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Pediatric Hip MCQs

Practice Set 7 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 121

Topic: Pediatric Hip

According to the Herring lateral pillar classification for Legg-Calve-Perthes disease, a patient in Group C has what characteristic radiographic finding?

. No involvement of the lateral pillar
. >50% of the lateral pillar height maintained
. <50% of the lateral pillar height maintained
. Complete collapse of the central pillar only
. Extrusion of the femoral head beyond the acetabulum

Correct Answer & Explanation

. <50% of the lateral pillar height maintained

Explanation

In the Herring lateral pillar classification, Group C is characterized by the maintenance of less than 50% of the normal lateral pillar height. This group has the poorest prognosis and highest risk of secondary osteoarthritis.

Question 122

Topic: Pediatric Hip

While treating a 6-week-old infant with developmental dysplasia of the hip (DDH) using a Pavlik harness, you note the infant lacks active knee extension on the treated side. What is the most likely cause?

. Avascular necrosis of the femoral head
. Excessive hip abduction in the harness
. Excessive hip flexion in the harness
. Development of a septic hip
. Normal physiologic variant at this age

Correct Answer & Explanation

. Excessive hip flexion in the harness

Explanation

Excessive hip flexion in a Pavlik harness can lead to compression of the femoral nerve against the rim of the pelvis, causing a transient femoral nerve palsy. Excessive abduction, on the other hand, is classically associated with avascular necrosis.

Question 123

Topic: Pediatric Hip

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

. A 14-year-old male with a BMI of 30
. A 10-year-old female with hypothyroidism
. An 11-year-old male with a history of minor trauma
. A 13-year-old female with an acute-on-chronic slip
. A 15-year-old male with a stable slip

Correct Answer & Explanation

. A 10-year-old female with hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is recommended for patients with underlying endocrine or metabolic disorders (like hypothyroidism or renal osteodystrophy) due to the very high risk of bilateral involvement.

Question 124

Topic: Pediatric Hip

In Legg-Calve-Perthes disease, the Herring Lateral Pillar classification is used to determine prognosis. At what stage of the disease is this classification most accurately applied?

. Initial phase
. Fragmentation phase
. Reossification phase
. Healed phase
. Prior to symptom onset

Correct Answer & Explanation

. Fragmentation phase

Explanation

The Herring Lateral Pillar classification evaluates the height of the lateral third of the capital femoral epiphysis on an AP radiograph. It is most accurately and reliably applied during the early fragmentation phase.

Question 125

Topic: Pediatric Hip

A 13-year-old obese male presents with an unstable slipped capital femoral epiphysis (SCFE). Following in situ pinning, he develops severe, progressive restriction of hip motion without signs of infection. Radiographs show joint space narrowing. What is the most likely diagnosis?

. Avascular necrosis
. Chondrolysis
. Septic arthritis
. Implant failure
. Femoroacetabular impingement

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis involves rapid, progressive destruction of the articular cartilage. It is a known complication of SCFE, particularly associated with unrecognized intra-articular pin penetration, presenting with painful restriction of motion.

Question 126

Topic: Pediatric Hip

In a 12-year-old boy presenting with a unilateral slipped capital femoral epiphysis (SCFE), prophylactic pinning of the contralateral asymptomatic hip is most strongly indicated if the patient has which of the following concomitant conditions?

. Body mass index greater than the 95th percentile
. Hypothyroidism
. Male gender
. African American descent
. Retroverted acetabulum

Correct Answer & Explanation

. Hypothyroidism

Explanation

Endocrine disorders, such as hypothyroidism or renal osteodystrophy, significantly increase the risk of bilateral SCFE. Prophylactic pinning of the contralateral hip is strongly recommended in these atypical or syndromic cases.

Question 127

Topic: Pediatric Hip

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

. A 14-year-old boy with a BMI of 30
. A 10-year-old girl with primary hypothyroidism
. A 13-year-old boy with a Southwick slip angle of 30 degrees
. A 12-year-old girl with an acute-on-chronic slip
. A 15-year-old boy with closed triradiate cartilages

Correct Answer & Explanation

. A 10-year-old girl with primary hypothyroidism

Explanation

Prophylactic contralateral pinning is highly recommended for patients with an endocrine disorder (like hypothyroidism or renal osteodystrophy) or those who are very young (<10 years), due to the high risk of contralateral slip.

