This practice set contains high-yield board review questions covering key concepts in 3. Adult Reconstruction (Hip & Knee). Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 1441
Topic: 3. Adult Reconstruction (Hip & Knee)
What anatomic or mechanical feature primarily drives posterior femoral rollback during deep flexion in a cruciate-retaining (CR) total knee arthroplasty?
Correct Answer & Explanation
. Cam-post engagement
Explanation
In a CR total knee arthroplasty, the posterior cruciate ligament (PCL) is retained and its tension primarily drives femoral rollback. In a posterior-stabilized (PS) design, rollback is achieved mechanically via cam-post engagement.
Question 1442
Topic: Total Hip Arthroplasty (THA)
A 65-year-old female presents with recurrent anterior dislocations of her total hip arthroplasty. Intraoperative evaluation during revision reveals that the well-fixed acetabular component is in 35 degrees of anteversion, and the well-fixed femoral stem is in 20 degrees of anteversion. What is the most appropriate management?
Correct Answer & Explanation
. Revision of the femoral stem to a retroverted position
Explanation
Combined anteversion in THA should ideally be between 25 and 45 degrees. With a combined anteversion of 55 degrees, the patient is highly prone to anterior dislocation, and revising the cup to decrease anteversion addresses the source of instability.
Question 1443
Topic: 3. Adult Reconstruction (Hip & Knee)
A patient develops a diffuse, eczematous dermatitis over the surgical knee and progressive joint stiffness 6 months following a primary TKA. Infection is definitively ruled out. Patch testing confirms a severe nickel allergy. The pathogenesis of this reaction is best described as:
Correct Answer & Explanation
. IgE-mediated mast cell degranulation
Explanation
Metal hypersensitivity (such as nickel allergy) following arthroplasty represents a Type IV delayed hypersensitivity reaction. It is mediated by antigen-specific T-cells rather than antibodies.
Question 1444
Topic: 3. Adult Reconstruction (Hip & Knee)
Which of the following design factors has been most strongly associated with an increased risk of mechanically assisted crevice corrosion (trunnionosis) at the head-neck junction in total hip arthroplasty?
Correct Answer & Explanation
. Use of a 28 mm cobalt-chromium femoral head
Explanation
Large-diameter cobalt-chromium femoral heads increase the lever arm and torque forces at the modular head-neck junction (trunnion). This significantly increases the risk of fretting and crevice corrosion (trunnionosis).
Question 1445
Topic: 3. Adult Reconstruction (Hip & Knee)
Which of the following is classically considered an absolute contraindication to performing a medial unicompartmental knee arthroplasty (UKA)?
Correct Answer & Explanation
. Age greater than 70 years
Explanation
Inflammatory arthropathies (e.g., rheumatoid arthritis) involve the entire synovium and affect all joint compartments, making partial joint replacement inappropriate. UKA is contraindicated due to the high risk of rapid progression in the retained compartments.
Question 1446
Topic: Total Hip Arthroplasty (THA)
A patient complains that their operative leg feels longer after a primary THA. Clinical examination reveals the distance from the umbilicus to the medial malleolus is equal bilaterally, but the distance from the anterior superior iliac spine (ASIS) to the medial malleolus is 2 cm longer on the operative side. Which of the following best explains these findings?
Correct Answer & Explanation
. True leg length discrepancy
Explanation
Measurements from the ASIS to the medial malleolus evaluate true leg length, while measurements from the umbilicus to the medial malleolus evaluate apparent leg length. A longer ASIS-malleolus distance confirms a true leg length discrepancy, with pelvic tilt masking the apparent length.
Question 1447
Topic: 3. Adult Reconstruction (Hip & Knee)
Which of the following preoperative patient characteristics is statistically the most significant independent risk factor for deep wound infection and poor wound healing following total knee arthroplasty?
Correct Answer & Explanation
. Controlled essential hypertension
Explanation
Poorly controlled diabetes (HbA1c > 8.0%) dramatically increases the risk of periprosthetic joint infection and impaired wound healing. Strict preoperative glycemic control is universally recommended for risk mitigation.
Question 1448
Topic: 3. Adult Reconstruction (Hip & Knee)
What is the primary indication for performing a total wrist arthroplasty in a patient with painful rheumatoid arthritis?
Correct Answer & Explanation
. Contralateral wrist arthrodesis
Explanation
The most conservative indications for a total wrist arthroplasty are to spare motion on one side and to improve activities of daily living. Component loosening, dislocation, and wound problems are frequent. Suitable patients can be of various ages, wrist motion, and radiographic stages of arthritis. Ipsilateral total elbow arthroplasty, type III degenerative changes of the wrist, age older than 55, and limited range of motion are neither primary indications nor contraindications to a total wrist arthroplasty. None of the provided options are primary indications; however, based on the provided structure, the question implies identifying a valid clinical context, though the explanation notes these are not primary indications.
