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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 228 of 326

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 4541

Topic: 3. Adult Reconstruction (Hip & Knee)
A patient presents with a posterior hip dislocation and an associated fracture of the femoral head that extends cephalad to the fovea capitis. According to the Pipkin classification, what type of fracture is this, and what is the primary indication for surgical fixation?
. Pipkin I; usually managed non-operatively
. Pipkin II; fixation is indicated if the fragment involves the weight-bearing surface and is displaced
. Pipkin III; immediate hemiarthroplasty is always required
. Pipkin IV; requires a combined anterior and posterior approach
. Pipkin II; routinely excised to prevent avascular necrosis

Correct Answer & Explanation

. Pipkin II; fixation is indicated if the fragment involves the weight-bearing surface and is displaced

Explanation

A Pipkin II fracture involves the femoral head superior to the fovea capitis, which includes the primary weight-bearing surface. Open reduction and internal fixation is indicated if the fragment is displaced to restore joint congruity and prevent post-traumatic arthritis.

Question 4542

Topic: Total Hip Arthroplasty (THA)

The main blood supply to the adult femoral head is derived from the deep branch of the medial femoral circumflex artery (MFCA). At what key anatomical location does the MFCA cross the obturator externus muscle?

. Anterior to the obturator externus tendon
. Posterior to the obturator externus tendon
. Superior to the piriformis tendon
. Inferior to the quadratus femoris
. Piercing the iliopsoas tendon

Correct Answer & Explanation

. Posterior to the obturator externus tendon

Explanation

The deep branch of the MFCA travels anterior to the superior gemellus and obturator internus but constantly crosses posterior to the obturator externus tendon. This relationship makes the vessel vulnerable during posterior approaches if the obturator externus is violated.

Question 4543

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old female undergoes a total hip arthroplasty for osteoarthritis. Postoperatively, she develops sudden severe groin pain and a leg length discrepancy with internal rotation and adduction. What is the most appropriate immediate management step?

. Revision total hip arthroplasty
. Closed reduction under anesthesia
. Open reduction and internal fixation
. Abduction brace application
. Observation and physical therapy

Correct Answer & Explanation

. Closed reduction under anesthesia

Explanation

The symptoms (sudden severe groin pain, leg length discrepancy, internal rotation, adduction) are classic for a posterior hip dislocation following total hip arthroplasty. The most appropriate initial management is emergent closed reduction under anesthesia, followed by assessment for stability and identification of predisposing factors. Revision surgery is reserved for recurrent instability or irreducible dislocations. An abduction brace might be used post-reduction, but not as the initial management.

Question 4544

Topic: Total Hip Arthroplasty (THA)

Which surgical approach to the hip is associated with the highest risk of postoperative dislocation, particularly posterior dislocation?

. Direct anterior approach
. Anterolateral approach
. Direct lateral approach
. Posterior approach
. Trochanteric osteotomy approach

Correct Answer & Explanation

. Posterior approach

Explanation

The posterior approach (Moore approach) to total hip arthroplasty is classically associated with a higher risk of posterior dislocation compared to anterior or lateral approaches, primarily due to posterior capsule and short external rotator muscle division. While modern techniques for posterior approach often involve repair of these structures, it historically carries the highest risk. The direct anterior approach and direct lateral approaches generally have lower dislocation rates, particularly for posterior dislocation.

Question 4545

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old male with severe osteoarthritis of the knee is undergoing total knee arthroplasty. During exposure, the surgeon notes a tight lateral compartment, making balanced soft tissue release necessary. Which structure should be considered for release to address lateral tightness in flexion?

. Pes anserinus
. Superficial medial collateral ligament
. Popliteus tendon
. Posterior oblique ligament
. Deep medial collateral ligament

Correct Answer & Explanation

. Popliteus tendon

Explanation

During total knee arthroplasty, a tight lateral compartment in flexion often requires release of the popliteus tendon. The popliteus muscle and its tendon are dynamic stabilizers of the posterolateral corner and restrict external rotation and posterior translation of the tibia. Releasing the popliteus tendon can help balance the lateral compartment in flexion. The pes anserinus and MCL are medial structures. The posterior oblique ligament is part of the deep MCL, also a medial structure.

Question 4546

Topic: 3. Adult Reconstruction (Hip & Knee)

What is the most reliable imaging modality for early detection of avascular necrosis of the femoral head?

. Plain radiographs
. CT scan
. Bone scan (Technetium-99m)
. MRI
. Ultrasound

Correct Answer & Explanation

. MRI

Explanation

Magnetic Resonance Imaging (MRI) is the most sensitive and specific imaging modality for the early detection of avascular necrosis (AVN) of the femoral head. It can detect changes in bone marrow signal before they are visible on plain radiographs or CT scans. Plain radiographs are often normal in early AVN. CT scans are good for assessing bone architecture but less sensitive than MRI for early marrow changes. Bone scans can show increased uptake but are less specific. Ultrasound has limited utility for this condition.

