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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 268 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 5341

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old male presents with groin pain and a palpable anterior thigh mass 5 years after receiving a metal-on-metal total hip arthroplasty. Aspiration is negative for infection, but serum cobalt levels are markedly elevated. MRI shows a large cystic solid mass. What is the most appropriate definitive management?

. Observation and repeat MRI in 6 months
. Ultrasound-guided aspiration of the mass
. Revision to a ceramic-on-polyethylene bearing with synovectomy
. Revision of the acetabular component only using a new metal-on-metal bearing
. Oral chelation therapy

Correct Answer & Explanation

. Observation and repeat MRI in 6 months

Explanation

This patient has an adverse local tissue reaction (ALVAL) or pseudotumor from metal-on-metal wear debris. Definitive management requires revision to a non-metal bearing, typically ceramic-on-polyethylene, accompanied by a thorough synovectomy.

Question 5342

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old female sustains a periprosthetic femur fracture 8 years after a primary cementless total hip arthroplasty. Radiographs show a spiral fracture around the stem, and the stem is clearly loose with subsidence. Proximal bone stock is compromised but distal bone stock is adequate. What is the most appropriate surgical treatment?

. Open reduction and internal fixation with a lateral locking plate
. Revision with a long fully porous-coated or fluted tapered stem
. Impaction bone grafting with a cemented stem
. Revision to a proximal femoral replacement
. Strut allografting alone

Correct Answer & Explanation

. Open reduction and internal fixation with a lateral locking plate

Explanation

A Vancouver B2 fracture occurs around a loose stem with adequate distal bone stock. It requires revision to a long bypass stem, such as a fully porous-coated or fluted tapered stem, to achieve secure distal fixation.

Question 5343

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female presents with a painful popping sensation at the superior pole of her patella when extending her knee from a flexed position, 1 year after a posterior-stabilized total knee arthroplasty. What is the most likely etiology of this condition?

. Oversizing of the femoral component
. A fibrous nodule catching in the intercondylar notch of the femoral component
. Patellar component malrotation
. Avascular necrosis of the patella
. Instability of the polyethylene insert

Correct Answer & Explanation

. Oversizing of the femoral component

Explanation

Patellar clunk syndrome occurs in posterior-stabilized knees when a fibrous nodule forms at the superior pole of the patella. This nodule catches in the intercondylar box of the femoral component during active extension.

Question 5344

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient complains of anterior knee pain and lateral patellar subluxation following a primary total knee arthroplasty. CT evaluation of component rotation is performed. Which combination of component malrotation most commonly leads to this specific complication?

. Internal rotation of both the femoral and tibial components
. External rotation of both the femoral and tibial components
. Internal rotation of the femur and external rotation of the tibia
. External rotation of the femur and internal rotation of the tibia
. Coronal varus alignment of the tibial component

Correct Answer & Explanation

. Internal rotation of both the femoral and tibial components

Explanation

Internal rotation of the femoral and tibial components medially displaces the patellar groove and internally rotates the extensor mechanism relative to the tibial tubercle. This increases the Q-angle, leading to lateral patellar maltracking.

Question 5345

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male presents with acute severe knee pain, erythema, and swelling 3 weeks after a primary total knee arthroplasty. Joint aspiration yields 65,000 WBC/uL with 95% neutrophils. Radiographs show well-fixed components. What is the most appropriate management?

. Intravenous antibiotics for 6 weeks without surgery
. Debridement, antibiotics, and implant retention (DAIR) with polyethylene exchange
. Single-stage revision arthroplasty
. Two-stage exchange arthroplasty with an antibiotic spacer
. Arthroscopic irrigation and drainage

Correct Answer & Explanation

. Intravenous antibiotics for 6 weeks without surgery

Explanation

For acute periprosthetic joint infection occurring within 4 weeks of surgery with well-fixed components, DAIR is the standard of care. Modular polyethylene exchange is a mandatory surgical step to effectively reduce the bacterial bioburden.

