3. Adult Reconstruction (Hip & Knee) MCQs

Six weeks after a primary posterior-approach total hip arthroplasty, a 65-year-old female presents to the emergency department with a posterior dislocation that occurred while rising from a low toilet. Which of the following component malpositions is the most likely primary contributor to her instability?

A 60-year-old male with a metal-on-metal total hip arthroplasty performed 8 years ago presents with worsening groin pain and a palpable mass. Radiographs show well-fixed implants with no osteolysis. Joint aspiration yields fluid with a normal leukocyte count and negative cultures. MRI reveals a large, solid-cystic pseudotumor. Which of the following is the most likely diagnosis?

In Total Hip Arthroplasty, what type of wear is predominantly responsible for the generation of submicron particles that lead to macrophage-induced osteolysis?

According to the 2018 Musculoskeletal Infection Society (MSIS) criteria, which of the following is considered a major criterion for the diagnosis of a periprosthetic joint infection, diagnosing it definitively without the need for additional scoring?

During a primary posterior-stabilized total knee arthroplasty, the surgeon evaluates gap kinematics and notes the knee is tight in extension but well-balanced in flexion. Which of the following intra-operative maneuvers is most appropriate to correctly balance the knee?

In total hip arthroplasty, acetabular component malposition is a major risk factor for dislocation. Which of the following values represents the 'safe zone' for acetabular cup placement as described by Lewinnek?

In a cruciate-retaining total knee arthroplasty, the surgeon notes that the knee is perfectly balanced in extension but significantly tight in flexion. What is the most appropriate next step?

A 68-year-old female undergoes a posterior approach total hip arthroplasty. During trialing, the hip dislocates posteriorly when positioned in flexion, adduction, and internal rotation. What is the most appropriate intraoperative adjustment?

In the biomechanics of metal-on-polyethylene total hip arthroplasty, which of the following wear mechanisms is primarily responsible for the generation of submicron polyethylene debris that ultimately leads to macrophage activation and periprosthetic osteolysis?

In a posterior-stabilized (PS) total knee arthroplasty, the posterior cruciate ligament (PCL) is resected. What is the primary biomechanical function of the implanted cam-and-post mechanism during knee flexion?

A 55-year-old male who underwent a ceramic-on-ceramic total hip arthroplasty three years ago presents complaining of a reproducible squeaking noise from his hip during specific movements. What is the most frequently cited biomechanical cause for this auditory phenomenon?

A patient experiences recurrent posterior dislocations following a primary Total Hip Arthroplasty (THA). CT scan evaluation reveals the acetabular cup is placed in 10 degrees of anteversion and 40 degrees of abduction. The femoral stem is in 5 degrees of anteversion. What is the most likely cause of the instability?

During a Total Knee Arthroplasty (TKA), trial components are inserted. The surgeon notes that the extension gap is excessively tight, but the flexion gap is perfectly balanced and stable. Which of the following is the most appropriate next step to correct the gap kinematics?

Following a displaced intracapsular femoral neck fracture, avascular necrosis of the femoral head is a significant risk. Which vessel provides the primary blood supply to the weight-bearing dome of the adult femoral head?

In total hip arthroplasty, increasing the femoral head size directly impacts hip stability. What biomechanical parameter is most significantly increased by utilizing a larger femoral head?

A 68-year-old male undergoes revision total knee arthroplasty due to persistent pain and swelling 18 months post-primary surgery. Preoperative workup showed elevated ESR and CRP, and aspiration yielded cloudy fluid. Intraoperatively, there is evidence of synovitis. Periprosthetic tissue cultures initially return negative after 5 days. What is the most appropriate next step in confirming a periprosthetic joint infection (PJI) diagnosis given these findings?

A 72-year-old female presents with recurrent posterior dislocations following a total hip arthroplasty done 6 months ago. Radiographs show the acetabular component is in 30 degrees of inclination and 0 degrees of anteversion. What is the most appropriate surgical management?

A 75-year-old female, who plays tennis three times a week and is medically fit, sustains a displaced intracapsular femoral neck fracture (Garden IV). What is the most appropriate surgical treatment to minimize reoperation and maximize functional outcome?

A 68-year-old male presents with recurrent posterior dislocations following a primary total hip arthroplasty performed via a posterior approach. Radiographic evaluation of the acetabular component demonstrates an anteversion of 5 degrees and an inclination of 35 degrees. What is the most likely cause of his instability?