3. Adult Reconstruction (Hip & Knee) MCQs

During a primary total knee arthroplasty, after making the standard initial bone cuts, trial components are placed. The knee is found to be tight in flexion but well-balanced in extension. Which of the following surgical adjustments is most appropriate to balance the gaps?

A 60-year-old female suffers recurrent posterior dislocations following a primary total hip arthroplasty performed via a posterior approach. Radiographs demonstrate the acetabular cup is positioned in 45 degrees of inclination and 0 degrees of anteversion. What is the primary mechanical cause of her instability?

A 65-year-old man presents with knee pain 2 years after a total knee arthroplasty. Synovial fluid aspiration yields a white blood cell count of 3,500 cells/µL with 75% neutrophils. Which of the following is considered a major criterion for definitive periprosthetic joint infection (PJI) according to the 2018 International Consensus Meeting (ICM) criteria?

A 55-year-old female undergoes a total hip arthroplasty utilizing a ceramic-on-ceramic bearing. One year postoperatively, she complains of a high-pitched squeaking noise during gait. Which component factor is most strongly associated with the development of this phenomenon?

Which wear mechanism is primarily responsible for the generation of submicron polyethylene wear debris, which ultimately triggers macrophage-mediated osteolysis in total hip arthroplasty?

A 68-year-old female sustains a posterior dislocation of her total hip arthroplasty 4 weeks postoperatively. The index procedure was performed via a posterior approach. She is successfully closed reduced in the emergency department. What is the most common etiology for early posterior instability in this specific clinical setting?

A 62-year-old man presents with progressive groin pain 5 years after receiving a modern metal-on-polyethylene total hip arthroplasty. Serum cobalt and chromium levels are significantly elevated, and an MRI with MARS sequencing reveals a large fluid collection around the hip joint. What is the most likely source of the elevated metal ions?

Following a total hip arthroplasty via a posterior approach, a patient experiences recurrent posterior dislocations. Radiographs reveal the acetabular component is placed in 30 degrees of abduction and 5 degrees of retroversion. What is the most appropriate definitive management?

A 68-year-old male presents with a painful total knee arthroplasty 3 years post-operatively. Synovial fluid analysis reveals a WBC count of 4,500 cells/mcL with 85% PMNs. Alpha-defensin is positive. No sinus tract is present. According to the MSIS criteria, what is the diagnostic conclusion?

A 45-year-old female undergoes a metal-on-metal hip resurfacing arthroplasty. Two years later, she develops groin pain. Workup reveals an elevated serum cobalt-to-chromium ratio and a solid, cystic mass communicating with the joint. What is the most critical biomechanical risk factor for developing this adverse local tissue reaction (ALTR)?

Which of the following is considered an absolute contraindication to medial unicompartmental knee arthroplasty (UKA) for isolated medial compartment osteoarthritis?

A 62-year-old female complains of a painful catch and an audible pop when extending her knee from a flexed position, one year after a posterior-stabilized total knee arthroplasty. What is the most likely pathophysiologic cause of this specific complication?

An 80-year-old female with a cemented total hip arthroplasty sustains a fall. Radiographs show a periprosthetic femur fracture around the tip of the stem. The stem remains well-fixed within the cement mantle. What is the Vancouver classification and appropriate treatment?

A 45-year-old male presents with a transverse acetabular fracture following a fall. A CT scan confirms a transverse pattern involving both columns. The hip is concentrically reduced, and there is no significant displacement or intra-articular incongruity.

Which of the following is the most appropriate management strategy?

A 65-year-old female sustains a 4-part proximal humerus fracture. Which of the following anatomical factors is the most critical predictor of avascular necrosis of the humeral head in this setting?

Which of the following anatomic variants is a well-documented intrinsic anatomic risk factor for a non-contact anterior cruciate ligament (ACL) tear?

A 45-year-old highly active male undergoes a primary total hip arthroplasty with a ceramic-on-ceramic bearing surface. One year postoperatively, he complains of a loud, audible squeaking sound from the hip during deep flexion. Which component position is most highly associated with this phenomenon?

Aseptic loosening is the most common cause of failure in total joint arthroplasty and is driven by the biologic response to particulate wear debris. Which cell type is primarily responsible for phagocytosing these particles and subsequently releasing osteolytic cytokines like TNF-alpha and IL-1?

During a primary total knee arthroplasty, a surgeon utilizes spacer blocks to evaluate the ligamentous gaps before making the final bony cuts. The knee is perfectly balanced and stable in 90 degrees of flexion, but it is too tight in full extension. Which of the following surgical steps is most appropriate to balance the gaps?