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Pediatric Hip MCQs

Practice Set 91 of 104

This practice set contains high-yield board review questions covering key concepts in Pediatric Hip. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1801

Topic: Pediatric Hip

A 13-year-old obese boy presents with left knee pain, a limp, and obligate external rotation of the left hip with passive flexion. Radiographs confirm a moderate slipped capital femoral epiphysis (SCFE). Which of the following is the most significant risk factor for the subsequent development of a contralateral SCFE?

. Age < 10 years at initial presentation
. Male gender
. Obesity > 95th percentile
. Presentation with an acute-on-chronic slip
. Slip angle > 50 degrees

Correct Answer & Explanation

. Age < 10 years at initial presentation

Explanation

Age less than 10 years at initial presentation (or generally <11 in boys, <10 in girls), open triradiate cartilage, and underlying endocrine disorders are strong predictors for the development of a contralateral SCFE. Prophylactic pinning of the contralateral hip is often recommended in patients meeting these criteria.

Question 1802

Topic: Pediatric Hip

A 4-month-old infant with developmental dysplasia of the hip (DDH) has failed 6 weeks of compliant Pavlik harness treatment, and the affected hip remains completely dislocated and irreducible on ultrasound. What is the most appropriate next step in management?

. Continue Pavlik harness treatment for an additional 4 to 6 weeks
. Switch immediately to a rigid abduction orthosis (e.g., Ilfeld splint)
. Proceed with closed reduction and spica casting under general anesthesia
. Proceed directly to open reduction and capsulorrhaphy
. Perform a proximal femoral varus derotation osteotomy

Correct Answer & Explanation

. Proceed with closed reduction and spica casting under general anesthesia

Explanation

If an infant with DDH fails Pavlik harness treatment (usually defined by 3-4 weeks of complete irreducibility or up to 6 weeks of failure to progress), continued use is contraindicated due to the risk of 'Pavlik harness disease' (erosion of the posterior acetabulum). The standard next step is an examination under anesthesia, arthrogram, and attempted closed reduction with spica casting.

Question 1803

Topic: Pediatric Hip

Which of the following factors is most strongly associated with the development of avascular necrosis (AVN) following surgical pinning of a slipped capital femoral epiphysis (SCFE)?

. Male gender
. Patient obesity
. Unstable slip classification
. Concomitant hyperparathyroidism
. Use of a single cannulated screw

Correct Answer & Explanation

. Unstable slip classification

Explanation

An unstable SCFE, defined clinically by the inability to bear weight even with crutches, carries a high risk of AVN (up to 50%). Other iatrogenic risks include forceful reduction and hardware placed in the superoanterior quadrant.

Question 1804

Topic: Pediatric Hip

A 13-year-old obese male presents with a slipped capital femoral epiphysis (SCFE). If the slip is determined to be unstable, the patient is at highest risk for which of the following complications?

. Chondrolysis
. Osteonecrosis of the femoral head
. Premature osteoarthritis
. Limb length discrepancy
. Femoroacetabular impingement

Correct Answer & Explanation

. Osteonecrosis of the femoral head

Explanation

An unstable SCFE is defined clinically as the inability to bear weight even with crutches. It carries a significantly higher risk of osteonecrosis (avascular necrosis) of the femoral head, reportedly as high as 47%, compared to stable slips.

Question 1805

Topic: Pediatric Hip

A 3-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. Hyperflexion of the hips in the harness places the infant at highest risk for which of the following complications?

. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Sciatic nerve palsy
. Inferior hip dislocation
. Acetabular dysplasia

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion of the hip in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to an iatrogenic femoral nerve palsy (manifesting as decreased active knee extension). Excessive abduction, on the other hand, increases the risk of avascular necrosis (AVN) of the femoral head.

Question 1806

Topic: Pediatric Hip

In the management of Legg-Calve-Perthes disease, the Herring lateral pillar classification relies on radiographs taken during which stage of the disease?

. Initial (Necrosis) stage
. Fragmentation stage
. Reossification stage
. Healed stage
. Remodeling stage

Correct Answer & Explanation

. Fragmentation stage

Explanation

The Herring lateral pillar classification is assessed on an AP radiograph during the fragmentation stage of Legg-Calve-Perthes disease. It evaluates the height of the lateral pillar of the femoral head to determine prognosis and the need for intervention.

Question 1807

Topic: Pediatric Hip

In treating developmental dysplasia of the hip (DDH) with a Pavlik harness, hyperflexion of the hips beyond 120 degrees places the infant at highest risk for which of the following complications?