Question 5346

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total hip arthroplasty, the surgeon opts to use a high-offset femoral stem rather than a standard-offset stem with the same neck length. What is the expected biomechanical effect of this change?

. Increases leg length without affecting abductor tension
. Increases abductor tension without changing leg length
. Decreases the bending moment at the stem-neck junction
. Decreases the risk of greater trochanteric bursitis
. Moves the center of rotation medially

Correct Answer & Explanation

. Increases leg length without affecting abductor tension

Explanation

A high-offset stem increases femoral offset (horizontal distance) without altering the leg length (vertical height). This effectively increases the abductor lever arm, thereby increasing abductor tension and decreasing the overall joint reaction force.

Question 5347

Topic: Total Hip Arthroplasty (THA)

A 45-year-old active male with a ceramic-on-ceramic total hip arthroplasty presents to the ER after hearing a loud "crack" in his hip followed by sudden severe pain. Radiographs confirm a shattered ceramic head. During revision surgery, which of the following steps is critical to prevent early failure of the new bearing?

. Retaining the well-fixed titanium acetabular shell without any liner modifications
. Thorough synovectomy and using a new ceramic head with a titanium sleeve
. Placing a standard metal-on-polyethylene bearing to avoid repeat fracture
. Washing the joint with normal saline and replacing only the femoral head
. Performing a routine extended trochanteric osteotomy

Correct Answer & Explanation

. Retaining the well-fixed titanium acetabular shell without any liner modifications

Explanation

Ceramic fracture generates microscopic third-body shards that rapidly destroy non-ceramic bearings. A thorough synovectomy is critical to remove debris, and a new ceramic head (often with a titanium sleeve if the native trunnion is retained) must be used.

Question 5348

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty, the surgeon uses spacer blocks to assess the gaps. The joint is found to be symmetrically loose in full extension but perfectly balanced at 90 degrees of flexion. Which of the following is the most appropriate next step to correct this mismatch?

. Increase the thickness of the polyethylene insert
. Upsize the femoral component
. Add distal femoral augments
. Release the posterior capsule
. Recut the proximal tibia

Correct Answer & Explanation

. Increase the thickness of the polyethylene insert

Explanation

A joint that is loose in extension but balanced in flexion requires tightening of the extension gap exclusively. Adding distal femoral augments addresses this space deficit without altering the flexion gap.

Question 5349

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old patient with a prior lumbar fusion from L2 to the pelvis is scheduled for a total hip arthroplasty. Preoperative imaging reveals a stiff spinopelvic junction with failure of the pelvis to retrovert when transitioning from standing to sitting. To prevent posterior dislocation during sitting, what adjustment should be made to the acetabular component positioning?

. Decrease cup anteversion and inclination
. Increase cup anteversion and inclination
. Use a constrained liner with standard version
. Increase femoral offset only
. Place the cup in neutral version

Correct Answer & Explanation

. Decrease cup anteversion and inclination

Explanation

A stiff spinopelvic segment fails to retrovert during sitting, depriving the hip of the necessary functional anteversion to accommodate flexion. To compensate and avoid anterior impingement with subsequent posterior dislocation, the surgeon must place the cup in increased operative anteversion and inclination.

Question 5350

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total knee arthroplasty for a severe fixed valgus deformity, the surgeon proceeds with a step-wise soft tissue release. If the knee is found to be tight exclusively in flexion on the lateral side, which of the following structures is the primary tether and should be targeted for release?

. Medial collateral ligament
. Semimembranosus
. Iliotibial band
. Popliteus tendon
. Lateral collateral ligament

Correct Answer & Explanation

. Medial collateral ligament

Explanation

In a valgus knee, the structures on the lateral side contribute variably to gap tightness. The popliteus tendon is the primary lateral stabilizer in flexion, and releasing it addresses isolated flexion gap tightness.

Question 5351

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old male complains of a high-pitched squeaking noise coming from his hip 3 years after a ceramic-on-ceramic total hip arthroplasty. He denies pain, and inflammatory markers are normal. Which of the following factors is most strongly associated with the development of this specific acoustic phenomenon?

