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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 248 of 326

This practice set contains high-yield board review questions covering key concepts in 3. Adult Reconstruction (Hip & Knee). Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 4941

Topic: 3. Adult Reconstruction (Hip & Knee)

A 40-year-old man with a history of Legg-Calve-Perthes disease underwent a right hip resurfacing 3 years ago with no perioperative complications. He has developed hip pain gradually during the last 4 months.Radiographs show no evidence of fixation loosening or any adverse changes at the femoral neck. There is no periarticular osteolysis.

What is the most appropriate management of this condition?

. Continue to observe with repeat radiographs in 6 months.
. Fluoroscopic-guided iliopsoas tendon cortisone injection
. Hip aspiration
. Serum cobalt and chromium levels and metal-reduction MRI scan

Correct Answer & Explanation

. Continue to observe with repeat radiographs in 6 months.

Explanation

Controversies remain with regard to the best approach for treating patients with metal-on-metal (MOM) hip arthroplasties. All patients with painful MOM hip arthroplasties should be examined for fixation loosening, wear/osteolysis, and infection no differently than patients with non-MOM hip arthroplasties.Obtaining serum trace element levels is recommended. If the levels are high, cross-sectional imaging should be obtained to determine if there is any pseudotumor or tissue necrosis around the hip arthroplasty.Hip aspiration should be considered if there is concern for infection and if erythrocyte sedimentation rate and C-reactive protein are elevated. Aseptic lymphocytic vasculitis-associated lesions have been identified as occurring around MOM hip arthroplasties. Histologic features are predominantly tissue necrosis with infiltration of lymphocytes and plasma cells.

Question 4942

Topic: 3. Adult Reconstruction (Hip & Knee)

A 40-year-old man with a history of Legg-Calve-Perthes disease underwent a right hip resurfacing 3 years ago with no perioperative complications. He has developed hip pain gradually during the last 4 months.Radiographs show no evidence of fixation loosening or any adverse changes at the femoral neck. There is no periarticular osteolysis.

The patient developed a large intra-articular and intrapelvic pseudotumor. What predominant histological features are present in such a lesion?

. Polymorphonuclear leukocytes
. Extracellular metal-wear debris
. Cement particles within the macrophages
. Lymphocytes and plasma cells

Correct Answer & Explanation

. Polymorphonuclear leukocytes

Explanation

Controversies remain with regard to the best approach for treating patients with metal-on-metal (MOM) hip arthroplasties. All patients with painful MOM hip arthroplasties should be examined for fixation loosening, wear/osteolysis, and infection no differently than patients with non-MOM hip arthroplasties.Obtaining serum trace element levels is recommended. If the levels are high, cross-sectional imaging should be obtained to determine if there is any pseudotumor or tissue necrosis around the hip arthroplasty.Hip aspiration should be considered if there is concern for infection and if erythrocyte sedimentation rate and C-reactive protein are elevated. Aseptic lymphocytic vasculitis-associated lesions have been identified as occurring around MOM hip arthroplasties. Histologic features are predominantly tissue necrosis with infiltration of lymphocytes and plasma cells.

Question 4943

Topic: 3. Adult Reconstruction (Hip & Knee)
What has been identified as a risk factor for total knee arthroplasty failure after previous high tibial osteotomy?
. Body mass index higher than 35
. Female gender
. Preoperative stiffness
. Advanced age

Correct Answer & Explanation

. Body mass index higher than 35

Explanation

Increased weight, male gender, young age at the time of total knee arthroplasty, laxity, and limb malalignment preoperatively have been identified as risk factors for early failure for total knee arthroplasty following high tibial osteotomy.

