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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 318 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 6341

Topic: Total Hip Arthroplasty (THA)

When using the Paley Multiplier Method to predict leg length discrepancy (LLD) at skeletal maturity, the multiplier coefficient is primarily determined by the patient's:

. Chronological age and gender
. Bone age and current weight
. Skeletal maturity score on a pelvis radiograph (Risser sign)
. Current limb length and desired lengthening amount
. Bone age and gender

Correct Answer & Explanation

. Chronological age and gender

Explanation

The Paley Multiplier Method relies on chronological age and gender to find the specific multiplier coefficient. This coefficient is then multiplied by the current LLD to accurately predict the discrepancy at skeletal maturity.

Question 6342

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old active female presents with isolated, symptomatic lateral compartment knee osteoarthritis and a 12-degree valgus mechanical axis deviation. The optimal surgical procedure to unload the lateral compartment is:

. Medial opening-wedge high tibial osteotomy
. Medial closing-wedge distal femoral osteotomy
. Lateral closing-wedge high tibial osteotomy
. Unicompartmental knee arthroplasty of the medial compartment
. Total knee arthroplasty

Correct Answer & Explanation

. Medial closing-wedge distal femoral osteotomy

Explanation

For valgus deformities localized to the femur causing lateral compartment overload, a distal femoral osteotomy (classically a medial closing-wedge or lateral opening-wedge) is the treatment of choice. Tibial osteotomies for large valgus deformities can induce problematic joint line obliquity.

Question 6343

Topic: 3. Adult Reconstruction (Hip & Knee)

A 12-year-old girl undergoes temporary hemiepiphysiodesis for genu varum. Following complete correction, the plates are removed. Her parents should be counseled about which of the following potential complications regarding longitudinal growth?

. Permanent growth arrest is expected in all cases after 1 year of implantation.
. Rebound deformity, which occurs in up to 15% of cases, often necessitating close follow-up.
. Overgrowth of the limb causing significant leg length discrepancy.
. Avascular necrosis of the proximal tibial epiphysis.
. Premature closure of the entire physis due to plate irritation.

Correct Answer & Explanation

. Rebound deformity, which occurs in up to 15% of cases, often necessitating close follow-up.

Explanation

Rebound growth is a well-documented phenomenon following the removal of tension band plates, particularly in younger children with significant growth remaining. Close follow-up is necessary to monitor for recurrence.

Question 6344

Topic: 3. Adult Reconstruction (Hip & Knee)

A 75-year-old woman sustains a displaced intracapsular femoral neck fracture. She is at high risk for developing avascular necrosis of the femoral head due to disruption of its primary blood supply. Which of the following arteries is the predominant source of vascularity to the weight-bearing portion of the adult femoral head?

. Artery of the ligamentum teres
. Lateral circumflex femoral artery
. Medial circumflex femoral artery
. Inferior gluteal artery
. First perforating branch of the profunda femoris

Correct Answer & Explanation

. Medial circumflex femoral artery

Explanation

Correct Answer: Medial circumflex femoral arteryThe medial circumflex femoral artery (MCFA) is the dominant blood supply to the adult femoral head. It gives rise to the lateral epiphyseal artery, which supplies the critical weight-bearing superolateral portion of the femoral head. Displaced intracapsular femoral neck fractures frequently tear these retinacular vessels, leading to a high incidence of avascular necrosis. The artery of the ligamentum teres provides a negligible amount of blood supply in adults.

Question 6345

Topic: 3. Adult Reconstruction (Hip & Knee)

The medial circumflex femoral artery (MCFA) provides the primary blood supply to the adult femoral head. During a posterior approach to the hip (Moore or Southern approach), the main branch of the MCFA is most at risk of iatrogenic injury during the surgical release of which of the following structures?