. Elevated body mass index (BMI)
. Use of a short femoral trunnion
. Acetabular cup edge loading due to malposition
. Posterior surgical approach
. Use of a 28mm femoral head

Correct Answer & Explanation

. Elevated body mass index (BMI)

Explanation

Squeaking in ceramic-on-ceramic total hip arthroplasty is overwhelmingly linked to mechanical edge loading. This phenomenon most commonly results from acetabular component malpositioning, specifically excessive inclination or insufficient anteversion.

Question 5352

Topic: 3. Adult Reconstruction (Hip & Knee)

A 75-year-old female sustains a fall and presents with severe thigh pain. Radiographs show a periprosthetic fracture around her cementless femoral stem. The stem has subsided 3 cm, but the surrounding proximal femoral bone stock remains robust and intact.

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

. Open reduction and internal fixation with cables alone
. ORIF with a lateral locking plate and allograft struts
. Revision to a standard length cemented stem
. Revision to a long diaphyseal-fitting cementless stem
. Proximal femoral replacement

Correct Answer & Explanation

. Open reduction and internal fixation with cables alone

Explanation

This is a Vancouver B2 fracture, characterized by a loose femoral component in the presence of adequate bone stock. The standard of care is revision arthroplasty using a longer cementless stem (often fluted and tapered) that bypasses the fracture site by at least two cortical diameters.

Question 5353

Topic: 3. Adult Reconstruction (Hip & Knee)

Synovial fluid alpha-defensin testing has emerged as a highly sensitive and specific diagnostic adjunct for periprosthetic joint infection (PJI). What is the physiological origin and function of alpha-defensin?

. A cytokine secreted exclusively by macrophages to recruit T-cells
. An antimicrobial peptide released by neutrophils in response to pathogens
. A biofilm-degrading enzyme produced by Staphylococcus species
. An acute-phase reactant synthesized by the liver during systemic inflammation
. A specific antibody produced by B-lymphocytes against bacterial cell walls

Correct Answer & Explanation

. A cytokine secreted exclusively by macrophages to recruit T-cells

Explanation

Alpha-defensin is a biomarker naturally produced and released by host neutrophils. It functions as an antimicrobial peptide that helps destroy bacterial pathogens within the joint fluid.

Question 5354

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female presents with an audible and palpable 'pop' in her anterior knee that is occasionally painful. This occurs primarily as she actively extends her knee from a seated position following a posterior-stabilized total knee arthroplasty. At what degree of flexion does this 'patellar clunk' classically occur?

. Full extension (0 degrees)
. 10 to 20 degrees of flexion
. 30 to 45 degrees of flexion
. 80 to 90 degrees of flexion
. Beyond 110 degrees of flexion

Correct Answer & Explanation

. Full extension (0 degrees)

Explanation

Patellar clunk syndrome is caused by a fibrous nodule forming at the superior pole of the patella. As the knee actively extends from deep flexion, the nodule catches in the intercondylar notch of the femoral component and abruptly dislodges around 30 to 45 degrees of flexion.

Question 5355

Topic: 3. Adult Reconstruction (Hip & Knee)
A 60-year-old male with a metal-on-metal total hip arthroplasty develops severe groin pain. MRI reveals a large, solid and cystic soft-tissue mass. Serum cobalt and chromium levels are significantly elevated. Which immunological mechanism primarily drives this adverse local tissue reaction (ALVAL)?
. Type I IgE-mediated hypersensitivity
. Type II cytotoxic hypersensitivity
. Type III immune complex-mediated reaction
. Type IV cell-mediated delayed hypersensitivity
. Direct endotoxin-induced macrophage activation

Correct Answer & Explanation

. Type IV cell-mediated delayed hypersensitivity

Explanation

Adverse local tissue reactions (ALTR) or aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL) in metal-on-metal hips are predominantly driven by a Type IV cell-mediated (T-cell) delayed hypersensitivity response to metal wear debris.

