3. Adult Reconstruction (Hip & Knee) MCQs

A 60-year-old man presents with a painful right hip 6 years following a primary total hip arthroplasty. He has a metal-on-polyethylene bearing with a titanium femoral stem and a large diameter (36 mm) cobalt-chromium femoral head. Serum cobalt levels are markedly elevated at 12 ppb, while chromium levels are normal. An MRI reveals a solid tissue mass adjacent to the hip joint. What is the most likely etiology of this patient's presentation?

A 64-year-old man presents with progressive left groin pain 6 years after a primary total hip arthroplasty. The implant utilizes a titanium cementless stem, a cobalt-chromium femoral head, and a highly cross-linked polyethylene liner in a titanium shell. Radiographs show no evidence of component loosening. Laboratory workup reveals an erythrocyte sedimentation rate of 12 mm/hr, a C-reactive protein of 0.4 mg/L, a serum cobalt level of 16.5 mcg/L, and a serum chromium level of 1.2 mcg/L. An MRI demonstrates a solid-cystic pseudotumor in the joint space. What is the most likely etiology of his presentation?

A 68-year-old woman complains of recurrent knee swelling and a sensation of her knee 'giving way' particularly when descending stairs, 1 year after a primary posterior-stabilized total knee arthroplasty. On examination, the knee is completely stable to varus and valgus stress in full extension. At 90 degrees of flexion, there is 12 mm of joint opening with both varus and valgus stress, and a positive anterior drawer test. Which intraoperative technical error most likely caused this specific complication?

A 79-year-old woman sustains a fall and presents with severe thigh pain. She underwent a total hip arthroplasty 12 years ago with a polished taper-slip cemented stem. Radiographs demonstrate a periprosthetic spiral fracture of the femur located around the tip of the stem. The stem has subsided 3 cm compared to prior films, and the cement mantle is extensively fractured. Proximal bone stock is adequate.

According to the Vancouver classification, what is the most appropriate management?

A 62-year-old woman is 18 months post-op from a posterior-stabilized total knee arthroplasty. She reports a painful popping and catching sensation at the anterior aspect of her knee when extending her leg from a flexed seated position. Physical exam reveals a palpable, painful clunk at approximately 35-40 degrees of flexion as the knee extends. Which of the following implant design features or surgical factors is most strongly associated with this complication?

A 55-year-old active man complains of a high-pitched squeaking sound originating from his right hip when walking or bending, 3 years after receiving a primary total hip arthroplasty with a ceramic-on-ceramic bearing. He reports no pain, and radiographs show well-fixed components. Which of the following factors is most strongly associated with the development of this phenomenon?

A 72-year-old woman sustains a complete spontaneous rupture of her patellar tendon 4 years after a primary total knee arthroplasty. The implant components are clinically and radiographically well-fixed, and infection has been ruled out. She is scheduled for an extensor mechanism reconstruction using a whole extensor mechanism allograft. To optimize the functional outcome and minimize postoperative extensor lag, how should the allograft be tensioned during the reconstruction?

A surgeon is performing a crucial step in a posterior-stabilized total knee arthroplasty (TKA). After making the initial bone cuts, the trial components are placed. The knee is symmetric and balanced in extension but is too tight in flexion, preventing full range of motion. What is the most appropriate next step?

A 65-year-old woman undergoes primary total hip arthroplasty via a posterior approach. Six weeks postoperatively, she sustains a posterior dislocation while picking an item off the floor. CT scan demonstrates the acetabular component is placed in 45 degrees of inclination and 5 degrees of retroversion. The femoral stem is anteverted 15 degrees. What is the most appropriate definitive management if recurrent instability occurs?

A 72-year-old man presents with acute onset of severe right knee pain and swelling. He underwent primary TKA 5 years ago and had excellent function. Three days ago, he developed fever and chills following a routine dental cleaning without prophylactic antibiotics. Synovial fluid aspiration yields a WBC count of 85,000 cells/µL with 95% neutrophils. What is the most appropriate surgical management?

An 80-year-old man sustains a periprosthetic femur fracture around a cemented polished taper-slip femoral stem placed 10 years ago. Radiographs demonstrate a spiral fracture at the tip of the stem. The stem is radiographically loose with a fractured cement mantle, but there is adequate cortical bone stock both proximally and distally. According to the Vancouver classification, what is the most appropriate treatment?

A 58-year-old man presents with progressive groin pain 4 years after a primary metal-on-polyethylene THA utilizing a 36mm femoral head and a titanium alloy stem. Inflammatory markers are normal, and joint aspiration is negative for infection. Serum cobalt levels are markedly elevated (15 ppb) while chromium levels are mildly elevated (3 ppb). MARS MRI demonstrates a cystic mass communicating with the joint space. What is the most likely source of the elevated metal ions?

A 68-year-old woman complains of a painful 'catching' sensation in her knee when rising from a chair, 1 year after a posterior-stabilized TKA. Physical exam reveals a palpable pop at the superior pole of the patella as the knee actively extends from 40 degrees of flexion to full extension. What is the most likely pathogenesis of this condition?

A 62-year-old woman presents with acute onset of severe medial knee pain that began abruptly while walking. Radiographs show minimal joint space narrowing and no obvious fractures. MRI of the knee demonstrates localized bone marrow edema in the medial femoral condyle with a subchondral crescent sign, but no cortical collapse. What is the most appropriate initial management?

During preoperative templating for a total hip arthroplasty, a surgeon notes that the planned femoral component will increase the femoral neck offset by 8 mm compared to the contralateral native hip, without altering the leg length. Which of the following biomechanical effects will this change have?

A 70-year-old man complains of persistent anterior knee pain and a feeling of instability 2 years after a primary TKA. CT scan evaluation demonstrates that the femoral component is internally rotated 6 degrees relative to the surgical transepicondylar axis, and the tibial component is internally rotated 9 degrees relative to the medial third of the tibial tubercle. What is the most likely clinical consequence of this combined component positioning?

A 55-year-old active man underwent THA with a ceramic-on-ceramic bearing surface. Three years postoperatively, he complains of an audible squeaking sound from his hip during ambulation, though he denies any pain. Radiographs show well-fixed components with the acetabular cup placed in 65 degrees of inclination and 35 degrees of anteversion. What is the most likely underlying cause of the squeaking?

A 68-year-old woman who underwent a posterior-stabilized total knee arthroplasty 18 months ago presents with a painful catching sensation and an audible 'pop' when extending her knee from a flexed position. The range of motion is 0 to 120 degrees. Radiographs show well-fixed components with no evidence of loosening. Which of the following is the most likely cause of her symptoms?