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Pediatric Hip MCQs

Practice Set 57 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 1121

Topic: Pediatric Hip
A 7-year-old boy presents with a painless limp. Radiographs demonstrate sclerosis and fragmentation of the left femoral head. According to the Herring lateral pillar classification for Legg-Calvé-Perthes disease, a patient with >50% but <100% maintenance of lateral pillar height is classified as:
. Group A
. Group B
. Group B/C
. Group C
. Group D

Correct Answer & Explanation

. Group B

Explanation

In the Herring lateral pillar classification, Group B indicates >50% but <100% maintenance of the lateral pillar height. Group C is defined as <50% of the lateral pillar height maintained.

Question 1122

Topic: Pediatric Hip

An 11-year-old boy with obesity presents with 2 weeks of worsening left groin pain and an inability to bear weight that started acutely yesterday. Radiographs confirm an acute-on-chronic slipped capital femoral epiphysis. Which of the following is the most significant risk factor for developing avascular necrosis in this patient?

. Duration of prodromal symptoms
. Severity of the slip angle
. Inability to bear weight at presentation
. Open triradiate cartilage
. Use of a single screw for fixation

Correct Answer & Explanation

. Inability to bear weight at presentation

Explanation

According to the Loder classification, an unstable SCFE is defined by the inability to bear weight, even with crutches. Unstable slips carry a much higher risk of avascular necrosis (up to 47%) compared to stable slips.

Question 1123

Topic: Pediatric Hip

A 6-week-old female is being treated with a Pavlik harness for developmental dysplasia of the hip. During a follow-up visit, the parents note she has stopped kicking her left leg. On exam, there is an absent patellar reflex and lack of active knee extension on the left. What is the most appropriate management?

. Adjust the anterior strap to increase flexion
. Adjust the posterior strap to increase abduction
. Remove the harness and transition to a rigid abduction orthosis
. Remove the harness and observe until neurologic function returns
. Proceed to immediate closed reduction and spica casting

Correct Answer & Explanation

. Remove the harness and observe until neurologic function returns

Explanation

The patient has developed a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The harness must be removed immediately to allow for neurologic recovery, which usually occurs within a few weeks, before resuming DDH treatment.

Question 1124

Topic: Pediatric Hip
An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs reveal fragmentation with maintenance of more than 50% of the lateral pillar height. According to the Herring classification, which group does this represent, and what is the typical recommendation?
. Group A; conservative management
. Group B; surgical containment
. Group B; conservative management
. Group C; surgical containment
. Group C; salvage procedure

Correct Answer & Explanation

. Group B; surgical containment

Explanation

This is a Herring Group B classification (lateral pillar height >50% but <100%). In children over the age of 8, surgical containment (e.g., femoral or pelvic osteotomy) for Group B hips yields better long-term outcomes than conservative management.

Question 1125

Topic: Pediatric Hip

An 11-year-old boy with obesity presents with acute left groin pain and inability to bear weight after a minor fall. He has a 3-week history of mild limp. Radiographs confirm an unstable slipped capital femoral epiphysis (SCFE). In addition to urgent in situ pinning of the left hip, what is the most appropriate management regarding the contralateral hip?

. Observation with clinical follow-up only
. Routine prophylactic pinning of the right hip
. Prophylactic pinning of the right hip only if the modified Oxford bone age score is low
. Immediate open reduction of the left hip and prophylactic pinning of the right hip
. Bilateral spica casting

Correct Answer & Explanation

. Prophylactic pinning of the right hip only if the modified Oxford bone age score is low

Explanation

Prophylactic pinning of the contralateral hip is indicated in patients with a high risk of a second slip, such as those with endocrine disorders or significant remaining growth (e.g., modified Oxford bone age score <= 16). Routine prophylactic pinning without risk stratification is not universally recommended.

Question 1126

Topic: Pediatric Hip

An 18-month-old girl is brought in for a waddling gait. Radiographs reveal a completely dislocated left hip with a false acetabulum and an acetabular index of 42 degrees. What is the most appropriate management?

. Pavlik harness application
. Closed reduction and spica casting
. Open reduction, femoral shortening, and pelvic osteotomy
. Arthroscopic debridement and reduction
. Observation until age 3

Correct Answer & Explanation

. Open reduction, femoral shortening, and pelvic osteotomy

Explanation

Children presenting with DDH between 18 and 24 months of age typically require open reduction due to soft tissue contractures and acetabular dysplasia. Concomitant femoral shortening minimizes avascular necrosis risk, and a pelvic osteotomy corrects the severe acetabular dysplasia.

