. Impaction allografting of the femoral component
3. Proximal femoral replacement arthroplasty
4. Resection arthroplasty
5. Hip arthrodesis

Answer 16

PREFERRED RESPONSE: 3

DISCUSSION: The patient has a periprosthetic fracture around a loose cemented femoral component. The proximal bone stock is poor; therefore, this fracture may be categorized as Vancouver 3-B. Hip arthrodesis and resection arthroplasty provide suboptimal results, particularly for ambulatory patients. Although impaction allografting may be an option to restore the bone stock in a younger patient, the latter procedure will be very difficult to perform when the proximal bone is poor in quality and fractured. Cementing another component into this wide femur is not an option. The best option for revision of the femoral component in this elderly patient is proximal femoral replacement arthroplasty.

Malkani AL, Settecerri JJ, Sim FH, et al: Long-term results of proximal femoral replacement for non-neoplastic disorders. J Bone Joint Surg Br 1995;77:351-356.

Parvizi J, Sim FH: Proximal femoral replacements with megaprostheses. Clin Orthop 2004;420:169-175.

Question 17

Increasing articular conformity of the tibial polyethylene insert of a fixed-bearing total knee arthroplasty (TKA) prosthesis will have which of the following biomechanical effects?

1. Decreased contact stress within the polyethylene
2. Decreased risk of patellofemoral instability
3. Decreased risk of mechanical loosening
4. Increased risk of subsurface polyethylene cracking
5. Increased tibial rollback during flexion

Answer 17

PREFERRED RESPONSE: 1

DISCUSSION: Increasing articular conformity increases the surface area for contact between the polyethylene and the femoral component. Advantages of this include lower peak contact stress within the polyethylene and less risk of polyethylene fatigue failure. Patellofemoral tracking is unchanged by increasing conformity unless gross component apposition is present. A potential disadvantage of increasing conformity includes some restriction in tibial rollback. Modest changes in conformity have not been shown to alter the rate of mechanical loosening. If conformity was increased to the extent of significant constraint, a potential increased risk of loosening would be expected, not a decrease. Design of modern TKAs includes a compromise in achieving enough constraint to lower polyethylene stress, without providing so much constraint as to limit kinematics and stress the fixation interfaces.

D’Lima DD, Chen PC, Colwell CW Jr: Polyethylene contact stresses, articular congruity, and knee alignment. Clin Orthop 2001;392:232-238.

Wright TM: Biomechanics of total knee design, in Pellicci PM, Tria AJ Jr, Garvin KL, eds: Orthopaedic Knowledge Update: Hip and Knee Reconstruction, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 265-274.

Question 18

A 63-year-old woman reports giving way of the knee and pain after undergoing primary total knee arthroplasty (TKA) 1 year ago. Examination reveals that the knee is stable in full extension but has gross anteroposterior instability at 90° of flexion. The patient can fully extend her knee with normal quadriceps strength. Studies for infection are negative. AP and lateral radiographs are shown in Figures 10A and 10B, respectively. What is the appropriate management?

1. Anti-inflammatory drugs
2. Knee brace
3. Physical therapy for quadriceps strengthening
4. Revision to a thicker polyethylene insert
5. Revision to a larger, posterior stabilized implant

Answer 18

PREFERRED RESPONSE: 5

DISCUSSION: The radiographs show posterior flexion instability that is the result of a flexion-extension gap imbalance and posterior cruciate ligament incompetence after a posterior cruciate ligament-retaining TKA. The femur is anteriorly displaced on the tibia, with lift-off of the femoral component from the tibial polyethylene. Revision to a larger femoral component will address the larger flexion gap relative to the extension gap, and a posterior stabilized implant will address the posterior cruciate ligament insufficiency. Pagnano and associates, reporting on a series of painful TKAs previously diagnosed as pain of unknown etiology, showed that the pain was secondary to flexion instability. Pain relief was achieved by revision to a posterior stabilized implant.

Pagnano MW, Hanssen AD, Lewallen DG, et al: 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, et al: Early failures in total knee arthroplasty. Clin Orthop 2001;392:315-318.

Question 19

Stiffness can occur following total knee arthroplasty. What is the most appropriate management for a patient who has deteriorating arc of motion after undergoing a revision knee arthroplasty 9 months ago?

1. Aggressive physical therapy
2. Manipulation under anesthesia
3. Investigation for periprosthetic infection
4. Revision knee arthroplasty
5. Resection arthroplasty

Answer 19

PREFERRED RESPONSE: 3

DISCUSSION: Stiffness following total knee arthroplasty can be a disabling condition. There are many reasons for loss of knee motion following total knee arthroplasty. Technical errors, such as overstuffing of the patella, malpositioning of the components, and ligamentous imbalance, all are known to result in stiffness following total knee arthroplasty. In some patients with a possible genetic predisposition, aggressive arthrofibrosis may develop and result in loss of knee motion. In any patient who has deteriorating knee motion, particularly after revision arthroplasty, deep infection should be ruled out. Although on occasion surgical intervention may be required to address knee stiffness, the outcome of revision surgery is poor if no reason for stiffness can be determined.

Kim J, Nelson CL, Lotke PA: Stiffness after total knee arthroplasty: Prevalence of the complication and outcomes of revision. J Bone Joint Surg Am 2004;86:1479-1484.

Gonzalez MH, Mekhail AO: The failed total knee arthroplasty: Evaluation and etiology. J Am Acad Orthop Surg 2004;12:436-446.

Question 20

A 59-year-old woman who underwent a total hip arthroplasty 5 years ago now has recurrent dislocation following bariatric surgery and a weight loss of 200 lb. An attempt at conversion to a larger head size and trochanteric advancement has failed. Her components are well aligned. What is the best course of action?

