3. Adult Reconstruction (Hip & Knee) MCQs

During a posterior-stabilized total knee arthroplasty, the surgeon uses spacer blocks to assess gap kinematics. With the trial components in place, the extension gap is perfectly symmetric and stable. However, when the knee is flexed to 90 degrees, the joint is grossly unstable both medially and laterally. Which of the following technical errors is the most likely cause of this isolated flexion gap looseness?

During a posterior-stabilized total knee arthroplasty using an anterior referencing system, trial components are inserted. The knee is stable and symmetric in extension, but the flexion gap is unacceptably tight, preventing flexion beyond 90 degrees. What is the most appropriate next step to balance the knee?

A 68-year-old male with a metal-on-polyethylene total hip arthroplasty implanted 5 years ago presents with new-onset groin pain. MRI reveals a large cystic pseudotumor. Aspiration yields cloudy fluid with negative cultures but markedly elevated cobalt and chromium levels. What is the most likely source of the metal debris?

During a primary total knee arthroplasty, the surgeon assesses the gaps and notes the knee is tight in flexion but well-balanced and stable in extension. Which of the following intraoperative maneuvers is most appropriate to balance the knee?

A 65-year-old woman undergoes primary total hip arthroplasty via a posterior approach. Postoperatively, she experiences recurrent posterior dislocations. Radiographic evaluation shows the acetabular component in 45 degrees of abduction and 0 degrees of anteversion. Which of the following revision strategies is most appropriate?

A 62-year-old female with a metal-on-metal total hip arthroplasty presents with groin pain and swelling. Laboratory tests show elevated serum cobalt and chromium levels. MRI reveals a large cystic mass communicating with the joint space. A revision surgery is performed. What is the classic histologic hallmark found in the periprosthetic tissue of this condition?

During a primary total knee arthroplasty in a patient with a severe fixed varus deformity, the surgeon must perform sequential medial releases to balance the knee in extension. After releasing the deep medial collateral ligament (MCL) and removing medial tibial osteophytes, the medial compartment remains tight in extension. What is the next most appropriate anatomic structure to release?

In total joint arthroplasty, the use of highly cross-linked ultra-high-molecular-weight polyethylene (HXLPE) has significantly reduced volumetric wear rates. However, the radiation used to create cross-links also generates free radicals that can cause oxidative degradation. To eliminate these free radicals without compromising the fatigue strength of the polyethylene, manufacturers currently utilize which of the following techniques?

A 68-year-old man who underwent a total hip arthroplasty 5 years ago with a cobalt-chromium head and highly cross-linked polyethylene liner on a titanium stem presents with insidious onset of groin pain. Inflammatory markers are within normal limits. Aspiration yields fluid with 500 WBCs/uL (mostly mononuclear), but serum metal ions show isolated elevated cobalt levels. What is the most likely source of the cobalt?

Ceramic-on-ceramic (CoC) bearing surfaces in total hip arthroplasty are known for excellent wear characteristics. Which of the following is the most commonly cited cause of squeaking in a CoC THA?

A 68-year-old woman is evaluated for a stiff and painful total knee arthroplasty (TKA) 2 years postoperatively. Her range of motion is 10 to 80 degrees. Radiographs show a well-fixed TKA, but the joint line is elevated, and the patella appears significantly inferior to the joint line. Which of the following intraoperative technical errors is the most likely cause of this presentation?

A 60-year-old female presents with progressive groin pain 7 years after undergoing an uncomplicated primary total hip arthroplasty. Her implants consist of a large-diameter cobalt-chromium head on a titanium stem with a highly cross-linked polyethylene liner. Radiographs show well-fixed components with no osteolysis. Laboratory analysis reveals significantly elevated serum cobalt levels with normal serum chromium levels. What is the most likely source of the elevated metal ions?

A 65-year-old man presents with persistent right groin pain 5 years after undergoing a primary metal-on-polyethylene total hip arthroplasty. Aspiration of the hip yields clear fluid with a negative Gram stain and negative cultures. Laboratory workup reveals substantially elevated serum cobalt levels with normal chromium levels. Which of the following is the most likely source of the metal ions?

A 62-year-old man presents with progressive right groin pain and a palpable anterior thigh mass 7 years after undergoing a primary total hip arthroplasty. His implants include a highly cross-linked polyethylene liner, a titanium alloy femoral stem, and a cobalt-chromium femoral head. Serum cobalt levels are 8.5 ppb and chromium is 1.2 ppb. Aspiration of the hip yields synovial fluid with 1,200 WBC/µL and 60% polymorphonuclear leukocytes. Cultures are negative at 7 days. Metal artifact reduction sequence (MARS) MRI demonstrates a large, thick-walled solid and cystic mass compressing the femoral vein. During revision surgery, severe mechanically assisted crevice corrosion (MACC) is noted at the modular head-neck junction. The femoral stem is found to be solidly fixed with no evidence of loosening. Which of the following is the most appropriate definitive management of the femoral side?

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

Figures 3a and 3b show the current radiographs of a 58-year-old man who underwent total knee arthroplasty with a cruciate ligament sparing prosthesis 7 years ago. Examination reveals boggy synovitis and moderate pain, particularly anteriorly. Management should consist of

Which of the following is considered the most predictive factor in determining whether a patient will need a blood transfusion after total knee arthroplasty?

With the increasing availability of total hip arthroplasty (THA) to younger patients with hip osteoarthritis, there has been increased use of alternative bearing surfaces. Compared to a ceramic-on-ceramic articulation, which of the following is a specific advantage of a metal-on-metal bearing surface?

Figure 7 shows the AP radiograph of a 60-year-old man who has had pain in the thigh for past 6 months. History reveals that he underwent hip replacement 1 year ago. The radiographic changes are most likely the result of what process?

Figure 37 reveals a periprosthetic fracture around a cemented femoral stem in an 81-year-old patient with Paget's disease and mild coagulopathy. What is the most appropriate reconstructive management on the femoral side?