Question 4944

Topic: 3. Adult Reconstruction (Hip & Knee)
A 70-year-old woman with a body mass index (BMI) of 34 and a history of hypercholesterolemia has elected to undergo total hip arthroplasty. Her son recently learned he has Factor V Leiden following an episode of pulmonary embolism. What are this patient’s risk factors for thromboembolic disease?
. Type of surgery, age, and BMI
. Type of surgery, hypercholesterolemia, and age
. Age, BMI, and hypercholesterolemia
. BMI, type of surgery, and hypercholesterolemia

Correct Answer & Explanation

. Type of surgery, age, and BMI

Explanation

Risk stratification is one of the most critical clinical evaluations before undergoing total joint arthroplasty. Many factors have been identified to increase risk for venous thromboembolism (VTE). The major factors include previous VTE, obesity, type of surgery (such as total joint arthroplasty), hypercoagulable states, myocardial infarction, congestive heart failure, family history of VTE, and hormonal replacement therapy. Hypercholesterolemia is not a risk factor for thromboembolic disease.

Question 4945

Topic: 3. Adult Reconstruction (Hip & Knee)

An otherwise healthy 79-year-old man underwent a total hip arthroplasty 5 years ago. He has had a 48-hour history of groin and thigh pain and malaise. Examination reveals pain with internal motion of thehip. Radiographs show well-fixed, appropriately positioned components.

What serum inflammatory marker has the highest correlation with periprosthetic joint infection?

. C-reactive protein
. Serum white blood cell count
. Erythrocyte sedimentation rate
. Interleukin 6 (IL-6)

Correct Answer & Explanation

. C-reactive protein

Explanation

Although CRP and ESR can be elevated in the setting of infection, IL-6 has been shown to have the highest correlation with infection. Serum white blood cell count has been shown to be ineffective in correlating with periprosthetic joint infection. Given the history, it is likely this patient has an acute hematogenous infection. Appropriate steps including initiation of intravenous antibiotics after cultures have been obtained and medical optimization with treatment consisting of irrigation and debridement with head and liner exchange. There is no role for an indium scan or a repeat aspiration in the presence of an elevated ESR, CRP, and IL-6. There is no role for arthroscopic debridement in this case.

Question 4946

Topic: 3. Adult Reconstruction (Hip & Knee)

An otherwise healthy 79-year-old man underwent a total hip arthroplasty 5 years ago. He has had a 48-hour history of groin and thigh pain and malaise. Examination reveals pain with internal motion of thehip. Radiographs show well-fixed, appropriately positioned components.

Serum blood work reveals markedly elevated erythrocyte sedimentation rate (ESR), C-reactive protein(CRP), and IL-6 levels. Cultures from a hip aspirate reveal a low virulence staph epidermis. What is the next appropriate step in management?

. Arthroscopic debridement
. Reaspiration to confirm that the organism is not a contaminant
. Indium scan to evaluate for infection
. Irrigation and debridement and head and liner exchange

Correct Answer & Explanation

. Arthroscopic debridement

Explanation

Although CRP and ESR can be elevated in the setting of infection, IL-6 has been shown to have the highest correlation with infection. Serum white blood cell count has been shown to be ineffective in correlating with periprosthetic joint infection. Given the history, it is likely this patient has an acute hematogenous infection. Appropriate steps including initiation of intravenous antibiotics after cultures have been obtained and medical optimization with treatment consisting of irrigation and debridement with head and liner exchange. There is no role for an indium scan or a repeat aspiration in the presence of an elevated ESR, CRP, and IL-6. There is no role for arthroscopic debridement in this case.

Question 4947

Topic: Total Knee Arthroplasty (TKA)
A 70-year-old man complains of symptomatic medial knee pain that has become progressively worse during the past year. An MRI scan reveals a complex posterior horn medial meniscus tear with associated medial and patellofemoral cartilage defects. Radiographs reveal medial joint space narrowing and osteophytes in the other compartments. What treatment is most likely to provide long-term, durable symptom relief?
. High tibial osteotomy
. Total knee replacement
. Unicondylar knee replacement
. Arthroscopic partial meniscectomy

Correct Answer & Explanation

. Total knee replacement

Explanation

Total knee replacement is a well-established surgery for diffuse, symptomatic osteoarthritis of the knee joint, and its efficacy has been shown in many studies. According to the 2008 AAOS Clinical Practice Guideline, Treatment of Osteoarthritis of the Knee, arthroscopy in the setting of existing osteoarthritis is efficacious for relieving the signs and symptoms of a torn meniscus, but not osteoarthritis. Likewise, in young and active patients, clinical outcomes show improvement after realignment osteotomy for single-compartment osteoarthritis. Unicondylar knee replacement is not indicated for tricompartmental disease of the knee.