Question 1127

Topic: Pediatric Hip
An 8-year-old boy presents with a 6-month history of right hip pain and a painless limp. AP and frog-leg lateral radiographs show sclerosis and fragmentation of the lateral pillar of the femoral head. Dynamic arthrogram demonstrates hinge abduction. What is the most appropriate management?
. Observation and non-weight bearing
. A-frame bracing
. Adductor tenotomy and petrie cast application
. Proximal femoral varus osteotomy or pelvic osteotomy
. Core decompression

Correct Answer & Explanation

. Proximal femoral varus osteotomy or pelvic osteotomy

Explanation

In Legg-Calvé-Perthes disease, hinge abduction is a sign of severe impingement between the extruded, deformed femoral head and the lateral acetabular margin. Surgical containment via proximal femoral or pelvic osteotomy is required to redirect the head into the acetabulum and restore congruity.

Question 1128

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 32 presents with an acute-on-chronic stable left slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic pinning of the contralateral asymptomatic hip?

. Age less than 10 years or greater than 16 years
. Presence of an endocrine disorder such as hypothyroidism
. Severe slip angle (> 60 degrees) on the affected side
. Presentation with an unstable SCFE
. Male sex and high body mass index alone

Correct Answer & Explanation

. Presence of an endocrine disorder such as hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly indicated in patients with underlying endocrine disorders (such as hypothyroidism or renal osteodystrophy) or prior radiation therapy, as they are at a markedly increased risk of bilateral involvement.

Question 1129

Topic: Pediatric Hip

A 6-week-old girl is being treated with a Pavlik harness for developmental dysplasia of the hip. At her 2-week follow-up, she is noted to have decreased active extension of the knee on the treated side. Which of the following is the most appropriate next step?

. Abandon the harness and proceed to closed reduction and spica casting
. Adjust the anterior straps to decrease hip flexion
. Adjust the posterior straps to increase hip abduction
. Obtain an MRI of the lumbar spine
. Refer for electromyography (EMG)

Correct Answer & Explanation

. Adjust the anterior straps to decrease hip flexion

Explanation

Decreased active knee extension indicates a femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness. Management consists of adjusting the anterior straps to decrease hip flexion or temporarily removing the harness if symptoms persist.

Question 1130

Topic: Pediatric Hip

A 6-week-old female is undergoing treatment with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 1-week follow-up, the parents report she has stopped kicking her left leg. On examination, there is decreased active extension of the left knee, but normal ankle movements. What is the most appropriate next step in management?

. Perform a formal ultrasound of the hip
. Adjust the anterior straps to increase hip flexion
. Temporarily discontinue the harness and observe
. Switch to a rigid hip spica cast
. Refer for nerve conduction studies

Correct Answer & Explanation

. Temporarily discontinue the harness and observe

Explanation

Decreased active knee extension indicates a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The harness should be temporarily removed until nerve function recovers.

Question 1131

Topic: Pediatric Hip

A 12-year-old boy presents with left knee pain and a limp. Radiographs confirm a stable left slipped capital femoral epiphysis (SCFE). Which of the following is the most accepted indication for prophylactic pinning of the contralateral asymptomatic hip?

. Patient age older than 14 years
. Presentation with a stable SCFE on the affected side
. Presence of an underlying endocrine disorder
. Male sex
. Body mass index greater than 95th percentile

Correct Answer & Explanation

. Presence of an underlying endocrine disorder

Explanation

Prophylactic pinning of the contralateral hip is strongly considered in patients with underlying endocrine disorders, renal failure, or who are very young, due to a high risk of bilateral involvement.

Question 1132

Topic: Pediatric Hip

An 8-month-old female presents with an untreated developmental dysplasia of the hip (DDH) with a dislocated left hip. What is the most appropriate initial management?

. Pavlik harness
. Rigid abduction orthosis
. Closed reduction and spica casting
. Open reduction and spica casting
. Open reduction and femoral shortening osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

For DDH presenting between 6 and 18 months of age, closed reduction and spica casting is the initial treatment of choice. The Pavlik harness is typically ineffective after 6 months of age.

Question 1133

Topic: Pediatric Hip

A 13-year-old obese boy presents to the emergency department unable to bear weight on his right leg after a minor slip. He reports a 3-month history of mild right knee pain. Examination shows the right hip resting in external rotation. Which of the following complications is most highly associated with this acute presentation?

. Chondrolysis
. Avascular necrosis
. Femoroacetabular impingement
. Premature osteoarthritis
. Leg length discrepancy

Correct Answer & Explanation

. Avascular necrosis

Explanation

This patient has an unstable slipped capital femoral epiphysis (SCFE), defined by the inability to bear weight. Unstable SCFE carries a significantly higher risk of avascular necrosis (up to 47%) compared to stable SCFE.

