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Pediatric Hip MCQs

Practice Set 72 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 1421

Topic: Pediatric Hip

A 12-year-old obese male presents with left knee pain and an antalgic gait. Exam reveals obligatory external rotation of the hip upon passive flexion. Following in situ pinning of a severe slipped capital femoral epiphysis, the patient develops a rapid loss of joint space and progressive stiffness. What is the most likely diagnosis?

. Avascular necrosis
. Chondrolysis
. Septic arthritis
. Femoroacetabular impingement
. Pin penetration into the joint

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a devastating complication of SCFE characterized by rapid loss of articular cartilage and joint stiffness. It is strongly associated with unrecognized intra-articular hardware penetration during pinning.

Question 1422

Topic: Pediatric Hip

A 13-year-old obese male presents with an obligatory external rotation of the hip during active flexion. Radiographs confirm a slipped capital femoral epiphysis (SCFE). This physical exam finding is due to the displacement of the femoral neck in which direction relative to the epiphysis?

. Anterior and superior
. Posterior and inferior
. Anterior and inferior
. Posterior and superior
. Medial and inferior

Correct Answer & Explanation

. Anterior and superior

Explanation

In a SCFE, the epiphysis stays securely in the acetabulum while the femoral neck displaces anteriorly and superiorly. This alters the mechanical axis, causing the thigh to externally rotate during flexion.

Question 1423

Topic: Pediatric Hip

A 6-week-old female treated with a Pavlik harness for developmental dysplasia of the hip lacks active knee extension on the affected side at a 2-week follow-up. This complication is most likely caused by which positioning error?

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

Correct Answer & Explanation

. Excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion of the hips (excessive hip flexion). Treatment involves adjusting the anterior straps to reduce flexion.

Question 1424

Topic: Pediatric Hip

In a 7-year-old boy diagnosed with Legg-Calve-Perthes disease, which of the following classification systems is considered the most reliable radiographic prognostic indicator when assessed at the time of maximal epiphyseal fragmentation?

. Catterall classification
. Salter-Thompson classification
. Lateral pillar classification
. Stulberg classification
. Waldenstrom staging

Correct Answer & Explanation

. Lateral pillar classification

Explanation

The Herring Lateral Pillar classification is the most reliable prognostic indicator for Legg-Calve-Perthes disease. It assesses the height of the lateral third of the epiphysis during the fragmentation phase.

Question 1425

Topic: Pediatric Hip

An infant with developmental dysplasia of the hip (DDH) is treated with a Pavlik harness. During a routine follow-up visit, the infant exhibits decreased spontaneous extension of the knee on the treated side, though hip motion remains unchanged. Which of the following harness positioning errors is most likely responsible for this complication?

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

Correct Answer & Explanation

. Inadequate hip flexion

Explanation

The patient is presenting with a femoral nerve palsy, a known complication of the Pavlik harness resulting from excessive hip flexion. Decreasing the degree of hip flexion usually results in spontaneous recovery of the nerve. Excessive hip abduction is strongly associated with a different, severe complication: avascular necrosis (AVN) of the femoral head.

Question 1426

Topic: Pediatric Hip

A 12-year-old boy presents with a left-sided slipped capital femoral epiphysis (SCFE) and undergoes in situ pinning. Prophylactic pinning of the contralateral, asymptomatic hip is most strongly indicated if the patient has which of the following concurrent conditions?

. Asthma
. Type 1 Diabetes Mellitus
. Hypothyroidism
. Marfan syndrome
. Sickle cell trait

Correct Answer & Explanation

. Hypothyroidism

Explanation

Endocrine disorders (such as hypothyroidism, panhypopituitarism, or growth hormone deficiency) and renal osteodystrophy significantly increase the risk for bilateral SCFE. In these atypical SCFE patients, prophylactic pinning of the contralateral hip is strongly indicated to prevent future slippage.

Question 1427

Topic: Pediatric Hip

A 6-week-old female infant is undergoing treatment with a Pavlik harness for developmental dysplasia of the hip (DDH). A follow-up ultrasound reveals the femoral head remains dislocated posterosuperiorly and is irreducible on dynamic testing. Continued rigid use of the Pavlik harness in this situation places the patient at highest risk for which of the following complications?

. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Erosion of the posterior acetabulum (Pavlik disease)
. Inferior dislocation of the hip
. Premature triradiate cartilage closure

Correct Answer & Explanation

. Erosion of the posterior acetabulum (Pavlik disease)

Explanation

If a hip remains persistently dislocated in a Pavlik harness, continued use can cause the femoral head to wear away the posterior lip of the acetabulum, known as 'Pavlik harness disease.' It creates a false acetabulum and makes subsequent reduction significantly more difficult. Therefore, if reduction is not achieved within 3 to 4 weeks, the harness should be abandoned. Avascular necrosis is associated with extreme abduction, and femoral nerve palsy is associated with extreme hyperflexion.