Question 4547

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old patient who underwent total knee arthroplasty six months ago presents with worsening knee pain, swelling, and a low-grade fever. ESR is 70 mm/hr and CRP is 85 mg/L. Joint aspiration reveals a cloudy fluid. Which of the following findings from the aspirate is MOST indicative of periprosthetic joint infection (PJI)?

. White blood cell (WBC) count of 1500 cells/µL
. Neutrophil percentage of 60%
. Glucose level significantly lower than serum glucose
. Positive leukocyte esterase test
. Aspiration fluid WBC count > 3000 cells/µL with >80% neutrophils

Correct Answer & Explanation

. Aspiration fluid WBC count > 3000 cells/µL with >80% neutrophils

Explanation

According to the Musculoskeletal Infection Society (MSIS) criteria for defining PJI, a synovial fluid WBC count greater than 3000 cells/µL with a neutrophil percentage greater than 80% is a major criterion for diagnosis, particularly for acute PJI. While other options can be supportive, this specific combination is highly indicative and a strong diagnostic marker for PJI, especially in conjunction with elevated ESR/CRP and clinical symptoms. A WBC count of 1500 with 60% neutrophils is less specific and might be seen in aseptic inflammation.

Question 4548

Topic: 3. Adult Reconstruction (Hip & Knee)
A 60-year-old patient who underwent total knee arthroplasty (TKA) 5 years ago presents with insidious onset of anterior knee pain and mild swelling. Radiographs show a thin radiolucent line (<1mm) at the bone-cement interface around the tibial component. What is the most likely cause of her symptoms?
. Infection
. Extensor mechanism dysfunction
. Patellofemoral pain
. Aseptic loosening
. Component malalignment

Correct Answer & Explanation

. Aseptic loosening

Explanation

Insidious onset of pain and a thin radiolucent line (<1mm) at the bone-cement interface around a TKA component, without other signs of infection, is highly suggestive of early aseptic loosening. This is a common mode of failure for cemented components. While infection needs to be ruled out, the absence of overt systemic signs and the specific radiographic finding point to aseptic loosening. Patellofemoral pain often presents differently, and extensor mechanism dysfunction might not show a radiolucent line.

Question 4549

Topic: 3. Adult Reconstruction (Hip & Knee)

A 75-year-old female with a previous right total hip arthroplasty falls and sustains a Vancouver Type B2 periprosthetic femoral fracture. Which of the following describes the fracture pattern and typical management?

. Fracture at the tip of the stem, stable implant; open reduction and plate fixation
. Fracture below the stem, stable implant; open reduction and plate fixation
. Fracture around the stem, loose implant; revision arthroplasty with a longer stem
. Fracture around the stem, stable implant; open reduction and plate fixation
. Fracture of the greater trochanter; usually conservative management

Correct Answer & Explanation

. Fracture around the stem, loose implant; revision arthroplasty with a longer stem

Explanation

A Vancouver Type B2 periprosthetic femoral fracture is characterized by a fracture around the femoral stem with evidence of a loose or unstable femoral component. The typical management involves revision total hip arthroplasty with a longer, often distally fixed, femoral stem to bypass the fracture and achieve stable fixation. Type B1 is around a stable stem, managed with ORIF. Type B3 involves significant bone loss and a loose stem, often requiring extensive reconstruction.

Question 4550

Topic: 3. Adult Reconstruction (Hip & Knee)

What is the MOST effective single prophylactic measure to reduce the risk of periprosthetic joint infection (PJI) in total joint arthroplasty?

. Laminar flow operating room ventilation
. Preoperative chlorhexidine shower
. Intravenous prophylactic antibiotics administered within 60 minutes of incision
. Using antibiotic-loaded bone cement
. Maintaining normothermia during surgery

Correct Answer & Explanation

. Intravenous prophylactic antibiotics administered within 60 minutes of incision

Explanation

Intravenous prophylactic antibiotics administered within 60 minutes prior to surgical incision are consistently shown to be the single most effective measure in reducing the risk of periprosthetic joint infection (PJI). While all listed options contribute to infection prevention, the timing and administration of antibiotics are paramount. Laminar flow, chlorhexidine showers, antibiotic cement, and normothermia are all important adjunctive measures but less impactful than appropriate antibiotic prophylaxis.

Question 4551

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old female sustains a displaced femoral neck fracture. She is otherwise healthy and active. What is the MOST appropriate definitive surgical treatment?