1. Resection arthroplasty
2. Hip abduction brace
3. Constrained acetabular liner
4. Thermal ablation of the posterior capsule
5. Conversion to a bipolar prosthesis

Answer 20

PREFERRED RESPONSE: 3

DISCUSSION: When a patient has well-aligned components and soft-tissue tensioning with a larger femoral head and trochanteric advancement has failed, options are limited. The use of a constrained acetabular liner is the best option in this situation. Goetz and associates and Shrader and associates have demonstrated good results with these implants. Shrader and associates used this device on 109 patients with recurrent instability with a successful outcome in all but 2 patients. Resection arthroplasty is a salvage situation and currently is not the best option. A hip abduction brace does not address the soft-tissue laxity. Conversion to a bipolar arthroplasty, although possibly minimizing the incidence of dislocation, will lead to groin pain and migration of the component with diminished functional results.

Goetz DD, Capello WN, Callaghan JJ, et al: Salvage of recurrently dislocating hip prosthesis with use of a constrained acetabular component: A retrospective analysis of fifty-six cases. J Bone Joint Surg Am 1998;80:502-509.

Shrader MW, Parvizi J, Lewallen DG: The use of constrained acetabular component to treat instability after total hip arthroplasty. J Bone Joint Surg Am 2003;85:2179-2183.

Hamilton WG, McAuley JP: Evaluation of the unstable total hip arthroplasty. Inst Course Lect 2004;53:87-92.

Question 21

Figure 11 shows the radiograph of an otherwise healthy 62-year-old woman who fell. Management should consist of

1. revision total hip arthroplasty with a cemented femoral component and adjuvant fracture fixation.
2. revision total hip arthroplasty with a cementless femoral component and adjuvant fracture fixation.
3. open reduction and internal fixation of the fracture and retention of the original components.
4. removal of the components, open reduction and internal fixation of the fracture, and delayed replantation of the components when the fracture is healed.
5. resection arthroplasty and internal fixation of the fracture.

Answer 21

PREFERRED RESPONSE: 2

DISCUSSION: The radiograph reveals that the femoral component is grossly loose as evidenced by disruption of the cement column; therefore, retention of the original components will not yield a successful outcome. A cementless revision is the procedure of choice. A strut graft and/or plate may be added at the surgeon’s discretion. A resection arthroplasty would only be considered in a nonambulatory patient. Cemented fixation of the revision component would be problematic given the numerous fracture fragments and the inability to contain the cement.

Springer BD, Berry DJ, Lewallen DG: Treatment of periprosthetic fractures following total hip arthroplasty with femoral component revision. J Bone Joint Surg Am 2003;85:2156-2162.

Duwelius PJ, Schmidt AH, Kyle RF, et al: A prospective, modernized treatment protocol for periprosthetic femur fractures. Orthop Clin North Am 2004;35:485-492.

Question 22

A 75-year-old woman undergoes hybrid total hip arthroplasty for osteoarthritis. A postoperative radiograph obtained in the recovery room is shown in Figure 12. Treatment should now consist of

1. open reduction and internal fixation with strut graft and cerclage wire.
2. open reduction and internal fixation with a plate, screws, and bone graft.
3. exchange of the femoral components with insertion of a long stem cementless implant.
4. cast immobilization.
5. minimal weight bearing and observation.

Answer 22

PREFERRED RESPONSE: 5

DISCUSSION: Intraoperative femoral fractures can often be avoided by careful preoperative planning to optimize implant design and size. Most fractures occur during implantation of a cementless implant; many can be avoided by careful femoral preparation and component implantation, with particular caution in osteopenic bone. Intraoperative femoral fractures are managed according to fracture severity. Minor cracks that do not affect stability or femoral integrity can often be managed intraoperatively with cerclage fixation, limited weight bearing, and observation. Femoral fractures that compromise implant stability or femoral integrity require fracture fixation with cerclage wires, strut grafts, or plates and may require conversion to a long-stem implant. This patient’s fracture is nondisplaced and the implant is well seated; therefore, limited weight bearing is considered appropriate management.

Lee SR, Bostrom MP: Periprosthetic fractures of the femur after total hip arthroplasty. Instr Course Lect 2004;53:111-118.

Kelley SS: Periprosthetic femoral fractures. J Am Acad Orthop Surg 1994;2:164-172. Berry DJ: Management of periprosthetic fractures: The hip. J Arthroplasty 2002;17:11-13.

Question 23

A 58-year-old man reports a 2-month onset of groin pain with no history of trauma. Examination reveals that range of motion of the hip is mildly restricted, and he has pain with both weight bearing and at rest. An MRI scan is shown in Figure 13. Treatment 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.

Answer 23

PREFERRED RESPONSE: 1

DISCUSSION: The MRI findings show highly increased signal through the entire femoral head and neck on short tau inversion recovery imaging, diagnostic of transient osteoporosis of the femoral head. This disease entity can be seen in middle-aged men, and should be treated nonsurgically. The natural history is that of self-resolution.

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.

Question 24

Figure 14 shows the radiograph of a 32-year-old patient with right hip pain that has failed to respond to nonsurgical management. What is the most appropriate surgical treatment at this time?

1. Femoral derotational osteotomy
2. Total hip arthroplasty
3. Arthrodesis
4. Surgical dislocation of the hip
5. Periacetabular osteotomy

Answer 24

PREFERRED RESPONSE: 5

DISCUSSION: The radiograph reveals developmental dysplasia of both hips. The patient has classic anterolateral undercoverage of the femoral head on the right side as demonstrated by a high acetabular index (measured at 27°). Anterior undercoverage can be determined by drawing the marking for the anterior wall that fails to overlap the femoral head in this patient. Currently in North America, the most accepted surgical management for symptomatic dysplasia of the hip with good joint space is a Bernese (Ganz) periacetabular osteotomy. Surgical dislocation of the hip and femoroacetabular osteoplasty may be considered for patients with symptomatic femoroacetabular impingement of the hip.

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

Trousdale RT, Ekkernkamp A, Ganz R, et al: Periacetabular and intertrochanteric osteotomy for the treatment of osteoarthrosis in dysplastic hips. J Bone Joint Surg Am 1995;77:73-85.

Question 25

A patient reports pain in the hip with functional positioning. With the patient supine, pain in which of the following positions would be typical for femoral acetabular impingement?

