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Pediatric Hip MCQs

Practice Set 85 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 1681

Topic: Pediatric Hip
According to the lateral pillar classification for Legg-Calvé-Perthes disease described by Herring, during which radiographic stage of the disease should the classification be applied to most accurately determine prognosis?
. Initial (necrosis) stage
. Fragmentation stage
. Reossification (healing) stage
. Residual stage
. At the onset of clinical symptoms regardless of radiographic stage

Correct Answer & Explanation

. Fragmentation stage

Explanation

The Herring lateral pillar classification evaluates the height of the lateral pillar of the capital femoral epiphysis (Group A >100%, Group B >50%, Group C <50%). It is most accurately assessed and most prognostic when applied during the fragmentation stage of Legg-Calvé-Perthes disease, when the full extent of the structural collapse is evident.

Question 1682

Topic: Pediatric Hip

A 4-month-old infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the parents note that the infant has stopped kicking with the affected leg. On examination, the hip is found to be in excessive flexion. Which of the following physical exam findings is most likely to be present?

. Inability to actively flex the hip
. Inability to actively extend the knee
. Inability to actively dorsiflex the ankle
. Inability to actively plantarflex the ankle
. Absent Achilles reflex

Correct Answer & Explanation

. Inability to actively extend the knee

Explanation

A known complication of treating DDH with a Pavlik harness in excessive hip flexion is femoral nerve palsy. This manifests as a loss of quadriceps function, leading to the inability to actively extend the knee. The treatment is temporary removal of the harness or adjustment to decrease the degree of hip flexion. Excessive abduction, conversely, increases the risk of avascular necrosis (AVN) of the femoral head.

Question 1683

Topic: Pediatric Hip

A 12-year-old girl with a history of severe hypothyroidism presents with a limp and left hip pain. Radiographs reveal a slipped capital femoral epiphysis (SCFE) of the left hip. What is the most appropriate definitive management?

. In situ pinning of the left hip only
. Open reduction and internal fixation of the left hip
. In situ pinning of the left hip and prophylactic pinning of the right hip
. Spica cast immobilization
. Proximal femoral osteotomy of the left hip

Correct Answer & Explanation

. In situ pinning of the left hip and prophylactic pinning of the right hip

Explanation

While unilateral SCFE is typically treated with single-screw in situ pinning, prophylactic pinning of the contralateral asymptomatic hip is strongly recommended in patients with specific risk factors. These high-risk factors include underlying endocrine disorders (such as hypothyroidism, panhypopituitarism), renal osteodystrophy, and a history of previous pelvic radiation. Given her severe hypothyroidism, prophylactic pinning of the right hip is indicated.

Question 1684

Topic: Pediatric Hip

A 13-year-old obese boy presents with knee pain and an antalgic gait. Examination reveals obligatory external rotation of the hip with passive flexion. What is the most appropriate initial treatment if radiographs confirm a stable Slipped Capital Femoral Epiphysis (SCFE)?

. Closed reduction and spica casting
. In situ pinning with a single cannulated screw
. Open reduction and internal fixation
. Proximal femoral osteotomy
. Observation and non-weight bearing

Correct Answer & Explanation

. In situ pinning with a single cannulated screw

Explanation

The standard of care for a stable SCFE is in situ pinning with a single, partially threaded cannulated screw placed centrally in the epiphysis. Closed reduction is contraindicated due to the high risk of disrupting the blood supply and causing osteonecrosis.

Question 1685

Topic: Pediatric Hip

A 13-year-old obese boy presents with progressive left knee pain and an antalgic gait. Examination reveals obligatory external rotation of the hip during passive flexion. Which of the following is the most appropriate initial management?

. Physical therapy for hip abductor strengthening
. Non-weight bearing and immediate orthopedic referral for in situ pinning
. Closed reduction and spica casting
. Open reduction and internal fixation
. Proximal femoral osteotomy

Correct Answer & Explanation

. Non-weight bearing and immediate orthopedic referral for in situ pinning

Explanation

The clinical presentation is classic for a Slipped Capital Femoral Epiphysis (SCFE). The standard of care is immediate non-weight bearing to prevent further slippage, followed by in situ percutaneous screw fixation.

Question 1686

Topic: Pediatric Hip

A 4-month-old female infant is diagnosed with developmental dysplasia of the hip (DDH) that is reducible. A Pavlik harness is prescribed. Which of the following represents the most serious complication of excessive hyperflexion of the hips in the harness?

. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Obturator nerve palsy
. Inferior dislocation of the hip
. Knee flexion contracture

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Excessive hyperflexion in a Pavlik harness can lead to femoral nerve palsy. Avascular necrosis is typically a complication of excessive rigid abduction, while femoral nerve palsy is the classic risk of excessive flexion.

Question 1687

Topic: Pediatric Hip

A 4-week-old infant is being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). Excessive hyperflexion of the hips in the harness most commonly risks injury to which of the following nerves?