. Closed reduction and percutaneous pinning
. Dynamic hip screw fixation
. Hemiarthroplasty
. Total hip arthroplasty
. Non-operative management with traction

Correct Answer & Explanation

. Total hip arthroplasty

Explanation

For an active, otherwise healthy elderly patient (typically >60-65 years old) with a displaced femoral neck fracture, Total Hip Arthroplasty (THA) is generally considered the preferred treatment option over hemiarthroplasty. THA offers better functional outcomes and a lower re-operation rate for acetabular erosion compared to hemiarthroplasty, especially in active individuals with healthy acetabular cartilage. Hemiarthroplasty is often preferred for less active or cognitively impaired patients. Closed reduction and pinning or DHS are typically for non-displaced or impacted femoral neck fractures.

Question 4552

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following is the MOST accurate statement regarding avascular necrosis (AVN) of the femoral head?

. It is always symptomatic and requires immediate surgical intervention.
. Corticosteroid use is a rare risk factor, while trauma is the most common.
. Early diagnosis with plain radiographs is highly sensitive.
. Core decompression is a treatment option primarily for advanced stages with collapse.
. MRI is the most sensitive imaging modality for early detection.

Correct Answer & Explanation

. MRI is the most sensitive imaging modality for early detection.

Explanation

MRI is the most sensitive imaging modality for early detection of avascular necrosis (AVN) of the femoral head, often showing marrow edema and the characteristic 'double line sign' before radiographic changes appear. AVN can be asymptomatic initially. Corticosteroid use and alcohol abuse are significant non-traumatic risk factors, alongside trauma (e.g., femoral neck fracture). Plain radiographs are often normal in early AVN. Core decompression is typically indicated for pre-collapse or early-stage AVN to prevent collapse, not advanced stages.

Question 4553

Topic: 3. Adult Reconstruction (Hip & Knee)

In patients undergoing total knee arthroplasty, what is the MOST common cause of revision surgery within the first 5-10 years?

. Periprosthetic fracture
. Deep vein thrombosis (DVT)
. Polyethylene wear leading to aseptic loosening
. Infection
. Extensor mechanism rupture

Correct Answer & Explanation

. Infection

Explanation

While all options are potential complications, infection is historically one of the most common causes for early revision surgery following total knee arthroplasty (within the first few years and up to 5-10 years). Polyethylene wear leading to aseptic loosening becomes more prevalent in the later stages (10+ years), but infection often necessitates earlier intervention. Periprosthetic fractures and extensor mechanism ruptures are less common overall reasons for revision.

Question 4554

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old female undergoes a total hip arthroplasty via a posterior approach. On postoperative day 2, she complains of acute, severe groin pain and inability to bear weight after attempting to reach for an object on the floor. Her leg is internally rotated, adducted, and shortened. What is the most likely diagnosis?

. Periprosthetic fracture
. Deep vein thrombosis
. Acetabular component loosening
. Posterior hip dislocation
. Infection

Correct Answer & Explanation

. Posterior hip dislocation

Explanation

The presentation of sudden severe groin pain, inability to bear weight, and a classic posture of internal rotation, adduction, and shortening following a posterior approach total hip arthroplasty is pathognomonic for a posterior hip dislocation. The posterior approach is associated with a higher risk of posterior dislocation compared to anterior or direct lateral approaches due to posterior capsule compromise. While other complications are possible, this constellation of signs points directly to dislocation. Periprosthetic fracture would likely present with different deformity and radiographic findings. DVT would present with calf pain and swelling. Acetabular loosening is typically a chronic issue. Infection presents with systemic signs and progressive pain.

Question 4555

Topic: Total Knee Arthroplasty (TKA)

A 15-year-old male presents with chronic anterior knee pain, exacerbated by squatting and prolonged sitting. Examination reveals patellar tenderness and crepitus with patellar motion. Radiographs are unremarkable. What is the most appropriate initial management?

. Arthroscopic debridement and lateral retinacular release
. Quadriceps and hamstring strengthening program
. Patellar realignment surgery
. Corticosteroid injection into the patellofemoral joint
. Activity restriction and NSAIDs only

Correct Answer & Explanation

. Quadriceps and hamstring strengthening program

Explanation

This presentation is classic for patellofemoral pain syndrome (PFPS), also known as chondromalacia patellae, characterized by anterior knee pain, particularly with activities that load the patellofemoral joint. The cornerstone of initial management is a comprehensive physical therapy program focusing on quadriceps strengthening (especially vastus medialis obliquus), hamstring flexibility, and hip abductor strengthening to improve patellar tracking. Activity modification and NSAIDs can provide symptomatic relief but don't address the underlying biomechanical issues. Surgical options are reserved for cases refractory to extensive conservative management. Corticosteroid injections are generally not recommended for PFPS due to limited efficacy and potential cartilage damage.

Question 4556

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following conditions is considered a contraindication to performing a total knee arthroplasty (TKA)?