1. Hip is internally rotated, passively flexed to 90°, and adducted
2. Hip is internally rotated, passively flexed to 90°, and abducted
3. Hip is externally rotated, maximally flexed to 90°, and adducted
4. Hip is externally rotated, passively flexed to 90°, and abducted
5. Hip is externally rotated, maximally flexed, and abducted

Answer 25

PREFERRED RESPONSE: 1

DISCUSSION: Patients with dysplasia often have a hypertrophic labrum. Abnormal contact between the femoral neck and the acetabular rim leads to labral injury, especially in the anterior-superior acetabular zone. Typically, young patients with the condition report pain with activity or long periods of sitting or driving. The hips often have limited motion, in particular in internal rotation and flexion. Forceful adduction with the maneuver causes pain.

Parvizi J, Purtill JJ: Hip, pelvic reconstruction, and arthroplasty, in Vaccaro AR, ed: Orthopaedic Knowledge Update, ed 8. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2005, pp 411-424.

Beck M, Leunig M, Parvizi J, et al: Anterior femoroacetabular impingement: Part II. Midterm results of surgical treatment. Clin Orthop 2004;418:67-73.

McCarthy JC, Noble PC, Schuck MR, et al: The role of labral lesions to development of early degenerative hip disease. Clin Orthop 2001;393:25-37.

Question 26

A 38-year-old man who is an avid tennis player has had persistent pain over the medial aspect of his knee for the past 6 years. He notes that the pain occurs on a daily basis with any significant activity. NSAIDs have failed to provide relief. Radiographs are shown in Figures 15A and 15B. What is the best course of action?

1. Total knee arthroplasty
2. Unicompartmental arthroplasty
3. Insertion of a unispacer
4. Tibial osteotomy
5. Knee arthroscopy

Answer 26

PREFERRED RESPONSE: 4

DISCUSSION: In a relatively young patient who is an avid tennis player, the treatment of choice is a joint-preserving procedure. The radiographs reveal varus alignment with loading of the medial compartment. After all nonsurgical management options have been used, the best treatment option is a medial opening wedge osteotomy. A lateral closing wedge osteotomy of the proximal tibia is also a reasonable option, but it is not one of the choices. A unicompartmental arthroplasty or a total knee arthroplasty would place significant restrictions in this patient. A unispacer may be a temporizing procedure but is controversial and without substantial data in the literature. The knee arthroscopy will not address the medial compartment osteoarthritis.

Nagel A, Insall JN, Scuderi GR: Proximal tibial osteotomy: A subjective outcome study. J Bone Joint Surg Am 1996;78:1353-1358.

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

Manifold SG, Kelly MA, Richardson L, et al: Osteotomies about the knee, in Fitzgerald RH, Kaufer H, Malkani AL, eds: Orthopaedics. St Louis, MO, Mosby, 2002, pp 947-961.

Question 27

Which of the following statements best describes the outcome of the routine use of continuous passive motion (CPM) machines after total knee arthroplasty (TKA)?

1. CPM is likely to improve early range of motion and final range of motion.
2. CPM may improve early range of motion but is unlikely to improve final range of motion.
3. CPM is likely to decrease postoperative pain.
4. CPM is likely to improve extension but not flexion.
5. CPM is likely to restore quicker ambulatory ability.

Answer 27

PREFERRED RESPONSE: 2

DISCUSSION: Although CPM machines are used widely in the United States for patients undergoing TKA, the benefit, if any, seems to be marginal. Numerous randomized trials have shown that final outcomes after TKA are unaffected by the use of CPM machines postoperatively. Some studies have suggested that use of CPM may improve flexion in the first few weeks, but any short-term benefit from the machine was lost by intermediate-term follow-up. Aside from potential improvement in flexion within the first few postoperative weeks, there does not appear to be any benefit from the machines. There is no improvement in pain, ambulation, or extension. The cost-effectiveness of these machines has been questioned by many authors.

Stern SH: The Knee: Rehabilitation, in Pellicci PM, Tria AJ, Garvin KL, eds: Orthopaedic Knowledge Update: Hip and Knee Reconstruction, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 287-293.

McInnes J, Larson MG, Daltroy LH, et al: A controlled evaluation of continuous passive motion in patients undergoing total knee arthroplasty. JAMA 1992;268:1423-1428.

Kumar PJ, McPherson EJ, Dorr LD, et al: Rehabilitation after total knee arthroplasty: A comparison of 2 rehabilitation techniques. Clin Orthop 1996;331:93-101.

Question 28

When performing knee arthroplasty, which of the following procedures provides the most consistent fixation for the tibial component?

1. Cementless fixation of the tibial component
2. Augmenting cementless fixation of the tibial component with pegs or screws
3. Cementing the metaphyseal portion and press fitting the keel of the tibial component
4. Cementing the metaphyseal and keel portions of the tibial component
5. Cemented fixation of the tibial component with screws

Answer 28

PREFERRED RESPONSE: 4

DISCUSSION: All of the options, except cementing the metaphyseal portion and press fitting the keel of the tibial component, have been shown to create strong and long-lasting constructs; however, cementing of both the platform and the keel offers the most predictable solution. Cementing the platform and not the keel has been shown to have a higher loosening rate than the more traditional methods of fully cementing or using screws to augment fixation.

REFERENCE: Froimson MI: Knee reconstruction and replacement, in Vaccaro AR, ed: Orthopaedic Knowledge Update, ed 8. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2005, pp 457-468.

Question 29

Figure 16 shows the radiograph of an 84-year-old woman who has pain and is unable to extend her knee. History reveals that she underwent total knee arthroplasty 8 years ago. Aspiration and studies for infection are negative. During revision surgery, management of the tibial bone loss should consist of

1. reconstruction with a metal augmented revision tibial implant.
2. reconstruction with a hinged prosthesis.
3. reconstruction with a structural allograft.
4. reconstruction with iliac crest bone graft.
5. filling the defect with cement.

Answer 29

PREFERRED RESPONSE: 1

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 large structural bone defects. A hinged prosthesis is not required in this setting. In this patient, a large amount of posterior cortex has been lost, making the area too large to fill with cement or iliac crest bone graft. Because of the patient’s age, the treatment of choice is a revision tibial implant and metal augments. Structural allograft would be suitable in a younger patient.

