3. Adult Reconstruction (Hip & Knee) MCQs

In the evaluation of a painful total knee arthroplasty for suspected periprosthetic joint infection (PJI), an alpha-defensin immunoassay of synovial fluid is obtained. Alpha-defensin is an antimicrobial peptide primarily secreted by which of the following cells in response to pathogens?

Following a primary total hip arthroplasty via a posterior approach, a patient experiences recurrent posterior dislocations. The acetabular component is found to be positioned in 45 degrees of abduction and 15 degrees of retroversion. What is the primary cause of instability?

According to the 2018 International Consensus Meeting (ICM) criteria, which of the following provides definitive evidence (Major Criteria) for the diagnosis of a periprosthetic joint infection (PJI)?

During a complex primary total knee arthroplasty (TKA), the surgeon inadvertently resects an excessive amount of the distal femur and compensates by using a thicker polyethylene insert, thereby elevating the joint line. What is the primary biomechanical consequence of elevating the joint line in TKA?

During a posterior-stabilized total knee arthroplasty, the trial components are placed. The surgeon notes that the knee is tight in flexion, causing lift-off, but symmetric and well-balanced in extension. Which of the following is the most appropriate next step to balance the knee?

In total hip arthroplasty, which of the following best describes the wear characteristics of ceramic-on-ceramic bearing surfaces compared to traditional metal-on-polyethylene bearings?

A 65-year-old woman complains of an audible 'clunk' and catching sensation when extending her knee from a flexed position, 18 months following a posterior-stabilized total knee arthroplasty. At what approximate degree of knee flexion does this phenomenon most commonly occur during active extension?

Ceramic-on-ceramic (CoC) bearing surfaces in total hip arthroplasty are known for extremely low wear rates. Which of the following lubrication regimes primarily governs the tribology of a well-functioning CoC articulation?

During a primary total knee arthroplasty, the surgeon checks the trial components. The knee demonstrates a symmetric and stable extension gap, but is excessively tight in flexion. Which of the following is the most appropriate step to balance the knee?

A 68-year-old female presents with progressive groin pain 10 years after a primary metal-on-polyethylene total hip arthroplasty. Radiographs reveal eccentric wear of the polyethylene liner and a large proximal femoral osteolytic lesion. What is the primary biologic mediator directly activated by wear debris to cause this osteolysis?

Highly cross-linked polyethylene (HXLPE) is commonly used in total hip arthroplasty to reduce volumetric wear. Which of the following is the most significant mechanical trade-off when increasing the cross-linking of polyethylene via high-dose irradiation?

A 68-year-old male presents with recurrent posterior dislocations following a primary total hip arthroplasty performed via a posterior approach 6 months ago. Plain radiographs and CT evaluation demonstrate a well-fixed, bone-ingrown acetabular component with 20 degrees of abduction and 5 degrees of retroversion. What is the most definitive and appropriate surgical intervention?

During a primary Total Knee Arthroplasty (TKA), the surgeon checks the trial components and finds that the knee has a stable, well-balanced extension gap, but the flexion gap is excessively tight. Assuming a standard anterior referencing system is used, which of the following maneuvers is the most appropriate next step to correct this specific mismatch?

In the selection of bearing surfaces for total hip arthroplasty (THA) in a young, active patient, which of the following combinations demonstrates the lowest volumetric wear rate but carries the highest risk of catastrophic failure secondary to component fracture?

A 55-year-old male who underwent a Metal-on-Metal total hip arthroplasty 8 years ago presents with increasing groin pain. Radiographs show no loosening. A MARS MRI reveals a large cystic mass communicating with the joint space. Aspiration yields sterile fluid. What characteristic histological finding is most likely present in the periprosthetic tissue?

A 70-year-old male with a painful total knee arthroplasty undergoes a synovial fluid aspiration. A synovial fluid alpha-defensin test returns positive. What is the cellular source and primary function of alpha-defensin in this context?

During a primary total knee arthroplasty in a patient with a severe, fixed valgus deformity, the knee remains tight laterally in both flexion and extension after standard bone cuts. Which of the following lateral structures should be sequentially released first to optimally balance the knee?

A 55-year-old female undergoes a primary total hip arthroplasty using a ceramic-on-ceramic bearing. At 2-year follow-up, she complains of an audible squeaking noise from the hip during specific movements. Which of the following acetabular component positions is most strongly associated with the development of this complication?

During a primary Total Knee Arthroplasty (TKA), the surgeon inserts trial components. Assessment of the gaps reveals that the knee is symmetrically excessively tight in both full extension and 90 degrees of flexion. Which of the following is the most appropriate next step to balance the knee?

A 48-year-old man who underwent a primary Total Hip Arthroplasty (THA) 3 years ago presents to the clinic complaining of an audible 'squeaking' sound coming from his hip during ambulation. He denies pain, and radiographs show well-fixed components. This complication is exclusively associated with which of the following bearing surface combinations?