. Obesity (BMI >40)
. Active knee infection
. Advanced age (>85 years)
. Diabetes mellitus
. History of prior knee surgery

Correct Answer & Explanation

. Active knee infection

Explanation

Active knee infection is an absolute contraindication to total knee arthroplasty (TKA). Performing a TKA in the presence of infection would almost certainly lead to periprosthetic joint infection, which is a devastating complication. The infection must be completely eradicated and confirmed resolved before considering TKA. While obesity, advanced age, diabetes, and prior knee surgery are factors that increase surgical risk or complexity, they are relative contraindications or risk factors, not absolute contraindications. They require careful patient selection and optimization.

Question 4557

Topic: 3. Adult Reconstruction (Hip & Knee)

Regarding avascular necrosis (AVN) of the femoral head, what is the MOST sensitive imaging modality for early detection?

. Plain radiographs (X-rays)
. Computed tomography (CT) scan
. Magnetic resonance imaging (MRI)
. Bone scintigraphy (bone scan)
. Ultrasound

Correct Answer & Explanation

. Magnetic resonance imaging (MRI)

Explanation

Magnetic Resonance Imaging (MRI) is the most sensitive imaging modality for the early detection of avascular necrosis (AVN) of the femoral head. It can detect ischemic changes in the bone marrow before radiographic changes become apparent. Plain radiographs are often normal in the early stages and only show changes (e.g., sclerosis, crescent sign, collapse) in later stages. CT scans offer good bony detail but are less sensitive than MRI for early marrow edema. Bone scintigraphy can be sensitive but lacks specificity. Ultrasound is not typically used for AVN diagnosis.

Question 4558

Topic: 3. Adult Reconstruction (Hip & Knee)

During routine follow-up, a 65-year-old female patient with a history of bilateral total knee arthroplasty (TKA) reports chronic dull aching pain and mild swelling in her left calf, exacerbated by activity. Examination reveals a mild temperature gradient and slight pitting edema, but pulses are normal. Doppler ultrasound is inconclusive. If a diagnosis of chronic exertional compartment syndrome is being considered, what specific measurement technique would be most informative?

. Resting intracompartmental pressure.
. Intracompartmental pressure during exercise.
. Arterial blood pressure at rest and after exercise.
. Venous Doppler flow studies.
. MRI of the calf musculature.

Correct Answer & Explanation

. Intracompartmental pressure during exercise.

Explanation

The definitive diagnosis of chronic exertional compartment syndrome (CECS) relies on dynamic intracompartmental pressure measurements taken before, during, and after exercise. While resting pressures are usually normal in CECS, the pressure significantly increases during exercise and remains elevated for a period afterward (typically >30 mmHg at 1 minute post-exercise or >20 mmHg at 5 minutes post-exercise). Resting pressure alone is insufficient. Arterial blood pressure is systemic and not specific to compartmental pressure. Venous Doppler and MRI might provide other information but are not diagnostic for CECS.

Question 4559

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient with a traumatic femoral head dislocation requires emergent reduction. What is the generally accepted safe time limit for maintaining traction and attempting reduction before considering open reduction, largely due to the risk of avascular necrosis (AVN) related to compromised vascular pressure?

. 2 hours
. 4 hours
. 6 hours
. 8 hours
. 12 hours

Correct Answer & Explanation

. 6 hours

Explanation

Traumatic hip dislocations are orthopedic emergencies due to the high risk of avascular necrosis (AVN) of the femoral head. The incidence of AVN increases significantly with delays in reduction. It is generally accepted that reduction should be achieved within 6 hours (and ideally within 4 hours) of injury to minimize the risk of AVN. Prolonged dislocation causes sustained pressure on and kinking of the retinacular vessels, compromising the blood supply to the femoral head. Beyond this critical time, the risk of irreversible damage to the femoral head vasculature escalates rapidly.

Question 4560

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient undergoes a total knee arthroplasty (TKA). Post-operatively, a continuous passive motion (CPM) machine is used. What is a potential pressure-related benefit of CPM, beyond simply preventing stiffness?

. It directly reduces intra-articular pressure.
. It increases synovial fluid production, which indirectly reduces pressure.
. It promotes venous and lymphatic drainage, reducing swelling and interstitial pressure.
. It increases muscle strength, which stabilizes the joint.
. It improves bone density around the prosthesis.

Correct Answer & Explanation

. It promotes venous and lymphatic drainage, reducing swelling and interstitial pressure.

Explanation

Beyond preventing stiffness, continuous passive motion (CPM) can promote venous and lymphatic drainage, which helps reduce post-operative swelling and interstitial fluid accumulation. By reducing swelling, it can indirectly lower interstitial pressure, potentially improving local tissue perfusion and oxygenation. It does not directly reduce intra-articular pressure (though it might help clear effusions over time) and its primary mechanism isn't increasing synovial fluid or muscle strength immediately.

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