3. Adult Reconstruction (Hip & Knee) MCQs

A 60-year-old man presents with an inability to actively extend his knee 3 months after a primary total knee arthroplasty. Ultrasound confirms a massive, chronic disruption of the quadriceps tendon with significant tissue retraction. He has failed nonoperative management with a brace. What is the most reliable surgical reconstruction method for this chronic defect?

A 71-year-old woman is undergoing a two-stage exchange arthroplasty for a chronic periprosthetic joint infection of her knee. Six weeks after removal of components, debridement, and placement of an articulating antibiotic spacer, she completes her IV antibiotic course. Two weeks off antibiotics, her knee is warm, erythematous, and a synovial aspirate reveals 60,000 WBC/mcL. What is the most appropriate next step in management?

During a posterior approach to the hip for total hip arthroplasty, a sequence of short external rotators is identified and tagged for later repair. Which muscle in this region should be carefully preserved or partially released to protect the underlying sciatic nerve from direct surgical trauma?

A 65-year-old asymptomatic woman returns for a 3-year follow-up after a primary total hip arthroplasty using a fully porous-coated cementless femoral stem. Radiographs demonstrate focal loss of cortical bone density and radiolucencies specifically in Gruen zones 1 and 7, while the distal stem appears rigidly fixed. What is the most likely etiology of these radiographic findings?

A 65-year-old man who underwent a primary total knee arthroplasty 4 weeks ago presents with a 3-day history of acute fever, severe knee pain, and swelling. Aspiration reveals synovial fluid with 65,000 WBCs/uL and 95% neutrophils. What is the most appropriate management?

A 70-year-old woman complains of recurrent knee swelling and a feeling of giving way when descending stairs, 2 years after a primary TKA. Range of motion is 0 to 120 degrees. Examination reveals a stable knee in full extension, but significant varus, valgus, and anteroposterior laxity at 90 degrees of flexion. What is the most likely cause of this instability?

A 62-year-old woman complains of groin pain 1 year after an uncomplicated THA. The pain is worst when getting out of a car and actively lifting her leg into bed. Resisted active hip flexion reproduces the pain. Radiographs show the acetabular component in 40 degrees of abduction and 20 degrees of anteversion, but the anterior rim protrudes 4 mm beyond the anterior acetabular wall. What is the most appropriate initial treatment?

A 78-year-old man presents with thigh pain and inability to bear weight after a mechanical fall. He has an uncemented THA placed 12 years ago. Radiographs demonstrate a displaced fracture around the femoral stem. The stem has subsided by 2 cm, and there is severe proximal femoral osteolysis with complete loss of the calcar. What is the most appropriate treatment?

A 55-year-old man presents with increasing groin pain 6 years after a metal-on-polyethylene THA with a 36-mm cobalt-chromium femoral head on a titanium stem. Blood tests reveal an elevated serum cobalt level and a normal chromium level. MRI with metal artifact reduction sequence (MARS) reveals a cystic mass in the hip abductors. What is the most likely diagnosis?

A 65-year-old woman reports anterior knee pain and frequent subluxation of her patella 1 year following a primary TKA. Clinical examination demonstrates severe patellar apprehension and lateral tracking. A CT scan to evaluate component position is most likely to show which of the following?

According to the Musculoskeletal Infection Society (MSIS) criteria, which of the following findings is considered a major criterion, confirming a definitive diagnosis of a periprosthetic joint infection?

A 68-year-old woman is undergoing revision THA for severe aseptic loosening. Intraoperatively, the superior and inferior halves of the acetabulum are found to move independently. Which of the following is the most appropriate management strategy for the acetabulum?

A 60-year-old man sustained a posterior dislocation of his primary THA 3 weeks postoperatively while bending over. Closed reduction was successful. Radiographs demonstrate the acetabular cup is positioned in 10 degrees of anteversion and 40 degrees of abduction. The femoral stem is in 5 degrees of retroversion. What is the primary cause of his dislocation?

A 65-year-old man undergoes aspiration of a painful THA 2 years after surgery. The synovial fluid shows a WBC count of 45,000 cells/uL with 90% neutrophils. Aerobic and anaerobic cultures are negative at 5 days. Due to high suspicion, cultures are held longer, and at 12 days yield a gram-positive, anaerobic rod. What is the most likely pathogen?

A 45-year-old man who underwent a ceramic-on-ceramic THA 3 years ago complains of a high-pitched squeaking noise coming from his hip when walking. He denies pain. Radiographs show a well-fixed cup in 60 degrees of abduction and a well-fixed stem. What is the most likely etiology of the squeaking?

A 65-year-old man presents with chronic right knee pain 2 years after a primary TKA. ESR is 45 mm/hr and CRP is 2.5 mg/dL. Aspiration yields 4,500 WBCs/mcL with 85% neutrophils. Cultures are negative at 7 days. Which of the following synovial fluid biomarkers would be most specific to confirm a periprosthetic joint infection?

A 72-year-old woman experiences her third posterior dislocation 4 months after a primary right THA performed via a posterior approach. Radiographs show the acetabular component is in 30 degrees of inclination and 5 degrees of retroversion. The femoral stem is stable and in 15 degrees of anteversion. What is the most appropriate surgical intervention?

A 68-year-old woman complains of a painful catching sensation in her anterior knee when extending from a flexed position, 1 year after a posterior-stabilized TKA. On examination, a palpable "clunk" is felt at 35 degrees of flexion as the knee actively extends. Radiographs show well-fixed components with no evidence of loosening. What is the most likely diagnosis?

A 55-year-old man presents with right groin pain and a palpable anterior mass 6 years after a metal-on-polyethylene THA with a large-diameter cobalt-chrome femoral head. Laboratory studies show an ESR of 10 mm/hr, CRP of 0.4 mg/dL, and elevated serum cobalt levels with normal chromium. What is the most likely cause of his symptoms?