Question 1449
Topic: Total Hip Arthroplasty (THA)
A 65-year-old active woman undergoes elective total hip replacement in which a posterior approach is used. She has minimal pain and is discharged to home 2 days after surgery. Four weeks later, she dislocates her hip while shaving her legs. She undergoes a closed reduction in the emergency department. Postreduction radiographs show a reduced hip with well-fixed components in satisfactory alignment. What is the most appropriate management of this condition from this point forward?
Correct Answer & Explanation
. Observation and patient education regarding hip dislocation precautions
Explanation
First-time early dislocations are often treated successfully without revision surgery, especially when no component malalignment is present. In this clinical scenario, it appears the patient would benefit from better education about dislocation precautions. Hip orthoses are of questionable benefit unless the patient is cognitively impaired. Revision surgery can be successful but is usually reserved for patients with recurrent dislocations.
Question 1450
Topic: Total Hip Arthroplasty (THA)
A 70-year-old man undergoes removal of an infected total hip arthroplasty (THA) and insertion of an articulating antibiotic-loaded spacer to treat a deep periprosthetic hip infection. While in a nursing home receiving intravenous antibiotics 3 weeks after surgery, the patient trips and falls. Examination reveals swelling in the mid and distal thigh, intact skin and neurovascular structures, and severe pain with knee or hip movement. Radiographs of the femur are shown in Figures 1 through 4. What is the most appropriate treatment for the fracture below the implant?
Correct Answer & Explanation
. Open reduction and internal fixation of the fracture with a lateral plate and screws
Explanation
This patient has a type C periprosthetic femoral fracture. The articulating spacer is not involved in the fracture, which is well distal to the implant. The most appropriate treatment is open reduction and internal fixation of the fracture. Traction is not appropriate for this fracture because the injury can be treated surgically despite the history of previous hip infection.
Question 1451
Topic: 3. Adult Reconstruction (Hip & Knee)
What is the most likely late complication associated with cementless total knee replacement?
Correct Answer & Explanation
. Osteolysis
Explanation
In cementless total knee replacement, the risk of osteolysis is 30% if both components are placed without cement and screws are used for tibial fixation. The risk is 10% when a cemented tibial component is used, and the risk is 0% when both components are cemented.
Question 1452
Topic: 3. Adult Reconstruction (Hip & Knee)
In the preoperative planning of revision acetabular reconstruction, the surgeon should identify significant posterior column deficiency by noting which of the following radiographic features?
Correct Answer & Explanation
. Osteolysis in the ischium
Explanation
DISCUSSION: Proximal and medial migration of the femoral head usually indicates deficiencies of the dome or anterior column. Wear of the polyethylene may result in osteolysis and impingement, which are not indicative of any major bone deficiency. A significant osteolytic lesion in the ischium may represent a major posterior column deficiency that can create a technical challenge during the reconstruction.
Question 1453
Topic: 3. Adult Reconstruction (Hip & Knee)
A 68-year-old woman underwent an uncemented medial/lateral tapered femoral placement during a total hip arthroplasty. The orthopaedic surgeon noticed a nondisplaced vertical fracture in the calcar region of the femoral neck during final implant insertion. What is the most appropriate treatment?
Correct Answer & Explanation
. Removal of the implant, placement of a cerclage wire around the femoral neck above the lesser trochanter, and reinsertion of the implant
Explanation
DISCUSSION: The recognized treatment for a proximal periprosthetic fracture is to first identify the extent and then optimize the correction of the fracture. Several studies indicate that proximal cerclage wiring is adequate to create "barrel hoop" stability of the proximal femur. Braided cables offer superior stability compared with twisted wires or Luque wires. Finally, the appropriate postoperative treatment is protected weight bearing for 6 weeks, with periodic radiographs taken at 2-week intervals.
Question 1454
Topic: Total Knee Arthroplasty (TKA)
A 42-year-old manual laborer presents with isolated medial compartment knee pain. Standing alignment radiographs demonstrate 8 degrees of varus alignment. He has grade III medial compartment osteoarthritis and normal lateral and patellofemoral compartments. ROM is 5 to 120 degrees. He is a non-smoker. Which of the following is a relative contraindication to performing a medial opening wedge high tibial osteotomy (HTO) in this patient?
Correct Answer & Explanation
. Flexion contracture of 20 degrees
Explanation
High tibial osteotomy (HTO) is indicated for active patients with unicompartmental knee osteoarthritis and malalignment. Contraindications include inflammatory arthritis, patellofemoral arthritis, flexion contracture > 15 degrees, knee flexion < 90 degrees, bone loss/osteopenia, and smoking. A flexion contracture of 20 degrees is a relative/absolute contraindication as HTO does not correct sagittal plane contractures well.