Question 4948

Topic: 3. Adult Reconstruction (Hip & Knee)
A 68-year-old man reports hip pain 15 years after successful cementless total hip arthroplasty. Radiographs show 3 mm of linear wear of the modular acetabular liner and a retro-acetabular osteolytic lesion. Both the titanium femoral and acetabular components appear to be well fixed. The orthopaedic surgeon recommends revision of the acetabular liner and femoral head. This patient is at increased risk for
. dislocation.
. periprosthetic fracture.
. infection.
. progressive osteolysis.

Correct Answer & Explanation

. dislocation.

Explanation

Isolated acetabular liner revision is frequently performed in cases of liner wear and periprosthetic osteolysis in the absence of acetabular component loosening. Many reports have documented an increased incidence of dislocation following this type of revision surgery. This dislocation rate can be reduced by using a larger-diameter femoral head at the time of revision. If the acetabular component is loose or malpositioned, it should be revised. If the locking mechanism is damaged, then a replacement liner may be cemented into the well-fixed shell. Numerous studies have shown that many osteolytic lesions will reduce in size or heal without bone grafting, and removal of the source of wear debris will arrest the progression of osteolysis. The risk for periprosthetic fracture and infection are lower than risk for dislocation in this setting.

Question 4949

Topic: 3. Adult Reconstruction (Hip & Knee)
A 61-year-old man with a body mass index of 31 had a 6-month gradual onset of right medial knee pain. Examination revealed a small effusion, stable ligaments, a normally tracking patella, and mild medial joint line tenderness. Standing radiographs show mild medial joint space narrowing. Effective treatment at this stage of early medial compartmental osteoarthritis includes
. glucosamine 1500 mg/day and chondroitin sulfate 800 mg/day.
. weight loss through dietary management and low-impact aerobic exercises.
. arthroscopic debridement and lavage.
. a valgus-directing brace.

Correct Answer & Explanation

. weight loss through dietary management and low-impact aerobic exercises.

Explanation

According to the 2008 AAOS Clinical Practice Guideline, Treatment of Osteoarthritis of the Knee (Non-Arthroplasty), Level 1 evidence confirms that weight loss and exercise benefit patients with knee osteoarthritis. The other responses have either inclusive evidence (a valgus-directing brace) or no evidence to support their use (glucosamine 1500 mg/day and chondroitin sulfate 800 mg/day and arthroscopic debridement and lavage).

Question 4950

Topic: 3. Adult Reconstruction (Hip & Knee)
A 63-year-old man had right groin pain 18 months after undergoing an uncemented right total hip replacement using a modular femoral neck implant and a metal-on-polyethylene bearing. His laboratory studies revealed an erythrocyte sedimentation rate of 8 mm/h (reference range, 0-20 mm/h) and C-reactive protein level of 5.4 mg/L (reference range, 0.08-3.1 mg/L). A preoperative aspiration revealed cultures that were negative for infection. A cell could not be obtained for evaluation because the cells were “degenerative.” At the time of surgery the joint fluid was turbid in appearance; the periarticular tissues appeared avascular and tan/beige in color. An intraoperative frozen section was negative for acute inflammation. The implants were solidly fixed to bone. The cause of this patient’s symptoms and the intraoperative findings most likely are attributable to
. “backside” polyethylene wear.
. metal debris.
. soft-tissue sarcoma.
. iliopsoas tendonitis.

