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Pediatric Hip MCQs

Practice Set 6 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 101

Topic: Pediatric Hip

A 6-month-old boy with Developmental Dysplasia of the Hip (DDH) has failed Pavlik harness treatment. A closed reduction and spica casting are planned. To minimize the risk of osteonecrosis of the femoral head, what defines the "safe zone" of positioning described by Ramsey?

. Between maximum adduction and the angle of re-dislocation
. Between maximum abduction and the angle of re-dislocation
. Between 90 degrees of flexion and maximum extension
. Between internal and external rotation limits
. Strict immobilization in the rigid Lorenz position

Correct Answer & Explanation

. Between maximum abduction and the angle of re-dislocation

Explanation

Ramsey's safe zone for DDH closed reduction is the arc between the angle of maximum abduction (which risks AVN if pushed too far) and the angle at which the hip redislocates in adduction. Spica casting should immobilize the hip within this safe arc.

Question 102

Topic: Pediatric Hip

In Legg-Calve-Perthes disease, the lateral pillar classification is used to determine prognosis. At what stage of the disease is this classification most accurately applied to guide treatment?

. Initial condensation stage
. Early fragmentation stage
. Late fragmentation stage
. Early reossification stage
. Healed stage

Correct Answer & Explanation

. Early fragmentation stage

Explanation

The lateral pillar (Herring) classification determines the retained height of the lateral pillar of the femoral head. It is most accurate and prognostically valuable when assessed during the early to late fragmentation phase of the disease.

Question 103

Topic: Pediatric Hip

A 14-year-old boy with a BMI of 35 presents with knee pain and is diagnosed with a unilateral slipped capital femoral epiphysis (SCFE). Which of the following best describes the anatomical direction of the epiphyseal slip relative to the femoral neck?

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

Correct Answer & Explanation

. Posterior and inferior

Explanation

In SCFE, the femoral neck typically displaces anteriorly and superiorly. This means the epiphysis, which stays relatively reduced in the acetabulum, slips posteriorly and inferiorly relative to the femoral neck.

Question 104

Topic: Pediatric Hip
A 12-year-old overweight boy presents with sudden onset of severe groin pain and inability to bear weight on his right leg after a minor fall. Radiographs demonstrate a displaced capital femoral epiphysis. He had 3 weeks of mild antecedent thigh aching. Which of the following best characterizes his condition and associated risk?
. Stable SCFE with low risk of avascular necrosis
. Unstable SCFE with high risk of avascular necrosis
. Stable SCFE with high risk of chondrolysis
. Unstable SCFE with low risk of avascular necrosis
. Legg-Calvé-Perthes disease with high risk of coxa magna

Correct Answer & Explanation

. Unstable SCFE with high risk of avascular necrosis

Explanation

The inability to bear weight makes this an unstable slipped capital femoral epiphysis (SCFE) according to the Loder classification. Unstable SCFE has a significantly higher risk of avascular necrosis (AVN), historically up to 47%, compared to stable SCFE.

Question 105

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease. According to the Herring lateral pillar classification, which radiographic finding defines a Group C hip?
. No lucency in the lateral pillar
. Greater than 50% of lateral pillar height maintained
. Less than 50% of lateral pillar height maintained
. Complete resorption of the medial pillar
. Subchondral fracture extending into the lateral pillar

Correct Answer & Explanation

. Less than 50% of lateral pillar height maintained

Explanation

In the Herring lateral pillar classification, Group C is defined by the maintenance of less than 50% of the original lateral pillar height. This group carries the poorest prognosis for subsequent hip deformity and osteoarthritis.

Question 106

Topic: Pediatric Hip
A 6-year-old child presents with a painless limp. Examination reveals limited abduction and internal rotation of the hip. Radiographs show increased radiodensity and fragmentation of the capital femoral epiphysis. What is the primary goal of treatment for this condition?
. Immediate fusion of the hip joint
. Containment of the femoral head within the acetabulum
. Prophylactic pinning of the contralateral hip
. Eradication of infection with antibiotics
. Surgical excision of the fragmented epiphysis

Correct Answer & Explanation

. Containment of the femoral head within the acetabulum

Explanation

The diagnosis is Legg-Calvé-Perthes disease. The primary goal of treatment is containment of the femoral head within the acetabulum during the fragmentation and reossification phases to ensure it heals spherically and to prevent late osteoarthritis.

Question 107

Topic: Pediatric Hip

A 12-year-old obese boy presents to the emergency department unable to bear weight on his right leg after a minor fall. Radiographs demonstrate a severe right slipped capital femoral epiphysis (SCFE). Which of the following complications is he at the highest risk for developing compared to a patient who can bear weight?

