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Pediatric Hip MCQs

Practice Set 103 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 2041

Topic: Pediatric Hip
In the management of a 7-year-old child with Legg-Calvé-Perthes disease, which radiographic classification system, applied during the fragmentation phase, is recognized as the most reliable predictor of long-term hip prognosis?
. Catterall classification
. Salter-Thompson classification
. Herring Lateral Pillar classification
. Stulberg classification
. Waldenström stages

Correct Answer & Explanation

. Herring Lateral Pillar classification

Explanation

The Herring Lateral Pillar classification, which evaluates the height of the lateral third of the capital femoral epiphysis during the fragmentation phase, is the most accurate and widely used prognostic indicator for Legg-Calvé-Perthes disease.

Question 2042

Topic: Pediatric Hip

A 6-week-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up ultrasound, the anterior strap is noted to be excessively tight, forcing the hip into hyperflexion. Which of the following complications is she at highest risk of developing due to this specific strap positioning?

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

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Excessive flexion in a Pavlik harness (caused by anterior straps being too tight) places the patient at risk for femoral nerve palsy by compressing the nerve against the inguinal ligament. In contrast, excessive abduction (posterior straps too tight) increases the risk of avascular necrosis of the femoral head.

Question 2043

Topic: Pediatric Hip

A 7-year-old boy is diagnosed with Legg-Calve-Perthes disease. When evaluating his pelvic radiographs, the treating orthopedic surgeon utilizes the Herring classification. Which specific anatomical feature is assessed in this classification system to determine the prognosis?

. Extent of subchondral fracture (crescent sign)
. Height of the lateral pillar of the capital femoral epiphysis
. Degree of metaphyseal cyst formation
. Percentage of femoral head coverage by the acetabulum
. Amount of medial joint space widening

Correct Answer & Explanation

. Height of the lateral pillar of the capital femoral epiphysis

Explanation

The Herring classification system for Legg-Calve-Perthes disease evaluates the height of the lateral pillar of the capital femoral epiphysis on an AP radiograph during the fragmentation stage. A preserved lateral pillar (>50% height) generally correlates with a better long-term outcome.

Question 2044

Topic: Pediatric Hip

A 7-year-old boy presents with bilateral hip pain and a waddling gait. Radiographs reveal bilateral, symmetric fragmentation and flattening of the capital femoral epiphyses, along with irregularity of the acetabula. Radiographs of the spine are entirely normal. Which of the following is the most likely diagnosis?

. Legg-Calve-Perthes disease
. Multiple Epiphyseal Dysplasia
. Spondyloepiphyseal Dysplasia
. Meyer Dysplasia

Correct Answer & Explanation

. Multiple Epiphyseal Dysplasia

Explanation

Correct Answer: Multiple Epiphyseal DysplasiaMultiple Epiphyseal Dysplasia (MED) is characterized by delayed and irregular ossification of the epiphyses. It is distinguished from Legg-Calve-Perthes disease by its bilateral, symmetric nature and the presence of acetabular involvement (Perthes typically has a normal acetabulum initially and is often unilateral or asymmetric). The normal spine differentiates MED from Spondyloepiphyseal Dysplasia (SED), which features platyspondyly.

Question 2045

Topic: Pediatric Hip

A 2-year-old boy undergoes a pelvic radiograph following a minor fall. He is completely asymptomatic. The radiograph incidentally reveals delayed and irregular ossification of bilateral capital femoral epiphyses. There is no involvement of other joints. The condition is expected to resolve spontaneously. What is the diagnosis?

. Multiple Epiphyseal Dysplasia
. Legg-Calve-Perthes disease
. Meyer dysplasia
. Hypothyroidism

Correct Answer & Explanation

. Meyer dysplasia

Explanation

Correct Answer: Meyer dysplasiaMeyer dysplasia (dysplasia epiphysealis capitis femoris) is a localized dysplasia of the capital femoral epiphysis characterized by delayed, irregular ossification. It is typically asymptomatic, discovered incidentally in toddlers (usually around age 2), and resolves spontaneously without treatment. It must be differentiated from Perthes disease, which presents later (age 4-8) with pain and necrosis.

Question 2046

Topic: Pediatric Hip
A 2-year-old boy is incidentally found to have delayed and irregular ossification of bilateral capital femoral epiphyses on a pelvic radiograph taken for a suspected hernia. He has no limp, normal range of motion, and no pain. What is the most appropriate management?
. Bilateral proximal femoral varus derotation osteotomies
. Petrie cast application
. Observation and reassurance
. Core decompression of the femoral heads
. Genetic testing for COL2A1 mutation

Correct Answer & Explanation

. Observation and reassurance

Explanation

Meyer dysplasia (dysplasia epiphysealis capitis femoris) is a localized dysplasia of the femoral head characterized by delayed, irregular ossification. It typically presents in children around 2 years of age, is often bilateral, and is asymptomatic. It resolves spontaneously without intervention by age 5-6. It is crucial to differentiate this from Legg-Calvé-Perthes disease, which presents later (4-8 years) with pain, limp, and requires closer monitoring or intervention.