Question 5356

Topic: 3. Adult Reconstruction (Hip & Knee)

High peak subsurface contact stresses in historical flat-on-flat total knee arthroplasty designs predominantly led to which specific mechanism of polyethylene failure?

. Abrasive wear
. Adhesive wear
. Delamination wear
. Third-body wear
. Burnishing

Correct Answer & Explanation

. Abrasive wear

Explanation

Older flat-on-flat total knee designs suffered from highly concentrated peak contact stresses that propagated below the polyethylene surface. This mechanism caused subsurface fatigue cracks, classically resulting in delamination and pitting of the polyethylene.

Question 5357

Topic: 3. Adult Reconstruction (Hip & Knee)

An 80-year-old female with severe rheumatoid arthritis undergoes a semi-constrained total elbow arthroplasty (TEA). Postoperatively, which of the following is an absolute permanent weight-lifting restriction typically recommended for this patient?

. 1-2 lbs single event, no repetitive lifting
. 5-10 lbs single event, 1-2 lbs repetitive
. 15-20 lbs single event, 5 lbs repetitive
. 25-30 lbs single event
. No permanent weight restrictions

Correct Answer & Explanation

. 1-2 lbs single event, no repetitive lifting

Explanation

Patients undergoing total elbow arthroplasty (TEA) are subject to permanent lifetime weight restrictions to prevent catastrophic aseptic loosening or bushing wear. The standard recommendation is a 5-10 pound limit for a single event and 1-2 pounds for repetitive lifting.

Question 5358

Topic: 3. Adult Reconstruction (Hip & Knee)

When evaluating a scaphoid proximal pole nonunion, which imaging modality and specific finding is the most sensitive and specific for diagnosing avascular necrosis (AVN) prior to selecting a bone graft type?

. Plain radiographs showing increased sclerosis of the proximal pole
. CT scan showing a humpback deformity
. Gadolinium-enhanced MRI showing absent enhancement of the proximal pole
. Ultrasound showing absent Doppler flow in the anatomical snuffbox
. Bone scan showing intensely increased uptake in the proximal pole

Correct Answer & Explanation

. Plain radiographs showing increased sclerosis of the proximal pole

Explanation

Gadolinium-enhanced MRI is the gold standard for assessing scaphoid vascularity. Absent or significantly decreased enhancement of the proximal pole indicates avascular necrosis, which typically necessitates a vascularized bone graft.

Question 5359

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following MRI sequences and findings is the most reliable preoperative indicator of avascular necrosis (AVN) in a scaphoid proximal pole nonunion?

. High signal intensity on T1-weighted images
. Low signal intensity on T1 and lack of enhancement on gadolinium contrast sequences
. High signal intensity on T2-weighted images with peripheral rim enhancement
. Isointense signal on T1-weighted images relative to the capitate
. Increased signal on STIR sequences isolated to the distal pole

Correct Answer & Explanation

. High signal intensity on T1-weighted images

Explanation

Low signal intensity on T1-weighted imaging combined with a lack of perfusion (no enhancement) following gadolinium contrast administration is the most specific and reliable MRI indicator of proximal pole avascular necrosis.

Question 5360

Topic: Total Hip Arthroplasty (THA)

A 4-year-old boy presents with progressive bowing of his left leg. Radiographs reveal a prominent medial metaphyseal beak, lucency, and an epiphyseal-metaphyseal angle of 20 degrees. What is the most appropriate management?

. Observation and reassurance
. Prescription of a knee-ankle-foot orthosis (KAFO)
. Proximal tibial corrective osteotomy
. Guided growth (hemiepiphysiodesis) of the lateral tibia
. Epiphysiodesis of the contralateral leg to prevent leg length discrepancy

Correct Answer & Explanation

. Observation and reassurance

Explanation

The patient has infantile Blount disease with significant radiographic changes (epiphyseal-metaphyseal angle > 16 degrees). At age 4, bracing is ineffective, making a proximal tibial corrective osteotomy the treatment of choice to prevent permanent deformity.

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