. Sciatic nerve
. Obturator nerve
. Superior gluteal nerve
. Femoral nerve
. Lateral femoral cutaneous nerve

Correct Answer & Explanation

. Femoral nerve

Explanation

Excessive flexion in a Pavlik harness (greater than 100-120 degrees) can compress the femoral nerve against the inguinal ligament, leading to transient femoral nerve palsy. Excessive abduction, on the other hand, risks avascular necrosis.

Question 1688

Topic: Pediatric Hip

A 13-year-old obese male presents with a 3-week history of vague right groin and knee pain. He walks with an antalgic limp. On physical examination, as his right hip is passively flexed, it obligatorily falls into external rotation. Radiographs confirm the diagnosis. Which of the following is the gold standard initial management?

. Application of a hip spica cast in internal rotation
. In situ pinning with a single cannulated screw
. Open reduction and internal fixation through a Smith-Petersen approach
. Closed reduction and percutaneous pinning
. Proximal femoral osteotomy to correct the deformity

Correct Answer & Explanation

. In situ pinning with a single cannulated screw

Explanation

The clinical presentation is classic for a slipped capital femoral epiphysis (SCFE). In situ pinning with a single cannulated screw placed in the center of the epiphysis is the gold standard to prevent further slippage.

Question 1689

Topic: Pediatric Hip

A 4-month-old female with developmental dysplasia of the hip (DDH) has been treated with a Pavlik harness for 4 weeks. Serial ultrasounds confirm that the hip remains dislocated despite verifiable compliance and proper harness application. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 4 weeks
. Transition to a rigid abduction orthosis (e.g., Ilfeld splint)
. Perform an immediate open reduction and capsulorrhaphy
. Perform a closed reduction and application of a spica cast under general anesthesia
. Observe and delay treatment until the child begins walking

Correct Answer & Explanation

. Transition to a rigid abduction orthosis (e.g., Ilfeld splint)

Explanation

If a Pavlik harness fails to achieve reduction after 3 to 4 weeks, continuing it increases the risk of 'Pavlik harness disease' (erosion of the posterior acetabulum). The next appropriate non-operative step is transitioning to a rigid abduction orthosis.

Question 1690

Topic: Pediatric Hip

A 13-year-old obese boy presents with left thigh pain and a limp for 3 weeks. Examination reveals obligatory external rotation of the left hip with passive flexion. He is diagnosed with a slipped capital femoral epiphysis (SCFE). Which of the following is a strong indication for prophylactic pinning of the contralateral, asymptomatic hip?

. Age greater than 14 years
. Male gender
. Presence of an underlying endocrine disorder
. Body mass index > 95th percentile
. Acute on chronic presentation

Correct Answer & Explanation

. Presence of an underlying endocrine disorder

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended for patients with underlying endocrine disorders (such as hypothyroidism or renal osteodystrophy) due to the exceedingly high risk of bilateral involvement. Routine prophylactic pinning in idiopathic cases remains controversial.

Question 1691

Topic: Pediatric Hip

A 13-year-old obese male presents with left knee pain and a limp. Radiographs reveal a slipped capital femoral epiphysis (SCFE). He undergoes in-situ percutaneous pinning. Which of the following factors places this patient at the highest risk for developing post-operative chondrolysis?

. Unrecognized initial severity of the slip
. Unrecognized pin penetration into the joint space
. The patient's elevated Body Mass Index (BMI)
. Delayed diagnosis of the condition
. An underlying endocrine abnormality

Correct Answer & Explanation

. Unrecognized pin penetration into the joint space

Explanation

Chondrolysis is a devastating complication of SCFE characterized by acute cartilage destruction. The most significant iatrogenic risk factor for chondrolysis is unrecognized pin penetration into the joint space during in-situ fixation. While severe slips and immobilization are also risk factors, intra-articular hardware strongly correlates with this complication.

Question 1692

Topic: Pediatric Hip

A 4-week-old female is diagnosed with developmental dysplasia of the hip (DDH) and is placed in a Pavlik harness. During a follow-up visit, the infant is noted to have a lack of active knee extension. Which specific harness misapplication is most likely responsible for this nerve palsy?

. Inadequate hip abduction
. Excessive hip hyperflexion
. Excessive hip hyperabduction
. Excessive hip extension
. Excessive internal rotation

Correct Answer & Explanation

. Excessive hip hyperflexion

Explanation

Excessive hip flexion (hyperflexion) in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a temporary femoral nerve palsy characterized by a lack of active knee extension. Excessive hip abduction places the infant at a higher risk for avascular necrosis (AVN) of the femoral head.

Question 1693

Topic: Pediatric Hip

A 6-week-old female infant, born breech, undergoes a screening hip ultrasound. The alpha angle is measured at 45 degrees, and the beta angle is 80 degrees. What is the most appropriate next step in management?

. Reassurance and repeat ultrasound in 3 months
. Application of a Pavlik harness
. Closed reduction and spica casting
. Open reduction and capsulorrhaphy
. Application of an abduction brace for night use only

Correct Answer & Explanation

. Application of a Pavlik harness

Explanation

An alpha angle less than 60 degrees on a Graf ultrasound indicates developmental dysplasia of the hip (DDH). The standard initial treatment for a reducible dysplastic hip in an infant under 6 months is a Pavlik harness.