Question 1428

Topic: Pediatric Hip

In the evaluation of a 7-year-old boy with Legg-Calve-Perthes disease, the lateral pillar (Herring) classification is utilized to determine prognosis. This classification is primarily based on the height of the lateral pillar of the capital femoral epiphysis during which stage of the disease?

. Initial (avascular) stage
. Fragmentation stage
. Reossification stage
. Healed stage
. Prodromal stage

Correct Answer & Explanation

. Fragmentation stage

Explanation

The lateral pillar (Herring) classification relies on anteroposterior radiographs specifically taken during the fragmentation stage of Legg-Calve-Perthes disease. It assesses the maintenance of the height of the lateral pillar of the femoral head, which correlates strongly with long-term sphericity, containment, and clinical outcome.

Question 1429

Topic: Pediatric Hip

In the assessment of Legg-Calve-Perthes disease, the Lateral Pillar (Herring) classification is widely used for determining prognosis. What specific radiographic feature defines a Lateral Pillar Group B hip on an AP radiograph?

. No involvement or radiolucency of the lateral pillar
. Greater than 50% maintenance of the lateral pillar height
. Less than 50% maintenance of the lateral pillar height
. Extrusion of the femoral head laterally beyond the acetabulum
. Complete collapse and fragmentation of the entire epiphysis

Correct Answer & Explanation

. Greater than 50% maintenance of the lateral pillar height

Explanation

In the Herring Lateral Pillar classification, Group B indicates that the lateral pillar maintains >50% of its original height, yielding an intermediate prognosis. Group A has no lateral pillar height loss, while Group C has <50% height maintained, signifying a poor prognosis.

Question 1430

Topic: Pediatric Hip

A 12-year-old obese boy presents with knee pain and an obligatory external rotation of the hip during active flexion. Radiographs confirm a slipped capital femoral epiphysis (SCFE). What is the primary reason for performing an in situ single-screw fixation rather than attempting closed reduction?

. To prevent chondrolysis
. To decrease the risk of avascular necrosis
. To prevent premature physeal closure
. To avoid prominent hardware
. To allow for future remodeling

Correct Answer & Explanation

. To decrease the risk of avascular necrosis

Explanation

Forceful closed reduction of a SCFE significantly increases the risk of avascular necrosis of the femoral head. This complication occurs due to stretching or tearing of the delicate retinacular vessels supplying the epiphysis.

Question 1431

Topic: Pediatric Hip

A 6-year-old boy is diagnosed with Legg-Calve-Perthes disease. According to the Herring lateral pillar classification, which radiographic finding portends the poorest prognosis for future hip joint congruency?

. Less than 50% loss of lateral pillar height
. Greater than 50% loss of lateral pillar height
. Involvement of the medial pillar only
. Central pillar fragmentation with intact lateral pillar
. Epiphyseal extrusion without lateral pillar collapse

Correct Answer & Explanation

. Greater than 50% loss of lateral pillar height

Explanation

The Herring lateral pillar classification determines prognosis based on the height of the lateral aspect of the femoral epiphysis. Group C, characterized by greater than 50% loss of lateral pillar height, carries the worst prognosis for maintaining femoral head sphericity.

Question 1432

Topic: Pediatric Hip

A 13-year-old obese male presents with acute-on-chronic left hip pain and an inability to bear weight. Radiographs show a severe slipped capital femoral epiphysis (SCFE). He undergoes urgent in-situ pinning. What is the most common devastating complication associated with this specific presentation?

. Chondrolysis
. Osteonecrosis (avascular necrosis) of the femoral head
. Femoroacetabular impingement
. Premature physeal closure
. Subtrochanteric femur fracture

Correct Answer & Explanation

. Osteonecrosis (avascular necrosis) of the femoral head

Explanation

Unstable SCFE (defined clinically by the inability to bear weight) carries a high risk of osteonecrosis of the femoral head, regardless of the treatment method. The risk can approach 50% in severe, unstable slips.

Question 1433

Topic: Pediatric Hip

A 6-year-old boy is diagnosed with Legg-Calve-Perthes disease. According to the Herring lateral pillar classification, a patient with greater than 50% loss of lateral pillar height is placed in which prognostic group?

. Group A
. Group B
. Group B/C border
. Group C
. Group D

Correct Answer & Explanation

. Group C

Explanation

The Herring lateral pillar classification categorizes Perthes based on the height of the lateral pillar on the AP radiograph. Group C is defined by a loss of more than 50% of the lateral pillar height and is associated with a poor prognosis and high risk of aspherical healing.

Question 1434

Topic: Pediatric Hip

When performing a total hip arthroplasty on a patient with Crowe Type IV developmental dysplasia of the hip (DDH), which of the following surgical strategies is most often required to safely bring the hip center down to the true acetabulum without causing sciatic nerve palsy?