Question 128

Topic: Pediatric Hip

According to the Herring Lateral Pillar classification for Legg-Calve-Perthes disease, which of the following radiographic findings defines a Group C hip?

. No involvement of the lateral pillar
. Greater than 50% of lateral pillar height maintained
. Less than 50% of lateral pillar height maintained
. Extensive metaphyseal cysts
. Presence of a subchondral crescent sign

Correct Answer & Explanation

. Less than 50% of lateral pillar height maintained

Explanation

The Herring classification assesses the height of the lateral pillar on the AP pelvis radiograph during the fragmentation stage. Group C is defined by the lateral pillar maintaining less than 50% of its original height, indicating a poor prognosis.

Question 129

Topic: Pediatric Hip

A 3-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the follow-up visit, the infant exhibits an absence of active knee extension. Which of the following is the most appropriate next step in management?

. Perform a closed reduction and spica casting
. Adjust the harness to increase hip flexion
. Discontinue the Pavlik harness immediately
. Add a hip abduction brace
. Continue current treatment as this is a transient normal finding

Correct Answer & Explanation

. Discontinue the Pavlik harness immediately

Explanation

Absence of active knee extension indicates a femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness. The harness must be discontinued or significantly adjusted immediately to prevent permanent damage.

Question 130

Topic: Pediatric Hip

A 13-year-old obese boy presents with a 3-week history of vaguely localized knee pain and a limp. Examination reveals obligatory external rotation of the hip during passive hip flexion. What is the most appropriate initial management?

. Open reduction and internal fixation
. Closed reduction and internal fixation
. In situ single screw fixation
. Spica cast application
. Proximal femoral osteotomy

Correct Answer & Explanation

. In situ single screw fixation

Explanation

The presentation is classic for a slipped capital femoral epiphysis (SCFE), characterized by obligatory external rotation with hip flexion. The gold standard initial treatment for a stable SCFE is in situ fixation with a single cannulated screw.

Question 131

Topic: Pediatric Hip
A 6-year-old boy with a painless limp is diagnosed with Legg-Calvé-Perthes disease. Radiographs show fragmentation of the femoral head. According to the Herring lateral pillar classification, a Group C classification is defined by what degree of lateral pillar height loss?
. No height loss
. <25% height loss
. 25-50% height loss
. >50% height loss
. Complete head collapse

Correct Answer & Explanation

. >50% height loss

Explanation

The Herring lateral pillar classification determines prognosis in Legg-Calvé-Perthes disease based on the height of the lateral pillar during the fragmentation stage. Group C indicates greater than 50% loss of lateral pillar height and carries the poorest prognosis.

Question 132

Topic: Pediatric Hip

A 3-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During follow-up, the parents note the infant is no longer actively extending the knee on the affected side. What is the most appropriate next step in management?

. Continue the harness and observe
. Adjust the anterior straps to increase flexion
. Remove the harness and allow temporary rest
. Switch to a rigid abduction brace immediately
. Perform closed reduction and spica casting

Correct Answer & Explanation

. Remove the harness and allow temporary rest

Explanation

Decreased active knee extension in a Pavlik harness indicates a femoral nerve palsy, typically caused by hyperflexion. The correct management is immediate removal of the harness to allow for nerve recovery before reassessing treatment options.

Question 133

Topic: Pediatric Hip

A 12-year-old obese boy presents with right thigh pain and a limp for 3 weeks. Examination reveals obligatory external rotation of the right hip during passive flexion. Radiographs demonstrate a 'slip' of the capital femoral epiphysis. What is the most appropriate initial treatment?

. Closed reduction and spica casting
. In situ single screw fixation
. Capital realignment osteotomy
. Slipped capital femoral epiphysis pinning with two screws
. Observation and protected weight bearing

Correct Answer & Explanation

. In situ single screw fixation

Explanation

The patient has a stable slipped capital femoral epiphysis (SCFE). The standard of care is in situ fixation with a single cannulated screw placed in the center of the epiphysis.

Question 134

Topic: Pediatric Hip

A 3-month-old girl is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up visit, the parents report she has stopped kicking her left leg, and you note an absence of active knee extension. What is the most appropriate next step in management?