Question 1134

Topic: Pediatric Hip

A 7-year-old boy has been limping for 6 months and is diagnosed with Legg-Calve-Perthes disease. Radiographs show fragmentation of the femoral head. Which of the following radiographic findings represents the poorest prognostic factor?

. Coxa magna
. Intact lateral pillar
. Lateral subluxation of the femoral head
. Sclerosis of the epiphysis
. Widening of the medial joint space

Correct Answer & Explanation

. Lateral subluxation of the femoral head

Explanation

Lateral subluxation (extrusion) of the femoral head is a major "head at risk" sign and a poor prognostic factor in Perthes disease. It can lead to hinge abduction, resulting in severe deformity and early osteoarthritis.

Question 1135

Topic: Pediatric Hip

A 12-year-old obese boy presents to the emergency department with severe right groin pain and an inability to bear weight on his right leg after a minor fall. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). He undergoes urgent in situ pinning. Which of the following complications is most highly associated with this patient's specific type of presentation?

. Avascular necrosis (AVN)
. Chondrolysis
. Subtrochanteric femur fracture
. Deep space infection
. Implant failure

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

This patient has an unstable SCFE, defined by the inability to bear weight even with crutches. Unstable SCFE has a significantly higher rate of avascular necrosis (up to 20-50%) compared to stable SCFE, regardless of the treatment method used.

Question 1136

Topic: Pediatric Hip

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During the follow-up visit, the parents report that the infant is no longer actively extending the knee on the treated side. On examination, there is decreased spontaneous movement of the quadriceps. What is the most appropriate next step in management?

. Loosen the anterior straps of the harness
. Loosen the posterior straps of the harness
. Immediately abandon the harness and switch to a spica cast
. Order an urgent MRI of the lumbar spine
. Continue the current settings and observe for another 2 weeks

Correct Answer & Explanation

. Loosen the anterior straps of the harness

Explanation

The infant presents with a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The appropriate management is to loosen the anterior straps to decrease hip flexion, which usually leads to spontaneous resolution of the palsy.

Question 1137

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease (LCPD). Which of the following factors at the time of presentation is considered the most significant predictor of a poor long-term radiographic outcome?
. Age of onset greater than 8 years
. Male gender
. Herring Lateral Pillar group A classification
. Loss of internal rotation less than 15 degrees
. Involvement of the medial aspect of the epiphysis

Correct Answer & Explanation

. Age of onset greater than 8 years

Explanation

Age at onset is a critical prognostic factor in LCPD; children older than 8 years generally have a worse prognosis and a higher risk of developing residual deformity and secondary osteoarthritis. The Herring Lateral Pillar classification is also highly prognostic, but Group A represents a good outcome.

Question 1138

Topic: Pediatric Hip

Figure 37 shows a radiograph of a 13-year-old presenting with hip pain.

To assess for the condition seen, a line is drawn along the superior aspect of the femoral neck. In a normal hip, this line intersects the lateral aspect of the epiphysis. What is the eponymous sign when this line fails to intersect the epiphysis?

. Trethowan sign
. Crescent sign
. Sagging rope sign
. Throckmorton sign
. Hilgenreiner's sign

Correct Answer & Explanation

. Trethowan sign

Explanation

The line described is Klein's line. In slipped capital femoral epiphysis (SCFE), Klein's line passes completely superior to the epiphysis rather than intersecting it; this finding is known as the Trethowan sign.

Question 1139

Topic: Pediatric Hip

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, it is noted that the harness is adjusted with excessive hip flexion. This specific malposition is most associated with which of the following complications?

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

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Excessive hip flexion in a Pavlik harness can cause impingement leading to a femoral nerve palsy. In contrast, excessive abduction is classically associated with avascular necrosis of the femoral head.

Question 1140

Topic: Pediatric Hip

A 13-year-old obese boy presents with a stable slipped capital femoral epiphysis (SCFE) of the left hip. What is the most established primary indication for prophylactic pinning of the asymptomatic contralateral hip?

. Modified Southwick angle greater than 60 degrees
. Age less than 10 years at presentation or an underlying endocrinopathy
. Body mass index (BMI) greater than the 95th percentile
. Unstable presentation of the index slip
. Triradiate cartilage closure on presentation

Correct Answer & Explanation

. Age less than 10 years at presentation or an underlying endocrinopathy

Explanation

Prophylactic pinning of the contralateral hip is generally recommended for patients younger than 10 years or those with underlying endocrine disorders (e.g., hypothyroidism). These patients have a significantly higher risk of developing bilateral involvement.

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