. Extensive sequential soft tissue releases alone
. Placing the acetabular cup in a high hip center
. A distal femoral shortening osteotomy
. A subtrochanteric shortening osteotomy
. A structural bulk allograft on the superior acetabular rim

Correct Answer & Explanation

. A subtrochanteric shortening osteotomy

Explanation

In Crowe Type IV DDH (high dislocation), pulling the femur down to the true (anatomic) acetabulum places massive stretch on the sciatic nerve. A subtrochanteric shortening osteotomy is standard to safely reduce the hip without causing an irreversible stretch injury to the nerve.

Question 1435

Topic: Pediatric Hip

A 55-year-old male is scheduled for a total hip arthroplasty. He has a history of severe developmental dysplasia of the hip (Crowe Type IV). You plan a subtrochanteric shortening osteotomy. Which of the following is the most critical advantage of this technique compared to a greater trochanteric slide osteotomy?

. Preserves the abductor mechanism insertion
. Avoids the need for custom femoral components
. Allows correction of excessive femoral anteversion
. Prevents sciatic nerve palsy by shortening the femur
. Eliminates the risk of nonunion

Correct Answer & Explanation

. Preserves the abductor mechanism insertion

Explanation

In Crowe IV DDH, bringing the femoral head distally into the true acetabulum stretches the sciatic nerve. A subtrochanteric shortening osteotomy critically reduces this tension, significantly lowering the risk of sciatic nerve palsy.

Question 1436

Topic: Pediatric Hip

An infant is being treated for Developmental Dysplasia of the Hip (DDH) using a Pavlik harness. During a follow-up visit, the infant is noted to have decreased active knee extension on the treated side. This complication is most commonly associated with which of the following positioning errors?

. Excessive flexion of the hips
. Excessive abduction of the hips
. Inadequate flexion of the hips
. Inadequate abduction of the hips
. Excessive internal rotation of the hips

Correct Answer & Explanation

. Excessive flexion of the hips

Explanation

In a Pavlik harness, excessive flexion of the hips (>120 degrees) can compress the femoral nerve against the inguinal ligament, leading to a transient femoral nerve palsy (manifesting as decreased active quadriceps extension). Conversely, excessive hyperabduction is associated with avascular necrosis (AVN) of the femoral head.

Question 1437

Topic: Pediatric Hip

A 9-year-old boy presents with an insidious onset of a limp, thigh pain, and obligatory external rotation of the hip with flexion. He is noted to be significantly shorter than his peers, plotting below the 5th percentile for height. Radiographs confirm a bilateral Slipped Capital Femoral Epiphysis (SCFE). Given his age and presentation, which of the following underlying systemic conditions must be highly suspected?

. Hypothyroidism
. Hyperthyroidism
. Hyperparathyroidism
. Addison's disease
. Type 1 Diabetes mellitus

Correct Answer & Explanation

. Hypothyroidism

Explanation

SCFE typically occurs during the adolescent growth spurt (males 12-16 years, females 10-14 years). When it presents in a patient outside this typical age range (e.g., <10 years), with bilateral involvement, or in a patient with short stature, an underlying endocrine abnormality should be strongly suspected, with hypothyroidism being the most common association.

Question 1438

Topic: Pediatric Hip

Slipped capital femoral epiphysis (SCFE) typically occurs in overweight adolescents undergoing a rapid growth spurt. Which of the following patient profiles should prompt an immediate and thorough laboratory workup for an underlying endocrine or renal abnormality?

. A 13-year-old male with a BMI in the 95th percentile
. A 12-year-old female presenting with acute-on-chronic bilateral knee pain
. A 9-year-old male with a BMI in the 30th percentile
. A 14-year-old male with a history of a prior contralateral SCFE
. A 15-year-old African American male with left hip pain

Correct Answer & Explanation

. A 13-year-old male with a BMI in the 95th percentile

Explanation

Atypical SCFE presentations that warrant an endocrine workup (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency) include age of onset less than 10 years or greater than 16 years, and weight less than the 50th percentile.

Question 1439

Topic: Pediatric Hip

A 12-year-old obese male presents with a left Slipped Capital Femoral Epiphysis (SCFE). Which of the following factors is considered the strongest indication for prophylactic in situ pinning of the asymptomatic contralateral hip?

. Male gender
. Age greater than 14 years
. Concurrent underlying endocrine disorder
. Body mass index > 95th percentile
. Family history of SCFE

Correct Answer & Explanation

. Male gender

Explanation

Patients with an underlying endocrine disorder (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) have a significantly higher risk of bilateral SCFE. Prophylactic pinning of the contralateral side is strongly recommended in these individuals.

Question 1440

Topic: Pediatric Hip

In a 12-year-old male presenting with a unilateral slipped capital femoral epiphysis (SCFE), which of the following factors is the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Male sex
. BMI greater than 35
. Presentation with isolated knee pain instead of hip pain
. Presence of an endocrine disorder such as hypothyroidism
. Symptomatic slip angle greater than 50 degrees

Correct Answer & Explanation

. Male sex

Explanation

Endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) significantly increase the risk of bilateral SCFE. Prophylactic pinning of the contralateral hip is highly recommended in these patients to prevent a secondary slip.

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