. Avascular necrosis of the femoral head
. Inferior dislocation of the hip
. Femoral nerve palsy
. Sciatic nerve palsy
. Acetabular dysplasia

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion of the hips in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to transient femoral nerve palsy. Conversely, excessive abduction is the primary risk factor for avascular necrosis.

Question 1808

Topic: Pediatric Hip

In a patient presenting with a slipped capital femoral epiphysis (SCFE), what is the most typical direction of epiphyseal displacement relative to the femoral neck?

. Anterior and superior
. Posterior and inferior
. Anterior and inferior
. Posterior and superior
. Purely lateral

Correct Answer & Explanation

. Posterior and inferior

Explanation

In SCFE, the metaphysis (femoral neck) typically displaces anteriorly and superiorly. This results in the capital femoral epiphysis being anatomically positioned posterior and inferior relative to the neck.

Question 1809

Topic: Pediatric Hip

A 13-year-old obese male presents with acute exacerbation of chronic knee pain and an inability to bear weight. The affected leg is held in external rotation. What is the most severe potential complication of the definitive surgical treatment for his underlying condition?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Premature closure of the triradiate cartilage
. Femoral shaft fracture
. Slipped contralateral epiphysis

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The patient has an unstable Slipped Capital Femoral Epiphysis (SCFE) characterized by the inability to bear weight. The most devastating complication of an unstable SCFE and its surgical stabilization is avascular necrosis (AVN) of the femoral head.

Question 1810

Topic: Pediatric Hip

A 6-month-old female with developmental dysplasia of the hip (DDH) is treated with a Pavlik harness. During a follow-up visit, she demonstrates an inability to actively extend her knee. Which of the following is the most appropriate next step?

. Continue the harness but decrease the hip flexion angle
. Immediate removal of the Pavlik harness
. Apply a rigid hip spica cast
. Perform a closed reduction under general anesthesia
. Perform an open reduction with a pelvic osteotomy

Correct Answer & Explanation

. Immediate removal of the Pavlik harness

Explanation

An inability to actively extend the knee indicates a femoral nerve palsy, a severe complication of the Pavlik harness typically caused by excessive hip flexion. Its occurrence requires the immediate cessation of harness treatment to allow the nerve to recover.

Question 1811

Topic: Pediatric Hip

A 13-year-old obese male presents with left groin pain and a limp for 3 weeks. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). Which of the following physical exam findings is most characteristic of this condition?

. Obligatory internal rotation of the hip with passive flexion
. Obligatory external rotation of the hip with passive flexion
. Increased hip abduction in extension
. Severe pain with passive ankle dorsiflexion
. Positive Trendelenburg sign on the contralateral side

Correct Answer & Explanation

. Obligatory external rotation of the hip with passive flexion

Explanation

Patients with SCFE typically demonstrate obligatory external rotation as the affected hip is passively flexed. This occurs because the femoral neck displaces anteriorly and externally rotates relative to the capital femoral epiphysis.

Question 1812

Topic: Pediatric Hip
A 4-month-old female is diagnosed with Developmental Dysplasia of the Hip (DDH). Ultrasound confirms a dislocated right hip, and treatment with a Pavlik harness is initiated. Which of the following complications is most likely if the hip is maintained in excessive hyperflexion (>120 degrees) in the harness?
. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Obturator nerve palsy
. Sciatic nerve palsy
. Inferior dislocation of the hip

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

In a Pavlik harness, excessive hyperflexion (>120 degrees) is classically associated with femoral nerve palsy due to compression of the nerve against the inguinal ligament. Excessive abduction is associated with avascular necrosis of the femoral head.

Question 1813

Topic: Pediatric Hip

A 13-year-old obese boy presents with right knee pain and a limp. Examination reveals obligate external rotation of the right hip with passive flexion. Slipped Capital Femoral Epiphysis (SCFE) is diagnosed. What is the most common direction of displacement of the proximal femoral epiphysis relative to the femoral neck (metaphysis)?

. Anterior and Superior
. Anterior and Inferior
. Posterior and Superior
. Posterior and Inferior
. Directly Medial

Correct Answer & Explanation

. Posterior and Inferior

Explanation

In SCFE, the femoral neck (metaphysis) typically displaces anteriorly and superiorly relative to the epiphysis. Consequently, the epiphysis is anatomically described as being displaced posteriorly and inferiorly relative to the femoral neck.

Question 1814

Topic: Pediatric Hip

Which of the following underlying conditions is the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip in a 12-year-old patient presenting with a unilateral slipped capital femoral epiphysis (SCFE)?

. Obesity (>95th percentile for BMI)
. Male gender
. Renal osteodystrophy
. African American ethnicity
. Participation in high-impact sports

Correct Answer & Explanation

. Renal osteodystrophy

Explanation

Patients with endocrine or metabolic disorders, such as renal osteodystrophy or hypothyroidism, have a much higher risk of bilateral SCFE. Prophylactic pinning of the contralateral hip is strongly recommended in these atypical presentations.