Question 2047

Topic: Pediatric Hip

A 7-year-old boy with a known COL2A1 mutation presents with a short trunk, barrel chest, and severe coxa vara. Given his underlying diagnosis of Spondyloepiphyseal Dysplasia Congenita, he should be routinely screened by an ophthalmologist to prevent which of the following complications?

. Glaucoma
. Cataracts
. Retinal detachment
. Optic nerve hypoplasia
. Macular degeneration

Correct Answer & Explanation

. Retinal detachment

Explanation

Correct Answer: C (Retinal detachment)Spondyloepiphyseal Dysplasia Congenita (SEDC) is a type II collagenopathy caused by mutations in the COL2A1 gene. Type II collagen is a major structural component of the vitreous humor of the eye. Patients are highly susceptible to high myopia and retinal detachment, necessitating regular ophthalmologic screening to prevent blindness.

Question 2048

Topic: Pediatric Hip
A 3-year-old boy is incidentally found to have delayed and irregular ossification of bilateral capital femoral epiphyses on a pelvic radiograph taken for a suspected urinary tract infection. He has no limp and no hip pain. Which of the following statements best differentiates this condition from Legg-Calvé-Perthes disease?
. This condition typically presents with severe, unrelenting night pain.
. This condition requires urgent surgical containment to prevent joint destruction.
. This condition shows a fragmented appearance that resolves spontaneously without epiphyseal collapse.
. This condition is inherited in an autosomal dominant pattern.
. This condition primarily affects children older than 8 years.

Correct Answer & Explanation

. This condition shows a fragmented appearance that resolves spontaneously without epiphyseal collapse.

Explanation

The clinical scenario describes Meyer dysplasia, a benign, often asymptomatic condition characterized by delayed and irregular ossification of the capital femoral epiphysis. It typically presents in children aged 2 to 3 years and is frequently bilateral. Unlike Legg-Calvé-Perthes disease, Meyer dysplasia does not progress to epiphyseal collapse or severe deformity, and it resolves spontaneously without the need for surgical containment or bracing.

Question 2049

Topic: Pediatric Hip
A 6-year-old child is evaluated for bilateral hip pain and a waddling gait. Radiographs show delayed, fragmented ossification of both capital femoral epiphyses. Which of the following radiographic findings would most strongly support a diagnosis of Multiple Epiphyseal Dysplasia (MED) rather than bilateral Legg-Calvé-Perthes disease?
. Unilateral subchondral crescent sign
. Metaphyseal cysts in the proximal femur
. A double-layered appearance of the patella on a lateral knee radiograph
. Severe platyspondyly of the thoracic spine
. Coxa magna deformity

Correct Answer & Explanation

. A double-layered appearance of the patella on a lateral knee radiograph

Explanation

Differentiating MED from bilateral Legg-Calvé-Perthes disease can be challenging as both present with fragmented, irregular capital femoral epiphyses. However, MED is a systemic dysplasia affecting multiple epiphyses. A classic radiographic hallmark of MED is the 'double patella' (a double-layered appearance of the patella on a lateral knee radiograph), which is seen in a significant percentage of patients. Severe platyspondyly (Option D) would suggest Spondyloepiphyseal Dysplasia (SED), as the spine is typically normal or only mildly affected in MED. Crescent signs and coxa magna are common in Perthes disease.

Question 2050

Topic: Pediatric Hip
A 2-year-old boy is incidentally found to have delayed and irregular ossification of the bilateral capital femoral epiphyses on a pelvic radiograph taken for a suspected swallowed coin. He has no limp, normal range of motion, and no pain. What is the most appropriate management for this orthopedic finding?
. Bilateral proximal femoral varus derotational osteotomies
. Application of an abduction orthosis
. Core decompression of the femoral heads
. Observation and reassurance
. Genetic testing for the COL2A1 mutation

Correct Answer & Explanation

. Observation and reassurance

Explanation

The clinical scenario describes Meyer dysplasia (dysplasia epiphysealis capitis femoris), which is characterized by delayed and irregular ossification of the capital femoral epiphyses. It typically presents incidentally in toddlers (usually around 2 years of age) and is bilateral in about 50% of cases. Unlike Legg-Calvé-Perthes disease, Meyer dysplasia is a benign, self-limiting condition that does not progress to avascular necrosis or collapse. Therefore, the most appropriate management is observation and reassurance. No surgical or orthotic intervention is required.