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, et al: 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.

Question 30

A 62-year-old woman with a bone mineral density (BMD) T-score of -2.0 sustained a subcapital fracture of her hip. She is an avid tennis player, and history reveals no previous fractures. What is the most appropriate follow-up care?

1. Antiresorptive bisphosphonate medication
2. A repeat dual-energy x-ray absorptiometry scan (DEXA) and treatment if the T-score is less than –2.5
3. A repeat DEXA scan and treatment if the T-score is greater than –1.5
4. No treatment because the BMD is not in osteoporotic range
5. Parathyroid hormone followed by surgery

Answer 30

PREFERRED RESPONSE: 1

DISCUSSION: A DEXA scan is most appropriately used to establish a baseline score. Even if the BMD is not within the osteoporotic range (T-score less than -2.5), a prior fragility fracture is a strong risk factor for a second fracture as a result of factors other than bone density, such as worsening vision or balance, confusion, or other predispositions to falls. The guidelines of the National Osteoporosis Foundation indicate that, following a fragility hip fracture, active antiosteoporotic medication should be initiated, whether or not a DEXA scan is performed. A recent study showed that antiresorptive therapy following a hip fracture reduces not only the risk of a second fracture but also overall mortality.

REFERENCE: Gardner MJ, Brophy RH, Demetrakopoulos D, et al: Interventions to improve osteoporosis treatment following hip fracture: A prospective, randomized trial. J Bone Joint Surg Am 2005;87:3-7.

Question 31

A 58-year-old patient who underwent bilateral hip arthroplasty 12 years ago now reports pain in his hips and difficulty with ambulation to the point where he now uses crutches. A radiograph of the hip and pelvis is shown in Figure 17. What is the best treatment option for this patient?

1. Revision hip arthroplasty with a bipolar implant
2. Revision hip arthroplasty with impaction grafting on the femoral and acetabular side
3. Revision hip arthroplasty with a cemented jumbo acetabular component
4. Revision hip arthroplasty with a cementless acetabular component
5. Acetabular component revision with a triflange protrusio ring

Answer 31

PREFERRED RESPONSE: 4

DISCUSSION: The radiographs reveal acetabular component failure with bone loss. There are several treatment options available. The best option for survivorship is a cementless porous-coated acetabular component. This patient may or may not require structural bone graft, which may need to be determined at the time of surgery. Bipolar implants and cemented acetabular components for revision surgery have not demonstrated long-term success. The use of a protrusio ring is reserved primarily for massive bone loss such as Paprosky type III bone loss with significant superior migration of the acetabular component. The best clinical results for acetabular component revision have been achieved with cementless porous-coated implants.

Haddad FS, Masri BA, Garbuz DS, et al: Acetabulum, in Fitzgerald RH, Kaufer H, Malkani AL, eds: Orthopaedics. St Louis, MO, Mosby, 2002, pp 923-936.

D’Antonio JA: Periprosthetic bone loss of the acetabulum: Classification and management. Orthop Clin North Am 1992;23:279-290.

Rubash HE, Sinha RK, Paprosky W, et al: A new classification system for the management of acetabular osteolysis after total hip arthroplasty. Instr Course Lect 1999;48:37-42.

Question 32

Embolic material (shown in Figure 18) generated during total knee arthroplasty (TKA) is composed of which of the following substances?

1. Fat only
2. Fat and air
3. Fat and marrow
4. Fat and cement
5. Fat and bone

Answer 32

PREFERRED RESPONSE: 3

DISCUSSION: Emboli are created during TKA. Usually there is an increased incidence with the use of intramedullary rods that disrupt the marrow contents. These are not fat emboli per se. They are material composed of fat cells and marrow that act like pulmonary emboli to obstruct small arterioles in the lung. They are different from free fat emboli that are seen in fractures and that lead to chemical injury to the lung rather than obstructive injury.

REFERENCES: Markel DC, Femino JE, Farkas P, et al: Analysis of lower extremity embolic material after total knee arthroplasty in a canine model. J Arthroplasty 1999;14:227-232.

Pell AC, Christie J, Keating JF, et al: The detection of fat embolism by transoesophageal echocardiography during reamed intramedullary nailing: A study of 24 patients with femoral and tibial fractures. J Bone Joint Surg Br 1993;75:921-925.

McGrath BJ, Hsia J, Boyd A, et al: Venous embolization after deflation of lower extremity tourniquets. Anesth Analg 1994;78:349-353.

Question 33

A 30-year-old patient has had severe left hip pain and difficulty ambulating, necessitating the use of a cane, for the past 6 months. A photomicrograph of the femoral head sectioned at the time of surgery is shown in Figure 19. What is the most likely diagnosis?

1. Renal osteodystrophy
2. Pyogenic osteomyelitis
3. Osteoarthritis
4. Osteonecrosis
5. Tuberculosis osteomyelitis

Answer 33

PREFERRED RESPONSE: 4

DISCUSSION: The photomicrograph demonstrates a wedge-shaped infarct with femoral head collapse; therefore, the diagnosis is osteonecrosis of the femoral head. Perthes disease and osteoarthritis do not involve a wedge-shaped defect. Tuberculosis of the hip joint results in greater destruction of the articular cartilage.

Basset LW, Mirra JM, Cracchiolo A III: Ischemic necrosis of the femoral head: Correlation between magnetic resonance imaging and histologic sections. Clin Orthop 1987;223:181-187.

Sugano N: Osteonecrosis, in Fitzgerald RH, Kaufer H, Malkani AL, eds: Orthopedics. St Louis, MO, Mosby, 2002, pp 878-887.

Question 34

When comparing mobile-bearing total knee arthroplasty (TKA) to fixed-bearing total condylar arthroplasty, the mobile-bearing procedure provides

1. no improvement in survivorship.
2. approximately 15° greater flexion.
3. appreciable reduction in wear rates.
4. a faster recovery profile.
5. better quadriceps strength.

