3. Adult Reconstruction (Hip & Knee) MCQs

A 78-year-old female falls and sustains a spiral fracture around the stem of her cementless total hip arthroplasty. Radiographs show the fracture propagates 3 cm distal to the lesser trochanter. Comparing current films to preoperative films, the stem has subsided by 1.5 cm. According to the Vancouver classification, what is the recommended treatment?

A 70-year-old patient with a painful, swollen TKA has an alpha-defensin test that is positive, and synovial fluid shows 15,000 WBC/µL with 90% neutrophils. The patient has been off antibiotics for 4 weeks, yet routine aerobic, anaerobic, and fungal cultures remain negative after 14 days of incubation. What is the most sensitive next diagnostic step to identify the causative organism?

A 55-year-old active male underwent a primary total hip arthroplasty with a ceramic-on-ceramic articulation 3 years ago. He now complains of a loud, audible squeaking sound from his hip during gait, though he denies pain. Radiographs demonstrate a well-fixed femoral stem and an acetabular cup positioned in 65 degrees of inclination. What is the primary mechanical cause of the squeaking?

A 68-year-old patient on chronic immunosuppressive therapy develops a periprosthetic joint infection of their TKA. Synovial fluid cultures definitively grow Candida albicans. According to current consensus guidelines, what is the most appropriate management strategy for this fungal PJI?

A patient complains of a significant leg length discrepancy (LLD), feeling that the operative leg is too long, 6 weeks after a primary total hip arthroplasty. On the AP pelvis radiograph, the distance from the lesser trochanter to the center of the femoral head is 15 mm greater on the operative side compared to the normal side, while the acetabular teardrop to head center distances are equal. What surgical error most likely occurred?

A 68-year-old male presents with chronic pain two years after a primary total knee arthroplasty. Synovial fluid aspiration yields a white blood cell count of 4,200 cells/uL with 85% polymorphonuclear cells. However, aerobic and anaerobic cultures show no growth at 7 days. Which of the following synovial fluid biomarkers has the highest specificity for confirming a diagnosis of periprosthetic joint infection (PJI) in this culture-negative scenario?

A 55-year-old female with a ceramic-on-ceramic total hip arthroplasty presents with a loud squeaking noise from her hip during walking. She is otherwise pain-free and radiographs show no radiolucencies. Which of the following factors regarding component positioning is most strongly associated with this phenomenon?

A 70-year-old male with a well-functioning total knee arthroplasty for 5 years presents with 3 days of acute, severe knee pain, swelling, and erythema following a dental extraction. Aspiration yields frankly purulent fluid with a WBC count of 85,000 cells/uL. What is the most appropriate surgical management?

A 62-year-old patient undergoes a primary total hip arthroplasty utilizing the direct anterior approach. Postoperatively, the patient complains of a burning, numbing sensation over the anterolateral aspect of the operated thigh. Which of the following nerves was most likely injured or stretched during the surgical exposure?

When planning a two-stage revision for a chronic periprosthetic joint infection of the knee, an orthopedic surgeon must decide between an articulating and a static cement spacer. Which of the following is a primary indication for utilizing a static spacer over an articulating one?

A 72-year-old female presents with her third posterior dislocation of her total hip arthroplasty. A review of her postoperative CT scan evaluating component position is ordered. Which of the following cup positions is the most likely culprit for recurrent posterior instability?

A patient with a painful total knee arthroplasty is suspected of having a chronic periprosthetic joint infection and is currently taking oral antibiotics prescribed by their primary care physician. To maximize the diagnostic yield of a synovial fluid aspiration for culture, how long should the antibiotics ideally be withheld before performing the arthrocentesis?

A 60-year-old male with a metal-on-polyethylene total hip arthroplasty utilizing a standard titanium stem and a large-diameter cobalt-chromium femoral head presents with groin pain and an associated soft-tissue pseudotumor 6 years postoperatively. Which of the following serum laboratory profiles is most characteristic of mechanically assisted crevice corrosion (MACC) at the head-neck junction?

In a two-stage exchange arthroplasty for a periprosthetic knee infection, articulating spacers are frequently utilized. Compared to static spacers, which of the following is the primary advantage of utilizing an articulating spacer?

A 55-year-old male presents with new-onset groin pain 12 years after a primary total hip arthroplasty. Radiographs reveal eccentric polyethylene wear and a 3 cm retroacetabular osteolytic lesion. The acetabular shell is well-fixed and correctly positioned. What is the most appropriate surgical management?

A 70-year-old female undergoes a revision total hip arthroplasty via a posterior approach. Intraoperatively, the well-fixed acetabular component is noted to be retroverted by 10 degrees, but removal would result in massive bone loss. If the cup is retained, which adjustment to the modular femoral stem would best compensate for this acetabular malposition to prevent posterior instability?

According to the current literature, what is the optimal timeframe to perform a Debridement, Antibiotics, and Implant Retention (DAIR) procedure for an acute hematogenous periprosthetic knee infection to maximize the probability of infection eradication?

A 65-year-old male with a metal-on-polyethylene total hip arthroplasty presents with unexplained groin pain 5 years postoperatively. Radiographs show well-fixed components without osteolysis. Laboratory analysis reveals significantly elevated serum cobalt levels with normal serum chromium. What is the most likely etiology of his symptoms?

The introduction of highly cross-linked polyethylene (HXLPE) has significantly reduced wear rates and subsequent osteolysis in total hip arthroplasty. However, the irradiation process used to create HXLPE alters its mechanical properties. Which of the following is a primary mechanical disadvantage of this process?

A patient undergoes total hip arthroplasty. The choice of bearing surface is critical. Which material pairing typically exhibits the lowest wear rate in modern hip arthroplasty?