. Piriformis tendon
. Gluteus maximus insertion
. Quadratus femoris muscle
. Obturator internus tendon
. Gluteus medius muscle

Correct Answer & Explanation

. Quadratus femoris muscle

Explanation

Correct Answer: Quadratus femoris muscleThe medial circumflex femoral artery (MCFA) is the dominant blood supply to the femoral head. Its ascending branch runs deep to the quadratus femoris and along its superior border. During a posterior approach to the hip, releasing the quadratus femoris too far medially or aggressively can result in iatrogenic injury to the MCFA, potentially compromising the blood supply to the femoral head and increasing the risk of avascular necrosis.

Question 6346

Topic: 3. Adult Reconstruction (Hip & Knee)

The medial circumflex femoral artery (MCFA) is the dominant blood supply to the adult femoral head. Which specific branch of the MCFA is most critical for perfusing the weight-bearing superolateral aspect of the femoral head?

. Anterior retinacular artery
. Inferior gluteal artery
. Lateral epiphyseal artery
. Artery of the ligamentum teres
. Descending branch of the lateral circumflex femoral artery

Correct Answer & Explanation

. Lateral epiphyseal artery

Explanation

Correct Answer: Lateral epiphyseal arteryThe lateral epiphyseal artery system, which arises from the posterosuperior retinacular branches of the medial circumflex femoral artery (MCFA), provides the majority of the blood supply to the weight-bearing superolateral portion of the femoral head. Injury to these vessels during a femoral neck fracture leads to avascular necrosis.

Question 6347

Topic: 3. Adult Reconstruction (Hip & Knee)

A 35-year-old man sustains a displaced, completely off-ended, intracapsular femoral neck fracture (Garden IV) after a high-altitude fall. Disruption of which of the following blood vessels is the primary cause of the high rate of avascular necrosis in this specific injury?

. Artery of the ligamentum teres
. Medial femoral circumflex artery
. Lateral femoral circumflex artery
. Inferior gluteal artery
. First perforating branch of the profunda femoris

Correct Answer & Explanation

. Medial femoral circumflex artery

Explanation

The medial femoral circumflex artery (MFCA), specifically its lateral epiphyseal branches, is the predominant blood supply to the adult femoral head. Disruption of this vessel in displaced femoral neck fractures leads to a high rate of avascular necrosis.

Question 6348

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old woman is scheduled for a total hip arthroplasty. The surgeon opts to use a highly cross-linked polyethylene (HXLPE) liner. Which of the following is the primary advantage of HXLPE compared to conventional ultra-high molecular weight polyethylene?

. Decreased risk of liner fracture
. Increased resistance to oxidative degradation
. Decreased volumetric wear
. Increased elasticity and toughness
. Elimination of backside wear

Correct Answer & Explanation

. Decreased volumetric wear

Explanation

Highly cross-linked polyethylene (HXLPE) significantly reduces volumetric wear and subsequent osteolysis compared to conventional polyethylene. However, the cross-linking process and subsequent irradiation can decrease its ultimate tensile strength and toughness.

Question 6349

Topic: 3. Adult Reconstruction (Hip & Knee)

Four years after a total knee arthroplasty, a 68-year-old man presents with new-onset joint pain and swelling. Synovial fluid aspiration yields a white blood cell count of 45,000 cells/mcL with 92% polymorphonuclear leukocytes. Which of the following is the most appropriate definitive management?

. Intravenous antibiotics for 6 weeks without surgery
. Arthroscopic irrigation and debridement
. Open irrigation and debridement with polyethylene exchange
. Two-stage revision arthroplasty
. Single-stage revision with antibiotic-impregnated cement

Correct Answer & Explanation

. Two-stage revision arthroplasty

Explanation

This patient has a chronic periprosthetic joint infection (PJI) occurring years after the index procedure. The gold standard definitive treatment for a late chronic PJI in the United States is a two-stage revision arthroplasty utilizing an antibiotic spacer.

Question 6350

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male presents with groin pain 5 years after a metal-on-metal total hip arthroplasty. MRI shows a complex cystic mass communicating with the joint space. What histologic finding is most characteristic of this specific pathology?