Question 2051

Topic: Pediatric Hip
A 2-year-old boy is incidentally found to have delayed and granular ossification of the bilateral capital femoral epiphyses on a pelvic radiograph taken for a suspected urinary tract infection. He has no limp, no hip pain, and a completely normal range of motion. What is the most appropriate management for this orthopedic finding?
. Bilateral proximal femoral varus derotation osteotomies
. Application of an abduction orthosis (e.g., Atlanta brace)
. Core decompression of the femoral heads
. Observation and reassurance
. Genetic testing for COL2A1 mutation

Correct Answer & Explanation

. Observation and reassurance

Explanation

This presentation is highly characteristic of Meyer dysplasia (dysplasia epiphysealis capitis femoris). It is a benign, self-limiting condition characterized by delayed and irregular ossification of the capital femoral epiphysis. It is typically bilateral, asymptomatic, and discovered incidentally in toddlers. It is crucial to differentiate it from Legg-Calvé-Perthes disease, which usually presents later (ages 4-8) with pain and a limp. Meyer dysplasia requires no treatment and typically resolves with normal ossification by age 6.

Question 2052

Topic: Pediatric Hip
A 2-year-old boy is brought in for a mild waddling gait. Radiographs show delayed, irregular ossification of both capital femoral epiphyses without metaphyseal cysts, subchondral fractures, or acetabular abnormalities. The spine is unaffected. By age 5, follow-up radiographs show near-complete resolution. What is the most likely diagnosis?
. Legg-Calvé-Perthes disease
. Multiple Epiphyseal Dysplasia
. Spondyloepiphyseal Dysplasia Congenita
. Hypothyroidism
. Meyer dysplasia

Correct Answer & Explanation

. Meyer dysplasia

Explanation

Meyer dysplasia is a self-limiting condition characterized by delayed and irregular ossification of the capital femoral epiphysis, typically presenting around age 2. Unlike Legg-Calvé-Perthes disease, it lacks metaphyseal cysts or subchondral fractures and normalizes without surgical intervention.

Question 2053

Topic: Pediatric Hip

A 9-year-old girl presents with bilateral hip stiffness and a waddling gait. Radiographs show delayed ossification and flattening of the capital femoral epiphyses. Which of the following radiographic features best distinguishes Multiple Epiphyseal Dysplasia (MED) from bilateral Legg-Calve-Perthes disease?

. Unilateral involvement
. Presence of metaphyseal cysts
. Symmetrical bilateral involvement without varying stages of healing
. Presence of a subchondral fracture (crescent sign)
. Development of coxa magna

Correct Answer & Explanation

. Symmetrical bilateral involvement without varying stages of healing

Explanation

MED typically presents with highly symmetrical bilateral epiphyseal changes. In contrast, bilateral Legg-Calve-Perthes disease is almost always asynchronous, presenting in varying stages of necrosis and healing between the two hips.

Question 2054

Topic: Pediatric Hip

A 13-year-old obese male presents with a 3-week history of left knee pain and a noticeable limp. He denies any recent trauma. On examination, his left leg is externally rotated, and he has obligatory external rotation when the hip is flexed to 90 degrees. Radiographs confirm a posterior and inferior displacement of the proximal femoral epiphysis. Which of the following is the most appropriate definitive management to prevent further displacement while minimizing the risk of avascular necrosis?

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

Correct Answer & Explanation

. In situ fixation with a single cannulated screw

Explanation

Correct Answer: CThe patient has a stable Slipped Capital Femoral Epiphysis (SCFE), which frequently presents with referred knee pain and obligatory external rotation during hip flexion. The standard of care for a stable SCFE is in situ fixation, typically with a single central cannulated screw, to prevent further slippage. Closed reduction is strictly contraindicated as it significantly increases the risk of avascular necrosis (AVN) of the femoral head by disrupting the already tenuous retinacular blood supply.

Question 2055

Topic: Pediatric Hip

A 13-year-old obese male presents with left knee pain and an obligatory external rotation of the hip during passive flexion. Radiographs confirm a slipped capital femoral epiphysis (SCFE). During the pathomechanical process of this condition, what is the true displacement of the femoral head (epiphysis) relative to the femoral neck (metaphysis)?

. The epiphysis displaces anteriorly and superiorly.
. The epiphysis displaces anteriorly and inferiorly.
. The metaphysis displaces anteriorly and superiorly, while the epiphysis remains in the acetabulum.
. The metaphysis displaces posteriorly and inferiorly, while the epiphysis remains in the acetabulum.
. The epiphysis displaces laterally and superiorly.