Answer 34

PREFERRED RESPONSE: 1

DISCUSSION: Survivorship is similar in the two groups. In a recent study, mobile-bearing TKAs showed a slightly higher maximum flexion than the total condylar fixed-bearing-type designs (112° versus 108° with no difference in recovery rate). Using a fixed-bearing or a mobile-bearing design did not seem to influence the recovery rate in early results after knee arthroplasty. Mobile-bearing arthroplasties are suggested, in theory, to offer a reduction in polyethylene wear; however, clinical studies have not yet proven this. Recovery rates have yet to be statistically seen as improved with either method. Differences in strength have not been shown.

Aglietti P, Baldini A, Buzzi R, et al: Comparison of mobile-bearing and fixed-bearing total knee arthroplasty: A prospective randomized study. J Arthroplasty 2005;20:145-153.

Sorrells RB: The rotating platform mobile bearing TKA. Orthopedics 1996;19:793-796.

Dennis DA, Komistek RD: Kinematics of mobile-bearing total knee arthroplasty. Instr Course Lect 2005;54:207-220.

Question 35

Based on the type of articulation shown in Figure 20, wear is not affected by which of the following factors?

1. Radial mismatch of the femoral head to the acetabular component
2. Sphericity of the bearings
3. Surface finish of the articulation
4. Carbon content of the metal-on-metal bearing
5. Head-to-neck ratio

Answer 35

PREFERRED RESPONSE: 5

DISCUSSION: Wear in total hip arthroplasty is a very complex phenomenon. The radial mismatch of the femoral head to the acetabular component has been shown in multiple studies to be a significant factor in wear. The mismatch can neither be too small nor too large. When the mismatch is too small, seizing of the implants can occur. When the mismatch is too large, contact stresses increase and produce exceptionally high wear. The ideal radial mismatch should be approximately 50 microns. Surface roughness and ball sphericity are two items that are extremely important with respect to wear. High carbon content has been shown to decrease wear. This device has a very large head-to-neck ratio, so impingement-related wear is unlikely.

Amstutz HC, Grigoris P: Metal on metal bearings in hip arthroplasty. Clin Orthop 1996;329:S11-S34.

Amstutz HC, Campbell P, McKellop H, et al: Metal on metal total hip replacement workshop consensus document. Clin Orthop 1996;329:S297-S303.

McKellop H, Park SH, Chiesa R, et al: In vivo wear of three types of metal on metal hip prostheses during two decades of use. Clin Orthop 1996;329:S128-S140.

Question 36

A 78-year-old patient undergoing revision total knee arthroplasty has bone loss throughout the knee at the time of revision. A distal femoral augment is used to restore the joint line. One month after surgery, the patient reports pain and is unable to ambulate. A lateral radiograph is shown in Figure 21. What is the most likely etiology of this problem?

1. Inadequate restoration of the joint line
2. Patellar tendon rupture
3. Excessive internal rotation of the tibial component
4. Flexion gap instability
5. Hyperextension of the femoral component

Answer 36

PREFERRED RESPONSE: 4

DISCUSSION: Instability is a leading cause of failure following total knee arthroplasty. Instability can present as global instability, extension gap (varus/valgus) instability, or flexion gap (anterior/posterior) instability. Treatment options are numerous based on the exact pathology. The radiograph reveals anterior/posterior instability with dislocation consistent with flexion gap instability. A loose flexion gap can allow the femoral component to ride above the tibial cam post mechanism, resulting in dislocation. Distal femoral augments treat extension gap instability, whereas tibial augments can treat both flexion and extension gap instability. Posterior condyle augments at the distal femur can also be used to treat flexion gap instability. Flexion gap instability is further aggravated by extension mechanism incompetence. Note the excessively thin patella on the lateral radiograph.

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

McAuley J, Engh GA, Ammeen DJ: Treatment of the unstable total knee arthroplasty. Inst Course Lect 2004;53:237-241.

Naudie DD, Rorabeck CH: Managing instability in total knee arthroplasty with constrained and linked implants. Instr Course Lect 2004;53:207-215.

Question 37

Figure 22 reveals a periprosthetic fracture around a cemented femoral stem in an 81-year-old patient with Paget disease and mild coagulopathy. What is the most appropriate reconstructive management on the femoral side?

1. Open reduction and internal fixation
2. Impaction allografting
3. Proximally coated femoral stem
4. Allograft prosthetic composite (APC)
5. Proximal femoral replacement (PFR)

Answer 37

PREFERRED RESPONSE: 5

DISCUSSION: This is an example of a Vancouver B3 periprosthetic fracture that consists of a fracture around a loose femoral stem with poor proximal bone support. Therefore, open reduction and internal fixation is not an option. PFR is an excellent choice for elderly inactive patients with poor femoral bone stock. The surgery can be performed in an expeditious manner, which is very important in a patient with mild coagulopathy. Impaction allografting and APC are both options for younger patients who have bone stock that needs to be restored. The results of revision arthroplasty using proximally coated stems, especially under these circumstances, are poor.

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

Parvizi J, Sim FH: Proximal femoral replacements with megaprostheses. Clin Orthop 2004;420:169-175.

Klein GR, Parvizi J, Rapuri V, et al: Proximal femoral replacement for treatment of periprosthetic fractures. J Bone Joint Surg Am 2005;87:1777-1781.

Question 38

A patient with a documented allergy to nickel requires a total knee arthroplasty. Which of the following prostheses is most likely to provide long-term success in this individual?

1. All-polyethylene tibial component and pure titanium femoral component
2. All-polyethylene tibial component and cobalt-chromium alloy femoral component
3. Cobalt-chromium alloy tibial component and cobalt-chromium alloy femoral component
4. Modular titanium tibial component and pure titanium femoral component
5. Modular titanium tibial component and oxidized zirconium femoral component

Answer 38

PREFERRED RESPONSE: 5

DISCUSSION: Nickel allergy is not an infrequent preoperative finding. The ramifications of such allergies in arthroplasty patients are poorly understood at this time. Stainless steel and cobalt-chromium alloys contain relatively high concentrations of nickel. Titanium, oxidized zirconium, and polyethylene do not contain significant amounts of nickel. Titanium is not a good surface for the articulating portion of the femoral component because of its propensity for metallosis. Oxidized zirconium is the only suitable femoral component for patients allergic to nickel. A modular titanium tibial component or an all-polyethylene tibial component would be satisfactory for these patients.