. Abundant polymorphonuclear leukocytes
. Negatively birefringent needle-shaped crystals
. Diffuse lymphocytic infiltration with perivascular cuffing
. Multinucleated giant cells containing polyethylene debris
. Aseptic necrosis of the trabecular bone

Correct Answer & Explanation

. Diffuse lymphocytic infiltration with perivascular cuffing

Explanation

Metal-on-metal implants can fail due to ALVAL (aseptic lymphocyte-dominated vasculitis-associated lesion). Histology typically demonstrates a diffuse perivascular lymphocytic infiltration, distinguishing it from polyethylene wear (macrophages/giant cells) or infection (neutrophils).

Question 6351

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty, the surgeon notes that the joint is excessively tight in flexion but perfectly balanced in extension. Which of the following is the most appropriate surgical step to correct this mismatch?

. Resect more distal femur
. Downsize the femoral component while maintaining the anterior cut
. Upsize the femoral component
. Release the posterior capsule
. Decrease the posterior slope of the tibial cut

Correct Answer & Explanation

. Downsize the femoral component while maintaining the anterior cut

Explanation

A knee that is tight in flexion and balanced in extension requires an isolated increase in the flexion gap. Downsizing the femoral component utilizing an anterior referencing system removes more posterior condylar bone, opening the flexion gap without altering the extension gap.

Question 6352

Topic: 3. Adult Reconstruction (Hip & Knee)

In total hip arthroplasty, highly cross-linked polyethylene (HXLPE) is often utilized to decrease wear rates. Which of the following material properties is most significantly decreased as a direct result of the irradiation process used to cross-link the polyethylene?

. Ultimate tensile strength
. Elastic modulus
. Hardness
. Volumetric wear
. Fatigue resistance

Correct Answer & Explanation

. Fatigue resistance

Explanation

While irradiation creates cross-links that dramatically reduce volumetric wear, it inherently decreases the material's fatigue resistance, ductility, and fracture toughness. Subsequent melting or annealing is required to eliminate free radicals, which further alters mechanical properties.

Question 6353

Topic: 3. Adult Reconstruction (Hip & Knee)

A 42-year-old man presents with chronic knee pain and mechanical symptoms. Radiographs show multiple intra-articular calcific bodies of uniform size. What is the most appropriate management for symptomatic primary synovial chondromatosis of the knee?

. Observation and NSAIDs
. Intra-articular corticosteroid injection
. Removal of loose bodies and synovectomy
. Total knee arthroplasty
. Radiation therapy

Correct Answer & Explanation

. Removal of loose bodies and synovectomy

Explanation

The standard of care for symptomatic primary synovial chondromatosis without severe secondary osteoarthritis is complete removal of the loose bodies combined with synovectomy to reduce the risk of recurrence.

Question 6354

Topic: 3. Adult Reconstruction (Hip & Knee)

Patients with advanced ankylosing spondylitis undergoing total hip arthroplasty (THA) are at a significantly higher risk for which of the following postoperative complications compared to patients with primary osteoarthritis?

. Periprosthetic joint infection
. Heterotopic ossification
. Aseptic loosening of the femoral component
. Intraoperative femur fracture
. Polyethylene wear

Correct Answer & Explanation

. Heterotopic ossification

Explanation

Patients with ankylosing spondylitis have a strong systemic tendency for new bone formation, placing them at a significantly elevated risk for severe heterotopic ossification following THA. Prophylaxis with NSAIDs or radiation is strongly recommended.

Question 6355

Topic: 3. Adult Reconstruction (Hip & Knee)

A 42-year-old male with long-standing ankylosing spondylitis

has severe bilateral hip pain and stiffness and is scheduled for a total hip arthroplasty (THA). Which of the following is the most significant perioperative concern specific to his disease?

