3. Adult Reconstruction (Hip & Knee) MCQs

A patient presents with pain and swelling 5 years after receiving a primary total hip arthroplasty with a large-diameter cobalt-chromium head on a titanium stem. Workup reveals a solid pseudotumor but no infection. What is the primary mechanism of failure?

While highly cross-linking polyethylene significantly improves wear characteristics in total hip arthroplasty, it negatively alters the material's mechanical properties. Which of the following is decreased as a direct result of the irradiation process?

What is the primary advantage of highly cross-linked polyethylene compared to conventional polyethylene in total hip arthroplasty (THA)?

During a posterior-stabilized TKA, trial reduction reveals the knee is tight in flexion but well-balanced and symmetric in extension. What is the most appropriate next step to balance the knee?

A 65-year-old woman complains of a painful popping sensation in her knee 9 months after a posterior-stabilized TKA. The pop occurs as she extends the knee from 40 degrees to full extension. What is the most likely cause?

Following a primary THA using a posterior approach, a patient exhibits foot drop and an inability to actively dorsiflex the ankle. Eversion of the foot is also weak, but ankle inversion is normal. Which branch of the sciatic nerve is most likely injured, and what is its most common mechanism of injury?

A 55-year-old man with a metal-on-metal total hip arthroplasty presents with groin pain and a palpable anterior mass 4 years postoperatively. Radiographs show a well-fixed implant with normal alignment. Serum cobalt and chromium levels are significantly elevated. Aspiration yields sterile, cloudy fluid. What is the most appropriate definitive management?

A 68-year-old woman experiences her third posterior dislocation of her THA within 6 months. Radiographs demonstrate a well-fixed acetabular component with 55 degrees of abduction and 0 degrees of anteversion. The femoral stem is well-fixed with 15 degrees of anteversion. What is the most appropriate surgical intervention?

Which of the following preoperative findings is the most absolute contraindication for a standard mobile-bearing medial unicompartmental knee arthroplasty (UKA)?

A 75-year-old male presents with new-onset swelling and pain 12 years after a primary TKA. Radiographs show eccentric joint space narrowing but well-fixed components with no osteolysis. Aspiration is negative for infection. What is the most appropriate treatment?

A patient with a conventional metal-on-polyethylene THA presents 5 years postoperatively with vague hip pain and a mass. MRI with metal suppression reveals a cystic lesion surrounding the hip joint. Aspiration reveals dark fluid with high cobalt and chromium levels. What is the most likely source of the metal wear?

You are performing a TKA on a severe valgus knee. After making the standard bony cuts, the knee remains tight laterally in extension but balanced in flexion. Which structure is typically released first to balance the extension gap?

Modern cementing techniques for total hip arthroplasty (third-generation) have significantly improved the survivorship of the femoral stem. Which of the following is a core component of third-generation cementing technique?

When establishing correct femoral component rotation in a TKA, the anterior-posterior (AP) axis (Whiteside's line) is commonly used. To what reference line should Whiteside's line be strictly perpendicular?

An 80-year-old woman requires revision THA for severe aseptic loosening. Radiographs demonstrate a fracture through the acetabular fossa separating the superior and inferior halves of the hemipelvis. What is the most definitive surgical construct to achieve stable fixation in this setting?

During a posterior-stabilized total knee arthroplasty, the trial reduction demonstrates a balanced and symmetric extension gap, but the flexion gap is unacceptably tight. Which of the following is the most appropriate intraoperative adjustment to balance the gaps?

A 45-year-old active man undergoes a total hip arthroplasty with a ceramic-on-ceramic bearing surface. What is a specific, known potential complication associated with this bearing surface compared to metal-on-polyethylene?

A 65-year-old man presents with acute onset knee pain and swelling 3 weeks after an uncomplicated primary total knee arthroplasty. Knee aspiration yields a white blood cell count of 35,000 cells/uL with 90% polymorphonuclear leukocytes. What is the most appropriate management?

Following the implantation of total knee arthroplasty components, trial reduction reveals lateral patellar subluxation. The components are correctly sized. Which of the following component malrotations is the most likely cause?

A 55-year-old woman with a metal-on-metal total hip arthroplasty presents with unexplained groin pain 4 years postoperatively. Her ESR and CRP are normal, but an MRI with metal artifact reduction sequence (MARS) shows a large, expanding solid/cystic mass around the joint. What is the recommended next step?