Correct Answer & Explanation

. metal debris.

Explanation

Metal debris has caused an adverse local soft-tissue response in this scenario. The laboratory studies are all negative for infection. The MRI scan shows a large soft-tissue mass that is posterior to the hip and originating from the hip joint. The dysvascular appearance of the tissues is typical for an adverse tissue response to metal. Even though the bearing is polyethylene, the modular junctions created sufficient metal debris to cause the reaction. The other diagnoses are not consistent with this clinical presentation.

Question 4951

Topic: 3. Adult Reconstruction (Hip & Knee)

The range of knee mobility after total knee replacement is multifactorial and dependent upon implant design, surgical implantation accuracy, and patient-specific variables. What total knee implant design is associated with the most knee flexion after total knee replacement?

. Highly conforming articular surface geometry
. Higher-flexion femoral component design manufactured to allow the most knee flexion
. Posterior cruciate-stabilized implant, with or without a higher flexion manufacturing modification
. Posterior cruciate-retaining design with a mobile bearing, custom implanted based on CT scan Data

Correct Answer & Explanation

. Highly conforming articular surface geometry

Explanation

A posterior cruciate-stabilized implant has the best support in the literature in terms of the most favorable range of motion after knee arthroplasty, regardless of whether the femoral component is designed with a higher flexion variation. The higher flexion design is a manufacturing variation that is intended to increase motion by clearing the posterior condyles in flexion. Although the knee may not gain more flexion, this design allows for more safety in deep flexion. The long-term outcomes of increased stresses on the polyethylene are not known, however. By itself, a higher-flexion design does not lead to increased knee mobility. The effects of mobile bearings, custom CT scan-based knee implantation, and highly conforming designs on ultimate knee range of motion are uncertain.

Question 4952

Topic: 3. Adult Reconstruction (Hip & Knee)

What factor is associated with a high risk for developing pseudotumors after metal-on-metal hip resurfacing?

. Large-diameter components
. Age 40 or older for men
. Age 40 or younger for women
. Diagnosis of primary osteoarthritis

Correct Answer & Explanation

. Large-diameter components

Explanation

The recent experience of a large clinical cohort revealed the most likely risk factors as female gender, age younger than 40, small components, and the diagnosis of hip dysplasia causing osteoarthritis. Failure was least likely among men and procedures involving larger components. These data have prompted some authors to caution against use in women and to primarily target candidates who are men younger than age 50. Small components may be more prone to failure because of malpositioning and edge loading, which have been noted to be more common in dysplasia cases.

Question 4953

Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 64 is the radiograph of a 77-year-old woman with a painful total hip arthroplasty (THA) who had surgery 15 years ago. Preoperative laboratory studies reveal a C-reactive protein (CRP) of 4 mg/L (reference range, 0.08-3.1 mg/L). Her serum white blood cell (WBC) count and differential values are within defined limits, and her erythrocyte sedimentation rate (ESR) is 35 mm/h (reference range, 0-20 mm/h). What is the next appropriate step in management of the patient?
. Labeled WBC scan
. MRI scan of the hip to evaluate for fluid collection
. Revision THA with gram stain and multiple cultures
. Aspiration with cell count and differential and culture

Correct Answer & Explanation

. Aspiration with cell count and differential and culture

Explanation

Aspiration is appropriate in the setting of a failed total joint replacement when ESR and CRP are elevated, even with a normal systemic WBC count. A MRI scan of the hip is not useful in this setting. A labeled WBC scan is of no additional value when an aspiration of the hip is planned. Although multiple cultures should be obtained at the time of revision THA, preoperative aspiration is appropriate in this case.