. Chondrolysis
. Avascular necrosis (AVN)
. Femoroacetabular impingement (FAI)
. Premature osteoarthritis
. Leg length discrepancy

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

The inability to bear weight defines an unstable SCFE, which carries a significantly higher risk of avascular necrosis (up to 50%) compared to a stable SCFE. Urgent or semi-urgent in-situ pinning is required.

Question 108

Topic: Pediatric Hip

In patients presenting with a unilateral slipped capital femoral epiphysis (SCFE), which of the following is the strongest indication for prophylactic pinning of the contralateral hip?

. Age greater than 14 years in males
. Presentation with an unstable slip
. Presence of endocrine or metabolic disorders
. High body mass index (>95th percentile) alone
. Severity of the initial slip angle (>50 degrees)

Correct Answer & Explanation

. Presence of endocrine or metabolic disorders

Explanation

Patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) or undergoing radiation therapy have a very high risk of bilateral SCFE. Prophylactic pinning of the contralateral hip is strongly recommended in these populations regardless of age.

Question 109

Topic: Pediatric Hip

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). What is the risk of excessive hyperflexion of the hips while in the harness?

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

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Excessive hyperflexion (>120 degrees) in a Pavlik harness risks femoral nerve palsy. Excessive abduction increases the risk of avascular necrosis of the femoral head.

Question 110

Topic: Pediatric Hip

In evaluating a 7-year-old child with Legg-Calve-Perthes disease, the Herring Lateral Pillar Classification is used to determine prognosis. Which radiographic view and stage of the disease are most appropriate for applying this classification?

. Frog-leg lateral view during the initial stage
. Anteroposterior (AP) pelvis during the fragmentation stage
. Frog-leg lateral view during the reossification stage
. Anteroposterior (AP) pelvis during the initial stage
. Dunn view during the fragmentation stage

Correct Answer & Explanation

. Anteroposterior (AP) pelvis during the fragmentation stage

Explanation

The Herring Lateral Pillar Classification assesses the height of the lateral pillar of the femoral head and is best applied on an AP radiograph during the fragmentation stage of the disease. This stage provides the most accurate prognostic information regarding final femoral head sphericity.

Question 111

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, you notice the infant has decreased active knee extension on the affected side. Which of the following is the most appropriate next step?

. Immediate open reduction
. Switching to a spica cast
. Adjusting the harness to decrease hip flexion
. Obtaining an MRI of the lumbar spine
. Performing an ultrasound of the hip

Correct Answer & Explanation

. Adjusting the harness to decrease hip flexion

Explanation

Decreased active knee extension indicates a femoral nerve palsy, a known complication of excessive hyperflexion in a Pavlik harness. The harness should be discontinued or adjusted to decrease hip flexion. Observation is typically sufficient as it generally resolves spontaneously.

Question 112

Topic: Pediatric Hip

A 12-year-old obese boy presents with acute-on-chronic left groin pain and inability to bear weight. Radiographs show a severe slipped capital femoral epiphysis (SCFE). Which of the following factors most significantly increases his risk of avascular necrosis (AVN)?

. Degree of posterior slip angle > 50 degrees
. Age of the patient > 14 years
. Bilateral involvement
. Inability to bear weight on the affected limb
. Concomitant endocrine abnormalities

Correct Answer & Explanation

. Inability to bear weight on the affected limb

Explanation

The inability to bear weight defines an unstable SCFE, which carries a much higher risk of avascular necrosis (up to 50%) compared to a stable SCFE. Severity of the slip is less predictive of AVN than the stability of the physis.

Question 113

Topic: Pediatric Hip

In the evaluation of a 6-year-old boy with Legg-Calve-Perthes disease, which of the following radiographic classifications is most prognostic for long-term hip joint congruency?

. Catterall classification
. Lateral pillar (Herring) classification
. Salter-Thompson classification
. Stulberg classification
. Reimer's migration index

Correct Answer & Explanation

. Lateral pillar (Herring) classification

Explanation

The lateral pillar (Herring) classification is considered the most reliable prognostic indicator for long-term outcomes in Perthes disease. It assesses the height of the lateral pillar of the capital femoral epiphysis during the fragmentation phase. The Stulberg classification assesses the final outcome at skeletal maturity, not initial prognosis.

