3. Adult Reconstruction (Hip & Knee) MCQs

A surgeon is performing a cruciate-retaining (CR) total knee arthroplasty. Upon trialing the components, the surgeon notes that the anterior aspect of the tibial tray lifts off the baseplate during deep flexion. What is the most likely cause of this phenomenon?

A 62-year-old male is being evaluated for a unicompartmental knee arthroplasty (UKA) for isolated medial compartment osteoarthritis. According to the classic Kozinn and Scott criteria, which of the following is an absolute contraindication for a medial UKA?

A 70-year-old male returns to the clinic 14 days after a primary total knee arthroplasty with an acutely swollen, red, and painful knee. He has had fevers for 24 hours. Aspiration confirms acute periprosthetic joint infection with a well-fixed implant. Which treatment has the highest likelihood of success for retaining his current implant?

The use of a larger femoral head in total hip arthroplasty reduces the risk of dislocation primarily through which biomechanical mechanism?

During a total knee arthroplasty for a fixed valgus deformity, the surgeon notes that the lateral gap is critically tight in flexion but balanced in extension. Which structure should be preferentially released to correct this specific gap mismatch?

While performing an anterolateral approach to the hip, the surgeon proceeds to release the reflected head of the rectus femoris to improve acetabular exposure. Ligation of which of the following vascular structures is necessary to prevent significant hemorrhage during this step?

A 75-year-old female presents for revision total hip arthroplasty. Pelvic radiographs demonstrate severe acetabular bone loss. The teardrop is obliterated, Kohler's line is discontinuous (broken), and the hip center has migrated 4 cm superiorly and 2 cm medially. What is the correct Paprosky classification for this defect?

In the manufacturing of highly cross-linked polyethylene (HXLPE) for total hip arthroplasty, increasing the radiation dose to promote cross-linking results in which of the following mechanical changes compared to conventional ultra-high-molecular-weight polyethylene?

A novel diagnostic laboratory test for periprosthetic joint infection (PJI) is evaluated in a multicenter study. If the prevalence of PJI in the tested population is artificially increased from 5% to 20% due to selection bias, how will the test's positive predictive value (PPV) and negative predictive value (NPV) change, assuming sensitivity and specificity remain constant?

Zirconia ceramics were historically developed to address the inherent brittleness and fracture risk of alumina in total joint arthroplasty. The advanced mechanism of "phase transformation toughening" in partially stabilized zirconia refers to a structural lattice shift at the tip of a propagating micro-crack. This toughening shift occurs between which two distinct crystalline phases?

What type of wear is characterized by the transfer of material from a softer bearing surface (e.g., polyethylene) to a harder bearing surface (e.g., metal), leading to localized bonding and subsequent tearing of the softer material?

In normal articular cartilage, the primary mechanism of lubrication during high-load, rapid motion (such as the heel strike phase of gait) is best described by which of the following models?

In the pathogenesis of aseptic loosening following total joint arthroplasty, the biological response is triggered by particulate wear debris. Which of the following cell types is the primary initiator of the osteolytic cascade by phagocytosing particles and subsequently releasing TNF-alpha, IL-1, and IL-6?

Highly cross-linked polyethylene (HXLPE) is utilized in total hip arthroplasty to minimize wear. High-dose irradiation generates free radicals that can cause oxidative degradation over time. How are these free radicals typically eliminated during manufacturing?

An MRI of the hip reveals an intra-articular mass requiring a surgical dislocation via a posterior approach. To protect the deep branch of the medial circumflex femoral artery (MCFA), the tendon of which muscle must be preserved or carefully handled?

An 80-year-old female presents with a periprosthetic femur fracture around her cemented total hip arthroplasty. Radiographs reveal a fracture extending around the tip of the stem. The stem is loose, but there is good remaining proximal and distal bone stock. What is the Vancouver classification, and what is the standard treatment?

An 80-year-old female presents with a periprosthetic femur fracture around a cemented total hip arthroplasty. Radiographs show a fracture at the tip of the stem. The stem is radiographically loose with subsidence, and the proximal femoral bone stock is extremely poor and fragmented. What is the Vancouver classification and the most appropriate treatment?

An 80-year-old female with a prior cemented total hip arthroplasty falls and sustains a periprosthetic femur fracture. Radiographs show a fracture around the tip of the stem. The stem appears radiographically loose, but there is adequate surrounding bone stock. According to the Vancouver classification, how is this classified and primarily treated?