3. Adult Reconstruction (Hip & Knee) MCQs

A 68-year-old woman with a 9-year history of type II diabetes is seen 11 weeks after an uncemented left total hip replacement. When seen 6 weeks after surgery, some mild erythema and induration at the distal incision was noted, but no drainage. She states that drainage started 2 weeks ago. Examination shows turbid drainage coming from the distal third of the incision with mild surrounding erythema. Hip range of motion causes mild discomfort. Investigations reveal an erythrocyte sedimentation rate of 45 mm/h(reference range, 0-20 mm/h) and C-reactive protein of 54 mg/L (reference range, 0.08-3.1 mg/L). A rapid polymerase chain reaction of the swabbed fluid is positive for methicillin-resistant Staphylococcus aureus.Hip aspiration under fluoroscopy is attempted but no fluid is obtained. What is the most appropriate treatment?

An 82-year-old female with a history of a cemented right total hip arthroplasty performed 12 years ago presents after a ground-level fall. Radiographs demonstrate a fracture around the tip of the femoral stem. The stem is radiographically loose, but there is adequate remaining femoral bone stock. According to the Vancouver classification, how should this fracture be managed?

A 35-year-old man presents with a posterior hip dislocation and associated posterior wall acetabular fracture after a motor vehicle collision. Closed reduction is performed in the emergency department. The post-reduction CT scan reveals a 40% posterior wall defect with a significant area of marginal impaction. What is the most critical step during open reduction and internal fixation to ensure a congruent joint and minimize post-traumatic arthritis?

In aseptic loosening of a total hip arthroplasty, osteolysis is primarily driven by the biological response to particulate wear debris. Which of the following cell types is the primary effector that phagocytoses the polyethylene debris and initiates the inflammatory cascade?

In total joint arthroplasty, particulate debris can lead to osteolysis and implant loosening. Wear that occurs between two primary bearing surfaces intended for motion (e.g., the femoral head and the polyethylene liner) is classified as which of the following?

During pre-operative templating for a primary total hip arthroplasty (THA), the surgeon decides to use a high-offset femoral stem instead of a standard-offset stem of the same neck length. What is the primary biomechanical effect of this decision?

During a revision total knee arthroplasty (TKA), the surgeon uses a smaller femoral component and makes up the flexion space by using a thicker polyethylene insert. What is the most likely geometric consequence of this technical decision?

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

A 68-year-old male presents with deep thigh pain 12 years after a cementless total hip arthroplasty. Radiographs demonstrate eccentric positioning of the femoral head within the acetabular cup and extensive periprosthetic radiolucencies.

What is the primary cellular mediator of the osteolysis demonstrated in this condition?

A patient complains of a painful catching sensation in their knee one year after undergoing a posterior-stabilized (PS) total knee arthroplasty. The physical examination reveals an audible pop as the knee is actively extended. At what arc of motion does 'patellar clunk syndrome' most classically occur?

Trunnionosis, or wear at the head-neck junction of a modular femoral stem, has become increasingly recognized in total hip arthroplasty. Which of the following implant combinations represents the highest risk factor for developing symptomatic trunnionosis?

A 72-year-old female sustains a fall and presents with a periprosthetic femur fracture around a cemented total hip arthroplasty placed 10 years ago. Radiographs show a fracture at the tip of the stem. The stem appears to have subsided 1 cm, and there is an intact medial calcar with good diaphyseal bone stock. Based on the Vancouver classification, what is the most appropriate definitive management?

During a primary total knee arthroplasty, the surgeon inadvertently places the femoral component in 5 degrees of internal rotation relative to the surgical transepicondylar axis. What is the expected clinical and biomechanical consequence of this malrotation?

Highly cross-linked polyethylene (XLPE) has dramatically reduced the incidence of wear and osteolysis in modern total hip arthroplasty. Which step in the manufacturing process of XLPE is essential for eliminating the free radicals created during the cross-linking phase, thereby improving oxidative stability?

A 78-year-old female presents for revision total knee arthroplasty due to aseptic loosening. Intraoperatively, following removal of the components and minimal debridement, the surgeon notes complete incompetence of both the Medial Collateral Ligament (MCL) and the Lateral Collateral Ligament (LCL), accompanied by a massive flexion gap. What is the most appropriate level of constraint for the new implant?

During a primary posterior-stabilized total knee arthroplasty, trial reduction reveals that the knee is perfectly balanced and symmetric in full extension, but the joint is significantly tight symmetrically in 90 degrees of flexion. Which of the following surgical steps is the most appropriate initial maneuver to balance this knee?