Laskin RS: An oxidized Zr ceramic surfaced femoral component for total knee arthroplasty. Clin Orthop 2003;416:191-196.

Nasser S, Campbell PA, Kilgus D, et al: Cementless total joint arthroplasty prostheses with titanium-alloy articular surfaces: A human retrieval analysis. Clin Orthop 1990;261:171-185.

Question 39

A 42-year-old man reports the recent onset of right hip pain. A radiograph and MRI scan are shown in Figures 23A and 23B. White blood cell count, erythrocyte sedimentation rate, and hip aspiration results are within normal limits. Management should now consist of

1. core decompression.
2. biopsy of the femoral head.
3. protected weight bearing and observation.
4. total hip arthroplasty.
5. percutaneous cannulated pin fixation of the femoral neck.

Answer 39

PREFERRED RESPONSE: 3

DISCUSSION: Transient osteoporosis of the hip is an uncommon problem, usually affecting women in the last trimester of pregnancy and middle-aged men. Symptoms include pain in the involved hip with temporary osteopenia; however, there is no joint space involvement. In this patient, the imaging findings are consistent with transient osteoporosis. Short repetition time/echo time images reveal diffusely decreased signal intensity in the femoral head and intracapsular region of the femoral neck. Increased signal intensity is seen with increased T2-weighting. Within a few months, the pain, as well as the imaging findings, will completely resolve without intervention. Distinguishing the diffuse features of transient osteoporosis of the hip from the segmental findings of osteonecrosis is essential. Unlike transient osteoporosis of the hip, osteonecrosis will have a double-density signal on MRI and may progress radiographically. Surgical intervention and oral corticosteriods are not indicated for treatment. Protected weight bearing until the pain resolves may decrease symptoms while the transient osteoporosis resolves.

Potter H, Moran M, Scheider R, et al: Magnetic resonance imaging in diagnosis of transient osteoporosis of the hip. Clin Orthop 1992;280:223-229.

Bijl M, van Leeuwen MA, van Rijswijk MH: Transient osteoporosis of the hip: Presentation of typical cases for review of the literature. Clin Exp Rheumatol 1999;17:601-604.

Montella BJ; Nunley JA, Urbaniak JR: Osteonecrosis of the femoral head associated with pregnancy: A preliminary report. J Bone Joint Surg Am 1999;81:790-798.

Question 40

During cemented total hip arthroplasty, peak pulmonary embolization of marrow contents occurs when the

1. hip is dislocated.
2. femoral neck is osteotomized.
3. acetabulum is prepared.
4. acetabular component is inserted.
5. femoral stem is inserted.

Answer 40

PREFERRED RESPONSE: 5

DISCUSSION: Peak embolization is observed during femoral stem insertion. Embolization is also observed during acetabular preparation and hip reduction.

Lewallen DG, Parvizi J, Ereth MH: Perioperative mortality associated with hip and knee arthroplasty, in Morrey BF, ed: Joint Replacement Arthroplasty, ed 3. Philadelphia, PA, Churchill-Livingstone, 2003, pp 119-127.

Ereth MH, Weber JG, Abel MD, et al: Cemented versus noncemented total hip arthroplasty: Embolism, hemodynamics, and intrapulmonary shunting. Mayo Clin Proc 1992;67:1066-1074.

Question 41

What are the optimal conditions for leaving the acetabular shell in place, replacing the acetabular liner, and grafting the osteolytic defect shown in Figure 24?

1. Nonmodular implant
2. Instability
3. Well-designed, well-fixed modular implant
4. Complete radiolucency of the acetabular component
5. Migration of the acetabular component

Answer 41

PREFERRED RESPONSE: 3

DISCUSSION: Dense pods of ingrowth into the porous coating of cementless ingrowth sockets are seen. Channels through the noningrown portion allow access to the trabecular bone of the ilium. Polyethylene wear debris can enter these areas through screw holes. Expansile, lytic lesions can result, which can become large without compromising implant fixation. Loosening is late and results from catastrophic loss of bone. A well-fixed acetabular component with a modular design, a well-designed locking mechanism, and a good survivorship history is a candidate for exchange of the liner and grafting of the osteolytic lesion.

Ries MD: Complications in primary total hip arthroplasty: Avoidance and management. Wear. Instr Course Lect 2003;52:257-265.

Dumbleton JH, Manley MT, Edidin AA: A literature review of the association between wear rate and osteolysis in total hip arthroplasty. J Arthroplasty 2002;17:649-661.

Maloney WJ: Osteolysis, in Pellicci PM, Tria AJ Jr, Garvin KL, eds: Orthopaedic Knowledge Update: Hip and Knee Reconstruction, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 175-180.

Question 42

A 53-year-old patient is seen in the emergency department after sustaining a fall onto her left hip. A current radiograph is shown in Figure 25. What is the best treatment option?

1. Bed rest and weight bearing for 6 to 8 weeks
2. Component retention and open reduction and internal fixation
3. Proximal femoral replacement prosthesis
4. Revision arthroplasty with a long cemented stem
5. Revision arthroplasty with a long porous-coated cylindrical stem

Answer 42

PREFERRED RESPONSE: 5

DISCUSSION: The patient has sustained a Vancouver B2 periprosthetic femoral fracture (a femoral fracture that occurs around or just distal to a loose stem, with adequate proximal bone stock). The stem is no longer fixed to proximal bone; therefore, retention of the femoral component is not recommended. Nonsurgical management is contraindicated because of the high risk of nonunion and malunion with significant component settling in the distal fragment and leg shortening. Revision femoral arthroplasty must attain distal fixation in adequate host bone, which is usually successful with a porous-coated cylindrical stem.

Parvizi J, Rapuri VR, Purtill JJ, et al: Treatment protocol for proximal femoral periprosthetic fractures. J Bone Joint Surg Am 2004;86:8-16.

