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Pediatric Hip MCQs

Practice Set 97 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 1921

Topic: Pediatric Hip
In the evaluation of a 7-year-old boy with Legg-Calvé-Perthes disease, the treating orthopedic surgeon utilizes the Herring lateral pillar classification to determine prognosis. During which stage of the disease is this classification system most accurately applied?
. Initial (necrosis) stage
. Early fragmentation stage
. Late fragmentation stage
. Reossification stage
. Residual stage

Correct Answer & Explanation

. Early fragmentation stage

Explanation

The Herring lateral pillar classification is used to predict the outcome in Legg-Calvé-Perthes disease. It is based on the height of the lateral pillar of the capital femoral epiphysis on an AP radiograph. It is most accurately applied during the early fragmentation stage of the disease. Applying it too early (in the initial stage) may underestimate the extent of lateral pillar involvement and lead to an inaccurate prognosis.

Question 1922

Topic: Pediatric Hip

In a patient with a Slipped Capital Femoral Epiphysis (SCFE), the proximal femoral epiphysis typically displaces in which direction relative to the femoral neck?

. Anterior and superior
. Anterior and inferior
. Posterior and inferior
. Posterior and superior
. Directly medial

Correct Answer & Explanation

. Posterior and inferior

Explanation

Correct Answer: C (Posterior and inferior)In SCFE, the femoral neck displaces anteriorly and superiorly relative to the epiphysis. Therefore, the epiphysis is displaced posteriorly and inferiorly relative to the femoral neck. This biomechanical relationship dictates the typical external rotation deformity and obligate external rotation with hip flexion seen clinically.

Question 1923

Topic: Pediatric Hip
In the evaluation of a 7-year-old boy with Legg-Calvé-Perthes disease, the Herring Lateral Pillar classification is used to determine prognosis. This classification is based on the radiolucency and height of the lateral pillar of the femoral head during which stage of the disease?
. Initial (necrosis) stage
. Fragmentation stage
. Reossification stage
. Residual stage
. Pre-collapse stage

Correct Answer & Explanation

. Fragmentation stage

Explanation

The Herring Lateral Pillar classification is the most widely used prognostic classification for Legg-Calvé-Perthes disease. It evaluates the height of the lateral pillar of the capital femoral epiphysis on an AP pelvic radiograph during the fragmentation stage of the disease, as this is when the maximum extent of epiphyseal collapse is evident.

Question 1924

Topic: Pediatric Hip

A 13-year-old obese boy presents with groin pain and an obligate external rotation of the hip during flexion. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following best describes the anatomical displacement of the femoral neck relative to the capital epiphysis in this condition?

. The neck displaces posteriorly and inferiorly.
. The neck displaces anteriorly and superiorly.
. The neck displaces anteriorly and inferiorly.
. The neck displaces posteriorly and superiorly.
. The neck displaces medially and inferiorly.

Correct Answer & Explanation

. The neck displaces anteriorly and superiorly.

Explanation

Correct Answer: The neck displaces anteriorly and superiorly.In Slipped Capital Femoral Epiphysis (SCFE), the capital femoral epiphysis remains relatively fixed in the acetabulum while the femoral neck displaces anteriorly and superiorly. This biomechanical shift leads to the classic clinical presentation of obligate external rotation when the hip is flexed.

Question 1925

Topic: Pediatric Hip

During open reduction of Developmental Dysplasia of the Hip (DDH) via an anterior approach, several anatomical structures must be addressed to allow concentric reduction. Which of the following is NOT typically considered an anatomical block to reduction in DDH?

. Inverted limbus
. Hypertrophied ligamentum teres
. Fibrofatty pulvinar
. Tight iliopsoas tendon
. Shortened piriformis tendon

Correct Answer & Explanation

. Shortened piriformis tendon

Explanation

Obstacles to reduction in DDH include the inverted limbus, hypertrophied ligamentum teres, pulvinar, tight iliopsoas tendon, and transverse acetabular ligament. The piriformis is located posteriorly and is not typically a block to reduction.

Question 1926

Topic: Pediatric Hip

An 11-year-old obese male presents to the emergency department unable to bear weight on his left leg after a minor slip. Radiographs confirm a severe left slipped capital femoral epiphysis (SCFE). Which of the following factors is most predictive of developing avascular necrosis (AVN) of the femoral head in this patient?

. Body Mass Index (BMI) greater than 35
. Degree of posterior epiphyseal slip greater than 50%
. Inability to bear weight with or without crutches
. Delay in surgical pinning beyond 24 hours
. Prophylactic pinning of the contralateral hip

Correct Answer & Explanation

. Inability to bear weight with or without crutches

Explanation

The inability to bear weight defines an unstable SCFE according to the Loder classification. Unstable SCFE has a significantly higher risk of developing AVN (up to 50%) compared to stable SCFE, regardless of slip severity.