Question 4954

Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 64 is the radiograph of a 77-year-old woman with a painful total hip arthroplasty (THA) who had surgery 15 years ago. Preoperative laboratory studies reveal a C-reactive protein (CRP) of 4 mg/L (reference range, 0.08-3.1 mg/L). Her serum white blood cell (WBC) count and differential values are within defined limits, and her erythrocyte sedimentation rate (ESR) is 35 mm/h (reference range, 0-20 mm/h). At the time of revision THA, the acetabular defect is confined to a contained cavitary defect in the dome. Anterior and posterior columns are intact, as is the rim. What is the most appropriate acetabular reconstruction?
. Bilobed or “double bubble” acetabular component
. Cementless acetabular hemisphere with multiple screws
. Cemented all-polyethylene shell
. Antiprotrusio cage device

Correct Answer & Explanation

. Cementless acetabular hemisphere with multiple screws

Explanation

Aspiration is appropriate in the setting of a failed total joint replacement when ESR and CRP are elevated, even with a normal systemic WBC count. A MRI scan of the hip is not useful in this setting. A labeled WBC scan is of no additional value when an aspiration of the hip is planned. Although multiple cultures should be obtained at the time of revision THA, preoperative aspiration is appropriate in this case. Most acetabular revisions can be accomplished with a cementless hemispherical component. Supplemental fixation with screws is indicated. In this patient, the acetabular rim and columns are intact and the first choice is a cementless hemispherical component. Bilobed components have an unacceptably high failure rate and are not indicated when the acetabular rim is intact. A cemented all-polyethylene shell is not likely to achieve adequate long-term fixation with the sclerotic acetabular bone. An antiprotrusio device is indicated in the setting of severe bone loss or pelvic discontinuity. An antiprotrusio cage is the best choice in the setting of a pelvic discontinuity that has the capacity to heal. If the discontinuity does not have the capacity to heal, it can be treated in distraction with an acetabular allograft supported by a cage or custom triflange component. A large porous cup is not likely to achieve stable fixation and will require removal of more acetabular bone. A cemented acetabular component will not achieve adequate stability or fixation in the absence of additional support. Resection arthroplasty would not be the first choice in a potentially reconstructable situation. The correct choice is a cementless acetabular hemisphere with multiple screws.

Question 4955

Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 64 is the radiograph of a 77-year-old woman with a painful total hip arthroplasty (THA) who had surgery 15 years ago. Preoperative laboratory studies reveal a C-reactive protein (CRP) of 4 mg/L (reference range, 0.08-3.1 mg/L). Her serum white blood cell (WBC) count and differential values are within defined limits, and her erythrocyte sedimentation rate (ESR) is 35 mm/h (reference range, 0-20 mm/h). During the revision, a large anterior column defect secondary to reaming is noted. At the time of impaction of the acetabular component, a loss of resistance is noted and the shell is unstable. After removing the shell, a fracture through the posterior column is noted. What is the most appropriate course of action?
. Resection arthroplasty
. Distraction of the fracture with a large porous acetabular component
. Acetabular antiprotrusio cage with screw fixation
. Revision of the acetabular component with allograft and a cemented socket

Correct Answer & Explanation

. Acetabular antiprotrusio cage with screw fixation

Explanation

In the setting of a pelvic discontinuity (fracture through the posterior column), an antiprotrusio cage is the best choice to provide stability and allow for healing. The cage bridges the discontinuity and provides a stable construct for the acetabular component.

Question 4956

Topic: 3. Adult Reconstruction (Hip & Knee)

a is the radiograph of a 78-year-old woman who has a recent history of increasing thigh pain 12 years after undergoing total hip arthroplasty. Figure 67b is the radiograph after she fell and was unable to ambulate. What is the most appropriate treatment?

---

. Application of a femoral cable plate
. Application of cerclage-wired double allograft femoral struts
. Femoral revision with an uncemented long stem
. Femoral revision with a cemented long-stem prosthesis

Correct Answer & Explanation

. Application of a femoral cable plate

Explanation

Surgical treatment of periprosthetic fractures of total hip replacement with a loose implant and progressive bone loss is associated with a high complication rate. Recent literature would favor the use of long “Wagner-type” stems that have a long distal taper that may optimally engage the remaining femoral shaft isthmus. Plating options are problematic because the ability to use screws with the plate is limited by the intramedullary stem. Use of long distally fixed stems circumvents this problem by enhancing fracture and healing and creating a long-term prosthetic solution in these most difficult cases.

