3. Adult Reconstruction (Hip & Knee) MCQs

A 42-year-old female complains of localized anterior groin pain 1 year following an uncemented THA. The pain is worst when actively lifting her leg to get into a car or actively performing a straight leg raise. A diagnostic injection of local anesthetic into the iliopsoas bursa provides complete, temporary relief. Which acetabular component factor is the most likely structural cause of this complication?

A 65-year-old man undergoes a primary total hip arthroplasty. During trialing, the surgeon decides to increase the femoral offset by 10 mm compared to the patient's native anatomy, while keeping the leg length unchanged. What is the expected biomechanical effect of this modification?

Figure 1 shows the radiograph of a 58-year-old man presenting with insidious onset of progressive groin pain 5 years after an uncomplicated, metal-on-polyethylene total hip arthroplasty. Radiographs show a well-fixed, uncemented stem and cup without evidence of osteolysis. Laboratory workup reveals a serum cobalt level of 14.5 ppb and a serum chromium level of 1.2 ppb. A MARS MRI demonstrates a large, thick-walled cystic periarticular collection. What is the most likely diagnosis?

A 70-year-old woman complains of a painful total hip arthroplasty that was performed 2 years ago. The pain has been constant for the past 6 months. Hip aspiration yields synovial fluid with a white blood cell count of 4,800 cells/µL and 80% polymorphonuclear leukocytes. An alpha-defensin test is positive. ESR is 55 mm/h, and CRP is 32 mg/L. According to MSIS criteria, the patient has a periprosthetic joint infection (PJI). What is the most appropriate surgical management?

A 72-year-old woman requires a revision THA for aseptic loosening. Intraoperative assessment, confirming findings on preoperative radiographs (Figure 2), demonstrates a mobile pelvic discontinuity with limited but viable remaining host bone and an intact posterior column structurally. Which of the following reconstructive options provides the most reliable long-term stability and biologic fixation?

A surgeon utilizes the direct anterior approach for a primary total hip arthroplasty. To avoid denervating the tensor fasciae latae (TFL) during deep dissection and retractor placement, the surgeon must protect its nerve supply. Which nerve supplies the TFL, and where is it at greatest risk during this approach?

Figure 3 shows the radiograph of an 82-year-old woman who sustained a fall 10 years after a cemented total hip arthroplasty. The radiograph reveals a periprosthetic spiral fracture around the stem tip. The stem has subsided by 5 mm compared to previous films, and there is a radiolucent line surrounding the cement mantle. The patient has good proximal femoral bone stock. Based on the Vancouver classification, what is the most appropriate management?

A 55-year-old woman presents with vague groin pain and a palpable soft tissue fullness in the groin 6 years after undergoing a metal-on-metal THA. Her serum cobalt levels are elevated at 15 ppb. Conventional radiographs demonstrate well-fixed components with no evidence of osteolysis.

What is the most appropriate next step in the diagnostic workup to evaluate for an adverse local tissue reaction (ALTR)?

An 82-year-old woman falls and sustains a periprosthetic femur fracture around a cemented polished taper-slip stem.

Radiographs demonstrate a fracture at the tip of the stem. The cement mantle is fractured, and the stem has subsided 3 cm. The proximal femoral bone stock remains adequate. According to the Vancouver classification, what is the most appropriate definitive management?

A surgeon is performing a primary THA utilizing the direct anterior approach (DAA). To minimize the risk of injury to the lateral femoral cutaneous nerve (LFCN), the superficial internervous plane is developed between the tensor fasciae latae (TFL) and the sartorius. During the approach, understanding the variable anatomy of the LFCN is critical. The main trunk of the LFCN most typically crosses the inguinal ligament at what anatomic location?

A 60-year-old woman complains of new-onset anterior groin pain 6 months following an uncomplicated cementless THA. The pain is worst when lifting her leg to get into a car and is reproduced by an active straight leg raise. Cross-table lateral radiographs reveal the anterior edge of the acetabular cup protruding 8 mm beyond the anterior acetabular rim.

What is the most appropriate initial treatment?

A 45-year-old highly active man underwent a ceramic-on-ceramic (CoC) THA. Two years postoperatively, he presents complaining of a highly audible squeaking noise coming from his hip during the swing phase of gait. He denies any hip pain. Which of the following is the most significant biomechanical risk factor associated with squeaking in CoC bearings?

A 55-year-old female presents with persistent, severe lateral right hip pain. She has failed 12 months of conservative management for presumed greater trochanteric pain syndrome. Examination reveals a positive Trendelenburg sign.

MRI demonstrates a full-thickness tear of the gluteus medius tendon with 2 cm of retraction and minimal fatty infiltration (Goutallier grade 1) of the muscle belly. What is the most appropriate next step in management?

A 62-year-old male presents with new-onset groin pain 6 years after a primary total hip arthroplasty. Operative records indicate he received a titanium stem, a cobalt-chromium head, and a highly cross-linked polyethylene liner. Radiographs show a well-fixed stem and cup with no osteolysis. Labs demonstrate an ESR of 12 mm/hr and a CRP of 0.4 mg/dL. Synovial aspirate yields a WBC of 600 cells/µL with 30% polymorphonuclear leukocytes. Metal ion testing reveals an elevated serum cobalt (14 ppb) and a normal chromium (1.2 ppb) level. MARS MRI demonstrates a cystic pseudotumor adjacent to the joint. What is the most likely source of the problem?

A surgeon utilizes the modified Hardinge (anterolateral) approach for a primary total hip arthroplasty. During the surgical exposure, the anterior portion of the abductor mechanism is detached from the greater trochanter. Injury to which of the following nerves is the most recognized neurological complication if the proximal split in the muscle belly extends too far superiorly?

An 82-year-old female sustains a fall and presents with severe thigh pain. She underwent a cementless total hip arthroplasty 10 years ago. Radiographs demonstrate a displaced spiral fracture around the tip of the femoral stem. Comparison with prior radiographs indicates the femoral component has subsided 15 mm and is in varus. Based on the Vancouver classification, what is the most appropriate surgical management?

During preoperative planning for a primary total hip arthroplasty in a patient with significant coxa vara, the surgeon decides to use a high-offset femoral stem. Compared to a standard-offset stem, what is the primary biomechanical advantage of increasing femoral offset?

A 68-year-old male presents with persistent right hip pain 3 years after a primary total hip arthroplasty. Serum CRP is 18 mg/L and ESR is 45 mm/hr. A diagnostic hip aspiration yields frankly purulent synovial fluid. The synovial fluid WBC count is 15,000 cells/µL with 88% neutrophils. Based on the 2018 International Consensus Meeting (ICM) criteria, what is the next appropriate step in diagnostic management?

A 25-year-old male undergoes a surgical dislocation of the hip to treat a complex head-neck deformity (cam impingement). To preserve the primary blood supply to the femoral head, the surgeon must be meticulously careful to protect the profound branch of the medial femoral circumflex artery (MFCA). This critical vessel typically runs immediately posterior to which of the following structures?