Question 1927

Topic: Pediatric Hip

A 6-week-old female is being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). During follow-up, she exhibits decreased active extension of the knee on the affected side. What is the most appropriate next step in management?

. Immediate closed reduction and spica casting
. Adjust the harness to increase hip flexion
. Discontinue the harness temporarily or adjust it to decrease hip flexion
. Continue current harness settings and re-evaluate in 2 weeks
. Perform an ultrasound-guided intra-articular steroid injection

Correct Answer & Explanation

. Discontinue the harness temporarily or adjust it 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. The harness should be adjusted to decrease flexion or temporarily removed until nerve function recovers.

Question 1928

Topic: Pediatric Hip

A 10-year-old boy with chronic renal failure presents with a limp and obligate external rotation of the hip during flexion. Radiographs confirm a moderate stable slipped capital femoral epiphysis (SCFE). In addition to pinning the affected hip, what is the primary indication for prophylactic pinning of the contralateral hip?

. Age older than 12 years
. Male gender
. Presence of an underlying endocrine or metabolic disorder
. Severity of the initial slip angle
. Body mass index > 95th percentile

Correct Answer & Explanation

. Presence of an underlying endocrine or metabolic disorder

Explanation

Patients with SCFE associated with endocrinopathies or metabolic disorders (like renal failure, hypothyroidism) have a very high risk of bilateral involvement. Prophylactic pinning of the contralateral hip is highly recommended in these specific populations.

Question 1929

Topic: Pediatric Hip

A 7-year-old boy is diagnosed with Legg-Calve-Perthes disease. According to the lateral pillar (Herring) classification, which radiographic feature in the fragmentation stage portends the worst prognosis?

. Maintenance of 100% of lateral pillar height
. Lateral pillar height >50% but <100%
. Lateral pillar height <50% of original height
. Central pillar collapse with an intact lateral pillar
. Involvement of the medial pillar only

Correct Answer & Explanation

. Lateral pillar height <50% of original height

Explanation

The Herring Lateral Pillar classification predicts the outcome of Legg-Calve-Perthes disease based on the height of the lateral pillar during the fragmentation stage. Group C (<50% lateral pillar height maintained) indicates severe collapse and carries the worst prognosis.

Question 1930

Topic: Pediatric Hip

A 3-month-old female with developmental dysplasia of the hip (DDH) has been treated in a Pavlik harness for two weeks. Her mother reports that the baby is no longer kicking her right leg. Examination reveals absent active knee extension on the right, but ankle and toe movements are normal. What is the most likely cause of this finding?

. Avascular necrosis of the femoral head
. Obturator nerve palsy due to extreme abduction
. Femoral nerve palsy due to hyperflexion
. Sciatic nerve palsy due to extreme abduction
. Tibial nerve palsy due to posterior strap tightness

Correct Answer & Explanation

. Femoral nerve palsy due to hyperflexion

Explanation

Femoral nerve palsy is the most common neurologic complication associated with the Pavlik harness, typically resulting from hyperflexion of the hip. Management consists of adjusting the harness to decrease flexion, which usually allows the palsy to resolve completely.

Question 1931

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 35 is diagnosed with a severe left slipped capital femoral epiphysis (SCFE) and undergoes in situ pinning. In which of the following scenarios is prophylactic pinning of the contralateral asymptomatic hip most strongly indicated?

. Male gender
. Age older than 14 years
. Underlying hypothyroidism
. Idiopathic presentation
. Unilateral severe slippage

Correct Answer & Explanation

. Underlying hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended for patients with endocrine disorders (such as hypothyroidism) due to a very high risk of bilateral involvement. Patients who present at an atypically young age (less than 10 years) are also strong candidates for prophylaxis.

Question 1932

Topic: Pediatric Hip

A 12-year-old obese boy presents with a 4-week history of right groin pain and a limp. He denies trauma. During the physical examination of the right hip, what is the most characteristic finding indicating a slipped capital femoral epiphysis (SCFE)?

. Obligatory internal rotation during passive hip flexion
. Obligatory external rotation during passive hip flexion
. Severe pain primarily during hip extension
. A palpable click during passive hip abduction
. Inability to actively extend the knee

Correct Answer & Explanation

. Obligatory external rotation during passive hip flexion

Explanation

The Drehmann sign is the classic physical exam finding in SCFE. As the hip is passively flexed, the thigh obligatorily abducts and externally rotates due to the altered geometry of the proximal femur.

Question 1933

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 report the infant is not kicking the affected leg. Examination reveals decreased active knee extension on that side. This complication is most likely due to which of the following mechanical issues?

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

Correct Answer & Explanation

. Excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion of the hip. Excessive hip abduction, on the other hand, increases the risk of avascular necrosis (AVN) of the femoral head.