. High risk of aseptic loosening
. Difficult intubation due to cervical rigidity
. Increased risk of periprosthetic joint infection
. Propensity for severe postoperative bleeding
. High risk of implant fracture

Correct Answer & Explanation

. Difficult intubation due to cervical rigidity

Explanation

Patients with ankylosing spondylitis frequently have cervical spine rigidity and deformity, making intubation extremely difficult and posing a risk for iatrogenic cervical fractures. Anesthesia must be carefully planned, often requiring awake fiberoptic intubation.

Question 6356

Topic: 3. Adult Reconstruction (Hip & Knee)

A 40-year-old woman is diagnosed with primary synovial chondromatosis of the hip. She complains of progressive pain, catching, and limited range of motion. What is the recommended definitive surgical treatment to minimize recurrence?

. Diagnostic arthroscopy and lavage only
. Open or arthroscopic loose body removal with extensive synovectomy
. Core decompression of the femoral head
. Total hip arthroplasty
. Intra-articular injection of chemical synoviorthesis

Correct Answer & Explanation

. Open or arthroscopic loose body removal with extensive synovectomy

Explanation

The standard treatment for primary synovial chondromatosis involves the removal of all loose bodies combined with an extensive synovectomy to remove the metaplastic synovium and reduce the recurrence rate.

Question 6357

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old male with severe hip pain secondary to ankylosing spondylitis is scheduled for a total hip arthroplasty (THA). Compared to a patient with primary osteoarthritis, this patient is at a significantly higher risk for which of the following postoperative complications?

. Aseptic loosening of the femoral stem
. Periprosthetic joint infection
. Heterotopic ossification
. Sciatic nerve palsy
. Periprosthetic femur fracture

Correct Answer & Explanation

. Heterotopic ossification

Explanation

Patients with ankylosing spondylitis are at a high risk for developing heterotopic ossification following THA. Prophylaxis with NSAIDs (e.g., Indomethacin) or low-dose localized radiation is generally recommended.

Question 6358

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following is considered the standard surgical management for a symptomatic patient with primary synovial chondromatosis of the knee to minimize the risk of recurrence?

. Arthroscopic removal of loose bodies only
. Arthroscopic or open removal of loose bodies with extensive synovectomy
. Total knee arthroplasty
. Intra-articular corticosteroid injection followed by physical therapy
. External beam radiation to the synovium

Correct Answer & Explanation

. Arthroscopic or open removal of loose bodies with extensive synovectomy

Explanation

The standard treatment for primary synovial chondromatosis is the removal of all loose bodies combined with an extensive synovectomy. Removing the loose bodies alone without addressing the metaplastic synovium leads to high recurrence rates.

Question 6359

Topic: 3. Adult Reconstruction (Hip & Knee)

A 35-year-old male with ankylosing spondylitis is scheduled for a total hip arthroplasty (THA) due to severe bilateral hip involvement. He is at significantly increased risk for which of the following postoperative complications compared to patients with primary osteoarthritis?

. Aseptic loosening of the femoral stem
. Periprosthetic joint infection
. Heterotopic ossification
. Recurrent posterior instability
. Sciatic nerve palsy

Correct Answer & Explanation

. Heterotopic ossification

Explanation

Patients with ankylosing spondylitis undergoing THA have a notoriously high risk of developing postoperative heterotopic ossification (HO). Prophylaxis with postoperative NSAIDs or low-dose radiation should be strongly considered in these cases.

Question 6360

Topic: 3. Adult Reconstruction (Hip & Knee)

A 35-year-old male with severe ankylosing spondylitis requires bilateral total hip arthroplasties (THA) for end-stage auto-fusion of his hips. Postoperatively, this patient is at the highest risk for which of the following complications?

. Aseptic loosening of the femoral component
. Recurrent dislocation
. Heterotopic ossification
. Periprosthetic joint infection
. Intraoperative periprosthetic fracture

Correct Answer & Explanation

. Heterotopic ossification

Explanation

Patients with ankylosing spondylitis undergoing THA have a significantly higher risk of developing heterotopic ossification compared to the general population. Routine prophylaxis with NSAIDs or radiation is highly recommended.

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