Question 1694

Topic: Pediatric Hip
In a 7-year-old boy diagnosed with Legg-Calvé-Perthes disease, which of the following radiographic findings constitutes the most significant prognostic factor for a poor outcome?
. Presence of a subchondral fracture (Crescent sign)
. Involvement of the medial pillar
. Lateral pillar involvement of greater than 50%
. Enlargement of the femoral head (coxa magna)
. Widening of the medial joint space

Correct Answer & Explanation

. Lateral pillar involvement of greater than 50%

Explanation

The Herring Lateral Pillar classification is the most reliable prognostic indicator for Legg-Calvé-Perthes disease. Group C (greater than 50% collapse of the lateral pillar) is highly predictive of a poor outcome.

Question 1695

Topic: Pediatric Hip

An infant treated with a Pavlik harness for developmental dysplasia of the hip (DDH) is noted to have decreased spontaneous active extension of the knee on the treated side. Which of the following is the most likely iatrogenic cause?

. Avascular necrosis of the femoral head
. Obturator nerve palsy from excessive abduction
. Femoral nerve palsy from excessive hyperflexion
. Sciatic nerve palsy from excessive internal rotation
. Inferior soft tissue impingement preventing relocation

Correct Answer & Explanation

. Femoral nerve palsy from excessive hyperflexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive hip hyperflexion compressing the nerve. It presents as an inability to actively extend the knee, and management involves adjusting the harness to reduce the degree of flexion.

Question 1696

Topic: Pediatric Hip
In the evaluation of a 7-year-old boy with Legg-Calvé-Perthes disease, the lateral pillar classification is used to predict outcome and guide management. During which radiographic stage of the disease should the lateral pillar classification be definitively determined?
. Initial (necrosis) stage
. Early fragmentation stage
. Late fragmentation stage
. Reossification stage
. Healed stage

Correct Answer & Explanation

. Early fragmentation stage

Explanation

The Herring lateral pillar classification evaluates the remaining height of the lateral pillar of the femoral head to accurately predict the long-term prognosis. It is most accurately and reliably assessed during the early fragmentation stage of the disease process.

Question 1697

Topic: Pediatric Hip

When evaluating a 6-week-old infant for developmental dysplasia of the hip (DDH) using the Graf ultrasound method, what anatomical landmark does the alpha angle evaluate, and what is considered a normal value?

. Cartilaginous roof; greater than 55 degrees
. Bony roof; greater than 60 degrees
. Cartilaginous roof; less than 43 degrees
. Bony roof; less than 50 degrees
. Labrum; greater than 60 degrees

Correct Answer & Explanation

. Bony roof; greater than 60 degrees

Explanation

The alpha angle measures the acetabular bony roof concavity relative to the ilium. An alpha angle greater than or equal to 60 degrees is considered normal (Graf Type I).

Question 1698

Topic: Pediatric Hip

The lateral pillar classification is crucial for determining the prognosis of Legg-Calve-Perthes disease. This classification evaluates the height of the lateral pillar of the capital femoral epiphysis on which specific radiographic view?

. Frog-leg lateral
. Cross-table lateral
. Anteroposterior (AP) pelvis
. False profile view
. Dunn view

Correct Answer & Explanation

. Anteroposterior (AP) pelvis

Explanation

The Herring lateral pillar classification relies on the AP pelvis radiograph during the fragmentation phase of the disease. It assesses the height of the lateral third of the epiphysis compared to the contralateral normal hip.

Question 1699

Topic: Pediatric Hip
A 6-year-old boy presents with a painless limp and restricted hip abduction. Radiographs show fragmentation of the femoral head consistent with Legg-Calvé-Perthes disease. According to the Herring lateral pillar classification, a hip maintaining exactly 60% of lateral pillar height falls into which group?
. Group A
. Group B
. Group B/C
. Group C
. Group D

Correct Answer & Explanation

. Group B

Explanation

In the Herring lateral pillar classification, Group A has no lateral pillar involvement, Group B maintains >50% of lateral pillar height, and Group C has <50% of the lateral pillar height maintained.

Question 1700

Topic: Pediatric Hip

A 6-week-old infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. At the 1-week follow-up, the mother notes the infant has stopped kicking the affected leg. On examination, there is an absent patellar reflex on the affected side. What is the most appropriate next step in management?

. Continue the harness and observe for 1 week
. Discontinue the harness immediately
. Adjust the anterior strap to increase flexion
. Adjust the posterior strap to decrease abduction
. Switch to a rigid hip spica cast

Correct Answer & Explanation

. Discontinue the harness immediately

Explanation

The clinical presentation is classic for a femoral nerve palsy, a known complication of Pavlik harness treatment due to excessive hyperflexion of the hip. The immediate and most appropriate treatment is to discontinue the harness until motor function returns, after which an alternative bracing strategy or a modified harness application may be considered.

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