Springer BD, Berry DJ, Lewallen DG: Treatment of periprosthetic femoral fractures following total hip arthroplasty with femoral component revision. J Bone Joint Surg Am 2003;85:2156-2162.

Question 43

Figure 26 shows the radiograph of a 65-year-old man who underwent a revision arthroplasty to remove a loose, cemented femoral stem. When planning the postoperative restrictions, the surgeon should be aware that

1. the approach used reduces the torque-to-failure (fracture) of the construct to less than 50% of the intact femur.
2. the technique of repair can return the reconstructed prosthesis/bone composite to nearly the strength of the intact femur.
3. there is no relationship between the density of the native bone and the strength of the prosthesis/bone composite.
4. the addition of bone graft substitute or autograft has been shown to lessen the time to complete healing.
5. there is a one in five chance of fracture with this technique; therefore, the surgeon must carefully weigh the potential benefits versus this risk.

Answer 43

PREFERRED RESPONSE: 1

DISCUSSION: The transfemoral approach, also known as the extended trochanteric osteotomy, is an important technique to master for revision hip surgery. When performed correctly, it allows excellent exposure of the femoral canal and aids in exposure of the acetabulum. As demonstrated in the study cited, however, it markedly reduces the torque that the composite can withstand without failure. This type of basic science study is important to guide postoperative rehabilitation.

REFERENCE: Noble AR, Branham D, Willis M, et al: Mechanical effects of the extended trochanteric osteotomy. J Bone Joint Surg Am 2005;87:521-529.

Question 44

A 37-year-old man who works in a factory has isolated, lateral unicompartmental pain about his knee with activities. Nonsurgical management has failed to provide relief. The radiograph shown in Figure 27 reveals a tibiofemoral angle of approximately 15° that is clinically correctable to neutral. What is the best surgical option in this patient?

1. Unicompartmental arthroplasty
2. Total knee arthroplasty
3. Lateral closing wedge proximal tibial osteotomy
4. Medial opening wedge proximal tibial osteotomy
5. Medial closing wedge supracondylar femoral osteotomy

Answer 44

PREFERRED RESPONSE: 5

DISCUSSION: Patients with a valgus alignment about the knee can have lateral compartment arthritis. Similar to a high tibial osteotomy, a supracondylar femoral osteotomy is indicated in younger patients who have a more active lifestyle and isolated unicompartmental disease. In this young patient who works in a factory and has a valgus knee, a medial closing wedge supracondylar femoral osteotomy is the treatment of choice. The role of arthroplasty is limited in younger patients.

Mathews J, Cobb AG, Richardson S, et al: Distal femoral osteotomy for lateral compartment osteoarthritis of the knee. Orthopedics 1998;21:437-440.

Cameron HU, Botsford DJ, Park YS: Prognostic factors in the outcome of supracondylar femoral osteotomy for lateral compartment osteoarthritis of the knee. Can J Surg 1997;40:114-118.

Question 45

Figure 28 shows the AP radiograph of an active 80-year-old patient with an acetabular fracture. The fracture was initially managed nonsurgically; however, the patient is now scheduled to undergo total hip arthroplasty. What is the treatment of choice for the contained acetabular bone defect?

1. Bipolar femoral component
2. Acetabular cage
3. Large structural allograft
4. Use of the femoral head
5. Double-bubble acetabular cup

Answer 45

PREFERRED RESPONSE: 4

DISCUSSION: Acetabular fractures can result in a relative or actual acetabular bone defect. The medial blowout fracture of the acetabulum has united well in this patient. It is likely that a medial shell of bone will be present during hip arthroplasty. The femoral head may be used as morcellized or structural bone to augment the medial defect and is preferred to structural allograft. Bipolar hip arthroplasty is notorious for medial migration in patients without a medial bone defect; therefore, it will not be a good choice in this patient. Filling the defect with methylmethacrylate cement, though an option, is not the best option in this active patient with an extensive medial defect. A double-bubble acetabular cup is used for patients with deficiency of the bone in the dome region.

Mears DC: Surgical treatment of acetabular fractures in elderly patients with osteoporotic bone. J Am Acad Orthop Surg 1999;7:128-141.

Bellabarba C, Berger RA, Bentley CD, et al: Cementless acetabular reconstruction after acetabular fracture. J Bone Joint Surg Am 2001;83:868-876.

Question 46

After trial placement of components in a primary total knee arthroplasty, the knee is unable to come to full extension, but the flexion gap is appropriately balanced. After adequate soft-tissue releases have been performed, what is the most appropriate next action to balance the reconstruction?

1. Use a larger femoral component
2. Use a thinner polyethylene insert
3. Add posterior femoral augments
4. Resect more proximal tibia
5. Resect additional distal femur

Answer 46

PREFERRED RESPONSE: 5

DISCUSSION: The reconstruction requires additional resection of the distal femur to allow increased extension while maintaining the current flexion gap tension. Resecting more proximal tibia or decreasing the tibial polyethylene thickness will decrease flexion tension as well as extension tension. Adding posterior femoral augments and using a larger femoral component will increase flexion tension.

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

Carey CT, Tria AJ Jr: Surgical principles of total knee replacement: Incisions, extensor mechanism, ligament balancing, in Pellicci PM, Tria AJ Jr, Garvin KL, eds: Orthopaedic Knowledge Update: Hip and Knee Reconstruction, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 281-286.

Question 47

During total knee arthroplasty, the patella is noted to subluxate laterally despite a lateral retinacular release. Which of the following methods is most likely to improve patellar stability?

1. Slight external rotation of the tibial component
2. Slight internal rotation of the femoral component
3. Slight anterior translation of the tibial component
4. Use of a fixed-bearing knee as opposed to a mobile-bearing knee
5. Use of a thicker patellar component

Answer 47

PREFERRED RESPONSE: 1

DISCUSSION: Slight external rotation of the tibial component will cause a net medialization of the tibial tubercle during knee articulation. This will help centralize the extensor mechanism over the trochlear groove and minimize the tendency for lateral subluxation. Internal rotation of the femoral component increases the risk of patellar instability. Anterior translation of the tibial component moves the patellar tendon insertion posteriorly, and may increase force on the patella but should not substantially alter patellar tracking. Clinical studies have shown no patellofemoral benefits to the use of fixed- or mobile-bearing designs. Thicker patellar components will not improve tracking, and may compound the problem.