Question 1815

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, the parents report the infant is no longer actively extending the knee on the treated side. This complication is most commonly associated with which of the following harness positioning errors?

. Excessive hip flexion
. Inadequate hip flexion
. Excessive hip abduction
. Inadequate hip abduction
. Excessive internal rotation

Correct Answer & Explanation

. Excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness and is typically caused by hyperflexion of the hip. In contrast, excessive hip abduction is famously associated with avascular necrosis of the femoral head.

Question 1816

Topic: Pediatric Hip

A 12-year-old obese male presents with acute on chronic slipped capital femoral epiphysis (SCFE). What is the primary blood supply at risk of disruption during surgical pinning?

. Medial femoral circumflex artery
. Lateral femoral circumflex artery
. Ligamentum teres artery
. Inferior gluteal artery
. Superior gluteal artery

Correct Answer & Explanation

. Medial femoral circumflex artery

Explanation

The medial femoral circumflex artery (MFCA), specifically its posterosuperior retinacular branches, is the primary blood supply to the femoral head in this age group and is at high risk of injury in SCFE.

Question 1817

Topic: Pediatric Hip

A 3-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). Hyperflexion of the hip in the harness places the child at highest risk for which of the following complications?

. Femoral nerve palsy
. Sciatic nerve palsy
. Avascular necrosis of the femoral head
. Inferior hip dislocation
. Obturator nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to an iatrogenic femoral nerve palsy. Excessive abduction, conversely, increases the risk of avascular necrosis.

Question 1818

Topic: Pediatric Hip

A 13-year-old overweight male presents with 3 weeks of vague knee pain and an antalgic limp. Examination reveals obligate external rotation of the hip with passive flexion. What is the most severe potential complication of the definitive surgical treatment for his condition?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Femoroacetabular impingement
. Slip progression
. Leg length discrepancy

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The presentation is classic for a slipped capital femoral epiphysis (SCFE). While chondrolysis and impingement are known risks, AVN of the femoral head is the most severe and devastating complication associated with SCFE and surgical pinning.

Question 1819

Topic: Pediatric Hip
A 13-year-old obese male presents with a 3-week history of left knee pain and a limp. He denies any recent trauma or systemic symptoms. On examination, as the left hip is passively flexed, it obligatorily deviates into external rotation. Radiographs of the knee are unremarkable. Which of the following is the most likely underlying pathophysiology of his condition?
. Avascular necrosis of the capital femoral epiphysis
. Shear failure through the hypertrophic zone of the physis
. Bacterial seeding of the hip joint
. Inflammation of the synovial lining of the hip
. Apophysitis of the tibial tubercle

Correct Answer & Explanation

. Shear failure through the hypertrophic zone of the physis

Explanation

The clinical vignette describes slipped capital femoral epiphysis (SCFE), which classically presents in obese adolescents with a painful limp, referred knee pain, and obligate external rotation of the hip during flexion. The underlying pathophysiology of SCFE involves mechanical shear failure through the hypertrophic zone of the physis (growth plate) due to increased mechanical stress (obesity) and hormonal changes during the adolescent growth spurt. Avascular necrosis of the epiphysis describes Legg-Calvรฉ-Perthes disease, which typically affects younger children (ages 4-8).

Question 1820

Topic: Pediatric Hip

A 13-year-old obese male presents with a 2-week history of left groin pain and a limp. He is currently unable to bear weight on the affected limb. Radiographs reveal a slipped capital femoral epiphysis (SCFE). He undergoes urgent in situ percutaneous pinning. Which of the following factors is most strongly associated with the development of avascular necrosis (AVN) of the femoral head in this patient?

. The degree of posterior slip angle greater than 30 degrees.
. The patient's body mass index (BMI) greater than the 95th percentile.
. The inability to bear weight prior to surgical intervention.
. The presence of bilateral SCFE involvement.
. The use of a single screw rather than two screws for fixation.

Correct Answer & Explanation

. The inability to bear weight prior to surgical intervention.

Explanation

Correct Answer: CThe Loder classification categorizes Slipped Capital Femoral Epiphysis (SCFE) into stable and unstable based on the patient's ability to bear weight (with or without crutches). An "unstable" SCFE is defined by the inability to bear weight and carries a significantly higher risk of avascular necrosis (AVN) of the femoral head (up to 47%) compared to stable SCFE, where the AVN rate is typically less than 10%. While slip angle and BMI are important factors in the disease process, stability is the primary prognosticator for AVN.

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