Correct Answer & Explanation

. The metaphysis displaces anteriorly and superiorly, while the epiphysis remains in the acetabulum.

Explanation

Correct Answer: The metaphysis displaces anteriorly and superiorly, while the epiphysis remains in the acetabulum.Although the term "slipped capital femoral epiphysis" implies that the epiphysis is the structure that moves, the biomechanical reality is the opposite. The femoral epiphysis is held securely within the acetabulum by the ligamentum teres. The mechanical failure occurs through the hypertrophic zone of the physis, allowing the femoral neck (metaphysis) to displace anteriorly, superiorly, and externally rotate relative to the fixed epiphysis. This creates the classic radiographic appearance of a posterior and inferior "slip" of the epiphysis on the AP and lateral views.

Question 2056

Topic: Pediatric Hip

An infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the parents report the child is no longer kicking the affected leg. On examination, the knee lacks active extension. Which of the following positioning errors most likely caused this complication?

. Excessive hip flexion
. Excessive hip extension
. Excessive hip abduction
. Excessive hip adduction
. Inadequate hip flexion

Correct Answer & Explanation

. Excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive hip flexion. It presents with absent active knee extension and usually resolves with temporary removal or adjustment of the harness.

Question 2057

Topic: Pediatric Hip

A 4-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. At her 2-week follow-up, her mother reports that the infant is no longer actively kicking her left leg. On examination, there is an absence of active knee extension on the left, but active ankle motion is intact. Which of the following is the most likely cause?

. Avascular necrosis of the femoral head
. Inferior dislocation of the hip
. Femoral nerve palsy due to excessive hip flexion
. Obturator nerve palsy due to excessive hip abduction
. Developmental coxa vara

Correct Answer & Explanation

. Femoral nerve palsy due to excessive hip flexion

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. The immediate treatment is to adjust the harness to decrease the degree of hip flexion.

Question 2058

Topic: Pediatric Hip

A 4-month-old female is currently being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 2-week follow-up, the parents note that she is no longer kicking her right leg. On physical examination, the right knee lacks active extension, but active ankle and toe movements are completely intact. What is the most likely etiology of this finding, and what is the most appropriate next step in management?

. Transient femoral nerve palsy from excessive hip flexion; adjust the harness to decrease flexion.
. Ischemic necrosis of the femoral head from hyperabduction; immediate surgical release.
. Sciatic nerve palsy from excessive hip extension; permanently discontinue the harness.
. Transient obturator nerve palsy from excessive abduction; adjust the anterior straps.
. Acute compartment syndrome of the thigh; emergent fasciotomy.

Correct Answer & Explanation

. Transient femoral nerve palsy from excessive hip flexion; adjust the harness to decrease flexion.

Explanation

Excessive hip flexion in a Pavlik harness can compress the femoral nerve, causing a transient femoral nerve palsy that presents as a loss of active knee extension. The appropriate management is to adjust the anterior straps to decrease the degree of hip flexion, which typically results in full neurologic recovery.

Question 2059

Topic: Pediatric Hip

A 10-year-old boy is diagnosed with developmental coxa vara. Biomechanically, how does this deformity alter the forces acting on the proximal femur?

. It decreases the bending moment across the femoral neck and increases the abductor moment arm.
. It increases the bending moment across the femoral neck and decreases the abductor moment arm.
. It increases the bending moment across the femoral neck and increases the abductor moment arm.
. It decreases the bending moment across the femoral neck and decreases the abductor moment arm.
. It decreases both the joint reaction force and the bending moment across the femoral neck.

Correct Answer & Explanation

. It increases the bending moment across the femoral neck and increases the abductor moment arm.

Explanation

Coxa vara decreases the neck-shaft angle, which anatomically lengthens the abductor moment arm, improving abductor efficiency. However, it also creates a longer perpendicular distance from the load vector to the neck, increasing the bending moment and the risk of fracture.

Question 2060

Topic: Pediatric Hip

A patient develops coxa vara following a malunited intertrochanteric fracture. How does this structural deformity primarily alter hip biomechanics?

. Increases the abductor moment arm and increases shear stress across the femoral neck.
. Decreases the abductor moment arm and decreases shear stress.
. Decreases the abductor moment arm and increases shear stress.
. Increases the body weight moment arm and decreases shear stress.
. Decreases joint reaction force and decreases shear stress.

Correct Answer & Explanation

. Decreases the abductor moment arm and increases shear stress.

Explanation

Coxa vara decreases the neck-shaft angle, which lengthens the abductor moment arm (improving abductor mechanical advantage) but significantly increases shear forces across the femoral neck, risking nonunion or failure.

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