Question 1934

Topic: Pediatric Hip

A 6-year-old boy is diagnosed with Legg-Calve-Perthes disease. According to the Herring lateral pillar classification, which of the following radiographic parameters best determines his prognosis and likelihood of developing femoral head deformity?

. The degree of subchondral fracture (Crescent sign)
. The extent of metaphyseal cyst formation
. The height of the lateral pillar of the epiphysis during the fragmentation phase
. The amount of lateral subluxation of the femoral head
. The rate of re-ossification of the medial pillar

Correct Answer & Explanation

. The height of the lateral pillar of the epiphysis during the fragmentation phase

Explanation

The Herring classification focuses on the height of the lateral third (lateral pillar) of the capital femoral epiphysis during the fragmentation phase. A maintained lateral pillar height (>50%) correlates with a more spherical femoral head outcome.

Question 1935

Topic: Pediatric Hip

A 13-year-old boy with a BMI of 32 presents with 4 months of left groin and thigh pain. On physical examination, as his left hip is passively flexed, it obligatorily externally rotates. Which of the following is the most appropriate initial management?

. Closed reduction and spica casting
. In situ single screw fixation
. Open reduction and internal fixation
. Proximal femoral osteotomy
. Observation and crutch use

Correct Answer & Explanation

. In situ single screw fixation

Explanation

The patient has a stable SCFE, indicated by the Drehmann sign. The gold standard treatment for stable SCFE is in situ pinning with a single cannulated screw.

Question 1936

Topic: Pediatric Hip

A 10-year-old girl with previously undiagnosed hypothyroidism presents to the emergency department unable to bear weight on her right leg after a minor fall. Radiographs confirm an acute, unstable slipped capital femoral epiphysis (SCFE). What is the most devastating common complication associated with her diagnosis?

. Chondrolysis
. Avascular necrosis (AVN)
. Femoral neck fracture
. Osteoarthritis
. Nonunion

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

Avascular necrosis is the most severe and relatively common complication of an unstable SCFE, occurring in up to 47% of cases. Urgent decompression and stabilization are debated, but AVN risk remains high.

Question 1937

Topic: Pediatric Hip

Routine prophylactic pinning of the contralateral hip in a patient with a unilateral slipped capital femoral epiphysis (SCFE) is most strongly indicated in which of the following scenarios?

. A 14-year-old boy with a BMI of 25
. A 10-year-old girl with renal osteodystrophy
. A 12-year-old boy with a stable slip
. A 15-year-old girl with an acute unstable slip
. A 13-year-old boy with no medical comorbidities

Correct Answer & Explanation

. A 10-year-old girl with renal osteodystrophy

Explanation

Prophylactic pinning of the asymptomatic contralateral hip is indicated in patients with endocrine disorders (e.g., renal osteodystrophy, hypothyroidism) due to the high risk of bilateral involvement.

Question 1938

Topic: Pediatric Hip

A 12-year-old boy undergoes in situ pinning for a stable slipped capital femoral epiphysis. During the procedure, the surgeon decides on screw placement. Which of the following describes the ideal position of the screw within the epiphysis?

. Anterior and superior
. Anterior and inferior
. Center of the epiphysis
. Posterior and superior
. Posterior and inferior

Correct Answer & Explanation

. Center of the epiphysis

Explanation

The ideal position for a single screw in SCFE fixation is in the center-center of the epiphysis. This provides maximal stability and reduces the risk of joint penetration.

Question 1939

Topic: Pediatric Hip

Which of the following radiographic lines is most useful for diagnosing a subtle slipped capital femoral epiphysis (SCFE) on an AP radiograph of the pelvis?

. Shenton's line
. Hilgenreiner's line
. Perkins' line
. Klein's line
. Ilioischial line

Correct Answer & Explanation

. Klein's line

Explanation

Klein's line is drawn along the superior margin of the femoral neck on an AP view. In a normal hip, it should intersect a portion of the lateral epiphysis; in SCFE, the line passes superior to the epiphysis.

Question 1940

Topic: Pediatric Hip

A 7-year-old boy, whose weight is in the 25th percentile, presents with right knee pain and a limp. Radiographs demonstrate a mild posterior and inferior displacement of the proximal femoral epiphysis. After surgical stabilization, what is the most appropriate next step in management?

. Endocrine workup
. Immediate prophylactic pinning of the contralateral side
. Serial casting
. Non-weight bearing for 6 months
. MRI of the knee

Correct Answer & Explanation

. Endocrine workup

Explanation

SCFE in patients younger than 10 years or older than 16 years, or those with weight below the 50th percentile, warrants an endocrine workup to rule out underlying conditions like hypothyroidism or growth hormone deficiency.

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