Question 4957

Topic: 3. Adult Reconstruction (Hip & Knee)
What criterion is most reliable when attempting to establish a diagnosis of chronic periprosthetic joint infection (PJI) of the hip and knee?
. Positive bone scan
. Elevated erythrocyte sedimentation rate (ESR)
. Elevated serum white blood cell (WBC) count
. Aspiration with > 2500 WBC per mm3

Correct Answer & Explanation

. Aspiration with > 2500 WBC per mm3

Explanation

Aspiration with a cell count in the joint fluid that yields a WBC higher than 2500 per mm3 is consistent with infection. ESR and C-reactive protein should be obtained when evaluating a patient for PJI. Joint aspiration should be performed for patients being investigated for PJI when CRP and/or ESR values are outside defined limits.

Question 4958

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old man is scheduled to undergo bearing surface revision for wear and osteolysis 10 years after cementless total hip arthroplasty. The femoral head is 28 mm alumina-oxide ceramic material. The components are in good position, and there is no evidence of fixation loosening of either component by radiograph or preoperative bone scan. What outcome is associated with isolated polyethylene exchange?

. Reduced risk for future wear and osteolysis with a larger femoral head
. Reduced risk for future wear and osteolysis with a cobalt chrome femoral head
. Similar risk for dislocation compared to primary total hip arthroplasty
. Increased risk for dislocation compared to primary total hip arthroplasty

Correct Answer & Explanation

. Reduced risk for future wear and osteolysis with a larger femoral head

Explanation

The major complication associated with polyethylene exchange is postoperative dislocation. Maloney and associates noted a dislocation rate of 11% in a study of 35 hips after such revision. Boucher and associates reported a 25% rate of dislocation in a study of 25 patients. Larger femoral heads result in higher volumetric wear in contrast to smaller-diameter heads. Stem revision is not indicated because there is no fixation loosening. Moreover, stem biomaterial has no effect on polyethylene wear.

Question 4959

Topic: 3. Adult Reconstruction (Hip & Knee)
A healthy, active 68-year-old woman had a total hip arthroplasty 3 months ago. She has been to the emergency department with a posterior dislocation 3 times during the last 2 months. Plain radiographs and a CT scan confirm that the acetabular component is oriented in 5 degrees of retroversion and 55 degrees of abduction. What is the most appropriate treatment?
. Revision of the femoral and acetabular components
. Maximizing head-neck ratio and increasing head length
. Acetabular component revision
. Closed reduction with an abduction brace and reinforcement of hip precautions

Correct Answer & Explanation

. Acetabular component revision

Explanation

Acetabular malposition can lead to recurrent instability. When this cause is confirmed, reorientation of the component can lead to successful revision surgery. Revision of the femoral component may not be necessary if the acetabular component is repositioned. Increasing length and maximizing head-neck ratio cannot make up for component malposition. There is no role for nonsurgical treatment in the setting of recurrent instability with component malposition in an active, healthy patient.

Question 4960

Topic: 3. Adult Reconstruction (Hip & Knee)
A 55-year-old woman with history of HIV infection is scheduled for revision total knee arthroplasty to address instability. The index surgery was done 3 years ago. What is the white blood cell (WBC) count threshold in the synovial fluid for an infection diagnosis?
. 100,000
. 25,000
. 2,500
. 250

Correct Answer & Explanation

. 2,500

Explanation

Numerous centers have published data supporting the use of synovial fluid WBC level as one of the most accurate diagnostic criteria for infection in total joint arthroplasty. The threshold ranges between 2000 and 3000 WBC/mL. The sensitivity and specificity have been demonstrated to be higher than 90%.

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