Nelson C, Lombardi PM, Pellicci PM: Hybrid total hip replacement, in Pellicci PM, Tria AJ Jr, Garvin KL, eds: Orthopaedic Knowledge Update: Hip and Knee Reconstruction, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, p 207.

Pagnano MW, Trousdale RT, Stuart MJ, et al: Rotating platform knees did not improve patellar tracking: A prospective, randomized study of 240 primary total knee arthroplasties. Clin Orthop 2004;428:221-227.

Lotke PA, Garino JP, eds: Revision Total Knee Arthroplasty. Philadelphia PA, Lippincott-Raven, 1999, pp 427-435.

Mulvey TJ, Thornhill TS, Kelly MA, Healy WL: Complications associated with total knee arthroplasty, in Pellicci PM, Tria AJ Jr, Garvin KL, eds: Orthopaedic Knowledge Update: Hip and Knee Reconstruction, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 323-337.

Question 48

A 73-year-old man has stiffness after undergoing primary posterior cruciate ligament-retaining total knee arthroplasty 18 months ago. Extensive physiotherapy, dynamic splinting, and manipulations under anesthesia have failed to result in improvement. Examination reveals range of motion from 30° to 60° of flexion. The components are well fixed, and the evaluation for infection is negative. In discussing the possibility of revision arthroplasty, the patient should be advised that

1. the success of improving range of motion to a functional range of 0° to 90° in the literature is between 75% to 80%.
2. the preoperative arc of motion will not influence the ultimate range of motion after formal component revision.
3. change from a posterior cruciate ligament-retaining to a posterior cruciate ligament-substituting design has a much greater chance of success.
4. manipulation under anesthesia will effectively improve range of motion if postoperative stiffness develops following revision.
5. the major postoperative focus will be to regain near-full extension.

Answer 48

PREFERRED RESPONSE: 5

DISCUSSION: Stiffness following primary total knee arthroplasty remains a vexing problem. Treatment options have included extensive physical therapy, dynamic splinting, manipulation under anesthesia, arthroscopic arthrolysis, open arthrolysis with polyethylene exchange, and ultimately revision arthroplasty. Results are not as gratifying as would be expected. Babis and associates performed an open arthrolysis and polyethylene exchange on seven patients who were followed for a mean of 4.2 months. The results were poor. The mean improvement in arc of motion was only 20°. Nicholls and Dorr treated 13 patients for stiffness. Only 40% of those patients obtained good to excellent results. Four patients (30%) required manipulation because of recurrent stiffness postoperatively. They noted they could not predictably improve the arc of motion with a revision operation. Haidukewych and associates reported on 15 patients who underwent revision of well-fixed components after total knee arthroplasty for stiffness. Of the 15 patients, 10 (66%) were satisfied with the outcome revision. Interestingly, they noted that in patients for whom the total arc of motion did not improve but who regained near-full extension, there was a greater amount of satisfaction with the procedure than for those who did not regain full extension.

Babis GC, Trousdale RT, Pagnano MW, et al: Poor outcomes of isolated tibial insert exchange and arthrolysis for the management of stiffness following total knee arthroplasty. J Bone Joint Surg Am 2001;83:1534-1536.

Nicholls DW, Dorr LD: Revision surgery for stiff total knee arthroplasty. J Arthroplasty 1990;5:S73-S77.

Haidukewych GJ, Jacofsky DJ, Pagnano MW, et al: Functional results after revision of well-fixed components for stiffness after primary total knee arthroplasty. J Arthroplasty 2005;20:133-138.

Question 49

A 62-year-old patient is seen for routine follow-up after undergoing cementless total hip arthroplasty 2 years ago. The patient reports limited range of motion that severely affects daily activities. A radiograph is shown in Figure 29. Management should now consist of

1. observation only.
2. NSAIDs and protected weight bearing.
3. irradiation to the affected area.
4. surgical excision.
5. surgical excision and postoperative irradiation.

Answer 49

PREFERRED RESPONSE: 5

DISCUSSION: The patient has symptomatic postoperative heterotopic ossification after total hip arthroplasty. Postoperative prophylactic treatments include NSAIDs (usually indomethacin) or low-dose irradiation. The heterotopic ossification shown here is quite mature; therefore, nonsurgical management will not be successful. Surgical excision of grade III or IV heterotopic ossification should be followed with postoperative irradiation to minimize the chances of recurrence.

Ayers DC, Evarts CM, Parkinson JR: The prevention of heterotopic ossification in high-risk patients by low-dose radiation therapy after total hip arthroplasty. J Bone Joint Surg Am 1986;68:1423-1430.

Healy WL, Lo TC, DeSimone AA, et al: Single-dose irradiation for the prevention of heterotopic ossification after total hip arthroplasty: A comparison of doses of five hundred and fifty and seven hundred centigray. J Bone Joint Surg Am 1995;77:590-595.

Question 50

What bilateral surgical intervention is considered inappropriate based on the findings shown in the radiograph in Figure 30?

1. Vascularized fibular graft
2. Proximal femoral osteotomy
3. Core decompression
4. Hip arthrodesis
5. Femoral resurfacing

Answer 50

PREFERRED RESPONSE: 4

DISCUSSION: The radiograph reveals osteonecrosis of both femoral heads with reasonably maintained joint surfaces. There may be some slight flattening of the femoral heads. Hip arthrodesis is difficult to perform because of the necrotic bone. Its use in patients with osteonecrotic hips is limited because of the 80% bilaterality; therefore, it is not an acceptable alternative. All the other options are acceptable interventions.

Mont MA, Jones LC, Sotereanos DG, et al: Understanding and treating osteonecrosis of the femoral head. Instr Course Lect 2000;49:169-185.

Barrack R, Berry D, Burak C, et al: Hip and pelvis reconstruction, in Koval KJ, ed: Orthopaedic Knowledge Update, ed 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 417-451.