Question 114

Topic: Pediatric Hip

A 12-year-old obese boy presents with an acute exacerbation of chronic right groin pain and an inability to bear weight. Radiographs show a severe slipped capital femoral epiphysis (SCFE). Which of the following intraoperative maneuvers is most strongly associated with the development of avascular necrosis (AVN)?

. Using a single cannulated screw for fixation
. Forceful closed reduction to restore anatomic alignment
. In situ pinning without reduction
. Capsulotomy for hematoma decompression
. Using a smooth wire instead of a threaded screw

Correct Answer & Explanation

. Forceful closed reduction to restore anatomic alignment

Explanation

Forceful closed reduction of a SCFE compromises the delicate retinacular vessels, significantly increasing the risk of avascular necrosis. Current gold-standard management involves gentle positioning and in situ pinning.

Question 115

Topic: Pediatric Hip
In Legg-Calvé-Perthes disease, the Herring lateral pillar classification is used to predict long-term outcomes. During which phase of the disease should the radiographs be evaluated to determine the lateral pillar grade?
. Initial phase
. Early fragmentation phase
. Late fragmentation phase
. Reossification phase
. Healed phase

Correct Answer & Explanation

. Late fragmentation phase

Explanation

The Herring lateral pillar classification is most accurately determined during the late fragmentation phase of Legg-Calvé-Perthes disease. This ensures the maximal extent of epiphyseal involvement is visible for prognostic accuracy.

Question 116

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). The mother notes that the child has stopped actively extending the knee on the treated side. Which of the following harness positioning errors most likely caused this complication?

. Excessive hip flexion
. Excessive hip extension
. Excessive hip abduction
. Excessive hip adduction
. Excessive knee flexion

Correct Answer & Explanation

. Excessive hip flexion

Explanation

Excessive hip flexion in a Pavlik harness (typically >120 degrees) can cause femoral nerve compression against the inguinal ligament, leading to quadriceps palsy and an inability to extend the knee. Excessive abduction leads to AVN.

Question 117

Topic: Pediatric Hip

A 13-year-old boy presents with left hip pain and an antalgic gait. During physical examination, as the affected hip is passively flexed, the thigh obligatorily rotates externally. This clinical finding is known as:

. Galeazzi sign
. Drehmann sign
. Ortolani test
. Barlow maneuver
. Trendelenburg sign

Correct Answer & Explanation

. Drehmann sign

Explanation

The Drehmann sign describes the obligatory external rotation and abduction of the hip during passive flexion. It is a classic physical examination finding in slipped capital femoral epiphysis (SCFE).

Question 118

Topic: Pediatric Hip
A 14-year-old girl is kicking a soccer ball when she feels a "pop" in her hip. The most likely diagnosis is:
. Slipped sacroiliac joint
. Slipped capital femoral epiphysis
. Pathologic hip fracture
. Avulsion of the anterior inferior iliac spine
. Ligamentum teres avulsion

Correct Answer & Explanation

. Avulsion of the anterior inferior iliac spine

Explanation

This is a classic description of avulsion of the anterior inferior iliac spine. When this patient hyperextended her hip and flexed her knee simultaneously to kick a ball, the rectus femoris was stretched at both joints. In a skeletally immature patient, this apophysis is not fully ossified and is vulnerable to avulsion. Treatment is symptomatic, with return to sports in about 6 weeks.

Question 119

Topic: Pediatric Hip

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

. A 14-year-old male with an acute, unstable SCFE
. A 10-year-old female with an endocrine disorder
. A 15-year-old male with a chronic, stable SCFE
. A 13-year-old male with a BMI in the 85th percentile
. A 12-year-old female with an isolated slipped epiphysis and normal thyroid function

Correct Answer & Explanation

. A 10-year-old female with an endocrine disorder

Explanation

Prophylactic pinning of the contralateral hip is highly recommended for patients with SCFE who have underlying endocrine disorders (e.g., hypothyroidism) or are younger than 10 years old, due to a significantly elevated risk of bilateral involvement.

Question 120

Topic: Pediatric Hip

On an infant hip ultrasound used to evaluate developmental dysplasia of the hip (DDH), the alpha angle is defined by the intersection of the baseline (iliac wing) and which other structure?

. The bony roof of the acetabulum
. The cartilaginous roof (labrum)
. The femoral head center
. The triradiate cartilage
. The joint capsule

Correct Answer & Explanation

. The bony roof of the acetabulum

Explanation

The alpha angle measures the bony roof of the acetabulum and is formed by the intersection of the baseline (parallel to the iliac wing) and the bony roof line. An alpha angle greater than 60 degrees is considered normal.

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