Question 1455
Topic: 3. Adult Reconstruction (Hip & Knee)
A 45-year-old female presents with symptomatic, isolated lateral compartment knee osteoarthritis. Standing alignment radiographs demonstrate 8 degrees of valgus mechanical axis deviation. The deformity is localized to the distal femur. Which of the following is the most appropriate surgical intervention to unload the lateral compartment?
Correct Answer & Explanation
. Medial closing-wedge distal femoral osteotomy
Explanation
For a valgus knee deformity driving lateral compartment osteoarthritis, a distal femoral osteotomy (DFO) is indicated because the deformity typically arises from the femur. A medial closing-wedge DFO reliably corrects the mechanical axis towards the medial compartment, unloading the lateral joint.
Question 1456
Topic: 3. Adult Reconstruction (Hip & Knee)
A 68-year-old woman who underwent a right total hip arthroplasty 1 year ago has dislocated her hip five times since surgery. Radiographs show a retroverted acetabular component. What is the best treatment for this patient?
Correct Answer & Explanation
. Revise the acetabular component to 15 degrees of anteversion and 45 degrees of abduction
Explanation
The most common cause of recurrent dislocation following total hip arthroplasty continues to be component malposition. Component malposition should be addressed prior to any other treatment options, such as increasing soft-tissue tension with increased femoral offset or greater trochanteric advancement. A larger femoral head size may help, but correcting the component malposition should give more predictable results. A retroverted acetabular component should be revised to 15 degrees to 20 degrees of anteversion, matching the patient’s anatomy with an abduction angle close to 45 degrees.
Question 1457
Topic: 3. Adult Reconstruction (Hip & Knee)
Figures below show the clinical photograph and radiograph obtained from a 62-year-old man who has deformity and pain 1 year after primary total hip arthroplasty. What is the reason for the observed deformity?
Correct Answer & Explanation
. Loosening and subsidence of the femoral stem into retroversion
Explanation
Figure 1 reveals an external rotation deformity of the right lower extremity. This deformity can have numerous causes, including extra-articular deformity. Figure 2 reveals a loose, subsided femoral component. Femoral stems typically subside into retroversion due to proximal femoral biomechanics, which cause a compensatory external rotation deformity. The combined findings from both images suggest an external rotation deformity most likely related to subsidence into retroversion.
Question 1458
Topic: 3. Adult Reconstruction (Hip & Knee)
When compared with a conventional ultra-high molecular weight polyethylene (UHMWPE) bearing surface in total hip arthroplasty, a highly cross-linked polyethylene (XLPE) bearing surface is associated with
Correct Answer & Explanation
. significantly reduced wear and greater mid-term implant survival.
Explanation
XLPE was developed to address the problem of wear and osteolysis associated with conventional UHMWPE-bearing surfaces. Data have shown, with randomized controlled trials, that XLPE liners have significantly reduced wear and are associated with greater implant survival at 10 years compared with UHMWPE-bearing surfaces.
Question 1459
Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 2 shows the AP radiograph of an 18-year-old woman with progressive and severe right hip pain. Nonsteroidal anti-inflammatory drugs no longer control her pain. What is the next most appropriate step in management?
Correct Answer & Explanation
. Periacetabular osteotomy
Explanation
DISCUSSION: A concentric hip with acetabular dysplasia in a symptomatic patient is best treated by periacetabular osteotomy. The Salter osteotomy is less optimal because the method has limited correction, is uniaxial, cannot be tailored to the deformity, and lateralizes the entire hip joint, thereby increasing the joint reactive forces. Because the hyaline cartilage of the joint is histologically normal, rotating the hyaline cartilage into an optimal position is preferable to augmenting the acetabulum with a shelf or by Chiari osteotomy. Varus intertrochanteric osteotomy has no significant role in the treatment of acetabular dysplasia. Total hip arthroplasty may be required in the future but should not be the first choice. REFERENCE: Millis MB, Murphy SB, Poss R: Osteotomies about the hip for the prevention and treatment of osteoarthritis. Instr Course Lect 1996;45:209-226.
Question 1460
Topic: 3. Adult Reconstruction (Hip & Knee)
A 72-year-old man undergoes an uncomplicated cementless total hip arthroplasty for advanced osteoarthritis. At his 6-week postoperative follow-up, he has minimal pain and is progressing well with his mobility. Radiographs show early formation of Brooker grade III heterotopic bone around his hip. What is the best treatment of the heterotopic bone at this time?
Correct Answer & Explanation
. Observation, repeat radiographs, and reexamination in 6 weeks
Explanation
DISCUSSION: The development of heterotopic bone occurs early after hip arthroplasty. Prophylactic treatment must be in the early postoperative period. At 6 weeks, prophylactic treatment with NSAIDs or radiation is no longer effective. Surgery at 10 weeks would be premature because the patient is currently asymptomatic with regards to the heterotopic bone, and surgery prior to full maturation of the bone may increase the risk for more abundant recurrence of bone.
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