. Switch to a rigid hip abduction orthosis
. Adjust the anterior straps to increase hip flexion
. Remove the harness and allow a period of rest
. Perform an urgent ultrasound of the hip
. Reassure the parents and continue the current harness settings

Correct Answer & Explanation

. Remove the harness and allow a period of rest

Explanation

Decreased active knee extension in a Pavlik harness indicates a femoral nerve palsy caused by hyperflexion of the hip. The harness must be removed or adjusted immediately to allow recovery of nerve function.

Question 135

Topic: Pediatric Hip

A 5-year-old boy presents with a limp and hip pain. Radiographs demonstrate sclerosis and fragmentation of the proximal femoral epiphysis. Which radiographic sign is considered a 'head-at-risk' sign in Legg-Calve-Perthes disease?

. Crescent sign
. Gage sign
. Klein's line disruption
. Waldenstrom sign
. Trethowan sign

Correct Answer & Explanation

. Gage sign

Explanation

The Gage sign (a V-shaped radiolucency in the lateral portion of the epiphysis and adjacent metaphysis) is a classic 'head-at-risk' sign indicating potential for poor outcomes in Perthes disease.

Question 136

Topic: Pediatric Hip

A 13-year-old obese male presents with acute worsening of chronic left hip pain. On examination, he has an obligatory external rotation of the hip during passive flexion. Radiographs demonstrate a severe, unstable slipped capital femoral epiphysis (SCFE). What is the most severe and frequent complication specifically associated with an unstable SCFE?

. Chondrolysis
. Avascular necrosis of the femoral head
. Femoroacetabular impingement
. Leg length discrepancy
. Slipped progression

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Unstable SCFE carries a significantly higher risk of avascular necrosis (AVN) of the femoral head, with rates up to 50%. Chondrolysis is more commonly associated with prominent hardware following in situ pinning.

Question 137

Topic: Pediatric Hip

A 3-month-old female is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. Her parents report that she is no longer actively extending her knee on the treated side. Which of the following nerve palsies is most likely occurring?

. Sciatic nerve palsy
. Obturator nerve palsy
. Femoral nerve palsy
. Common peroneal nerve palsy
. Superior gluteal nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, typically occurring when the hip is in hyperflexion. The harness should be adjusted or discontinued until active quadriceps function returns.

Question 138

Topic: Pediatric Hip

In a 6-year-old boy diagnosed with Legg-Calve-Perthes disease, the Herring lateral pillar classification is used to determine prognosis. A Type B classification indicates that what percentage of the lateral pillar height is maintained on the anteroposterior radiograph?

. Less than 25%
. Between 25% and 50%
. Greater than 50%
. Exactly 100%
. 0%

Correct Answer & Explanation

. Greater than 50%

Explanation

According to the Herring classification, Type B is defined by the maintenance of >50% of the lateral pillar height. Type C indicates <50% height maintenance, portending a worse prognosis.

Question 139

Topic: Pediatric Hip

A 13-year-old obese male undergoes in situ pinning for a stable slipped capital femoral epiphysis (SCFE). Six months postoperatively, he presents with severe hip stiffness, pain, and a 50% reduction in joint space on radiographs. No signs of infection are present. What is the most likely diagnosis?

. Avascular necrosis
. Chondrolysis
. Implant failure
. Femoroacetabular impingement
. Septic arthritis

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a known complication of SCFE, characterized by acute cartilage destruction, joint space narrowing to less than 3 mm, and severe stiffness. It can occur secondary to unrecognized pin penetration into the joint or intrinsically from the disease process.

Question 140

Topic: Pediatric Hip
In evaluating a 9-year-old boy with Legg-Calvé-Perthes disease, which of the following is the most significant prognostic factor for long-term hip deformity?
. Degree of medial subluxation
. Age at the onset of symptoms
. Presence of a Gage sign
. Metaphyseal cysts
. Extent of anterior epiphyseal involvement

Correct Answer & Explanation

. Age at the onset of symptoms

Explanation

The two most critical prognostic factors in Legg-Calvé-Perthes disease are the age of onset (worse prognosis if older than 8 years) and the lateral pillar classification (extent of lateral epiphyseal involvement). Older children have less time for spherical remodeling before skeletal maturity.

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