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Pediatric Hip MCQs

Practice Set 87 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 1721

Topic: Pediatric Hip

A 13-year-old obese male presents with a stable slipped capital femoral epiphysis (SCFE) of the left hip. Prophylactic pinning of the contralateral, asymptomatic hip is most strongly recommended for patients with which of the following underlying conditions?

. Obesity greater than the 99th percentile
. Type 2 diabetes mellitus
. Endocrine disorders (e.g., hypothyroidism or panhypopituitarism)
. Previous history of significant hip trauma
. Nutritional Vitamin D deficiency

Correct Answer & Explanation

. Endocrine disorders (e.g., hypothyroidism or panhypopituitarism)

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial for typical patients but is highly recommended in patients with an underlying endocrinopathy (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency), as their risk for a contralateral slip approaches 50-100%.

Question 1722

Topic: Pediatric Hip

A 3-month-old infant is being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). At follow-up, the parents report the infant is not kicking the affected leg. Physical exam reveals absent active knee extension, but active ankle dorsiflexion is intact. Which complication of the harness has most likely occurred?

. Obturator nerve palsy
. Sciatic nerve palsy
. Femoral nerve palsy
. Avascular necrosis of the femoral head
. Superior gluteal nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion of the hips in a Pavlik harness can compress the femoral nerve against the rim of the pelvis or inguinal ligament, leading to a femoral nerve palsy. This manifests clinically as an inability to actively extend the knee. The treatment is temporary discontinuation or adjustment of the harness.

Question 1723

Topic: Pediatric Hip

A 4-week-old female infant is diagnosed with developmental dysplasia of the hip (DDH) and placed in a Pavlik harness. While monitoring the patient, what is the most common neurological complication resulting from excessive hip flexion in this device?

. Sciatic nerve palsy
. Femoral nerve palsy
. Obturator nerve palsy
. Superior gluteal nerve palsy
. Pudendal nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Excessive hip flexion in a Pavlik harness can cause impingement leading to a femoral nerve palsy. This typically presents as a loss of active knee extension. Conversely, excessive abduction in the harness places the patient at high risk for avascular necrosis (AVN) of the femoral head.

Question 1724

Topic: Pediatric Hip

A 12-year-old overweight boy presents with left knee pain and a limp. Examination reveals obligate external rotation of the left hip during passive hip flexion. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the typical direction of the epiphyseal displacement relative to the femoral neck?

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

Correct Answer & Explanation

. Posterior and inferior

Explanation

In a slipped capital femoral epiphysis (SCFE), the femoral epiphysis typically displaces posteriorly and inferiorly relative to the femoral neck. Conversely, the metaphysis (femoral neck) translates anteriorly and superiorly.

Question 1725

Topic: Pediatric Hip

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip. At the one-week follow-up, she exhibits decreased active knee extension on the treated side. What is the most likely cause?

. Hyperflexion of the hip in the harness
. Excessive abduction of the hip in the harness
. Avascular necrosis of the femoral head
. Transient synovitis
. Improperly sized chest strap

Correct Answer & Explanation

. Hyperflexion of the hip in the harness

Explanation

Hyperflexion of the hip in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a transient femoral nerve palsy. This manifests clinically as decreased active knee extension.

Question 1726

Topic: Pediatric Hip

A 14-year-old boy is diagnosed with an unstable slipped capital femoral epiphysis (SCFE). Which of the following describes the most critical consequence differentiating an unstable SCFE from a stable SCFE?

. Higher risk of chondrolysis
. Inability to ambulate with or without crutches
. Higher risk of avascular necrosis (AVN)
. Requirement for an open reduction
. Increased incidence of contralateral slip

Correct Answer & Explanation

. Higher risk of avascular necrosis (AVN)

Explanation

The Loder classification distinguishes stable from unstable SCFE based on the ability to bear weight. Unstable slips carry a drastically higher risk of avascular necrosis (up to 50%), dictating urgency and care in surgical management.

Question 1727

Topic: Pediatric Hip

A 3-month-old infant is currently being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the routine weekly follow-up, the infant is noted to have an absence of active knee extension on the treated side. What is the most likely cause of this physical finding?

. Obturator nerve palsy from excessive abduction
. Sciatic nerve palsy from excessive extension
. Femoral nerve palsy from excessive flexion
. Avascular necrosis of the femoral head
. Inferior dislocation of the hip

Correct Answer & Explanation

. Femoral nerve palsy from excessive flexion

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, usually caused by excessive hip flexion (typically >120 degrees). It presents as decreased or absent active knee extension. The harness must be adjusted to reduce flexion or temporarily discontinued if the palsy persists. Excessive abduction in a Pavlik harness is associated with an increased risk of avascular necrosis (AVN) of the femoral head.

Question 1728

Topic: Pediatric Hip

Which of the following clinical scenarios serves as the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip in a patient who presents with a unilateral slipped capital femoral epiphysis (SCFE)?

. Patient age of 14 years at initial presentation
. Male gender
. Obesity (BMI > 95th percentile for age)
. Presence of an endocrine disorder such as hypothyroidism
. A Southwick angle greater than 50 degrees on the symptomatic side

Correct Answer & Explanation

. Presence of an endocrine disorder such as hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in unilateral SCFE is highly recommended in patients with specific risk factors that predispose them to bilateral involvement. The strongest indications include an underlying endocrine disorder (e.g., hypothyroidism, panhypopituitarism, renal osteodystrophy), previous pelvic radiation, and very young age at presentation (typically < 10 years for boys and < 9 for girls). Endocrine disorders carry an extremely high risk of bilateral SCFE, justifying prophylactic fixation.

Question 1729

Topic: Pediatric Hip

Prophylactic in situ pinning of the asymptomatic contralateral hip in a patient with a slipped capital femoral epiphysis (SCFE) is most strongly indicated in a patient with which of the following underlying conditions?

. Obesity (> 95th percentile BMI)
. Trisomy 21
. Renal osteodystrophy
. Marfan syndrome
. Sickle cell trait

Correct Answer & Explanation

. Renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip in SCFE is indicated for patients with a high risk of subsequent bilateral slip. Endocrine and metabolic disorders, such as renal osteodystrophy, hypothyroidism, and prior pelvic radiation, are strong indications for prophylactic fixation due to the high incidence of bilaterality.

Question 1730

Topic: Pediatric Hip

A 4-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). The parents note that the infant has stopped kicking her right leg and appears unable to actively extend her right knee. What is the most likely cause?

. Avascular necrosis of the femoral head from excessive abduction
. Sciatic nerve palsy from excessive hip extension
. Femoral nerve palsy from excessive hip flexion
. Obturator nerve palsy from excessive adduction
. Hamstring spasm from inadequate harness sizing

Correct Answer & Explanation

. Femoral nerve palsy from excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion of the hips compressing the nerve against the rim of the pelvis. It presents with decreased active knee extension. Treatment involves adjusting the anterior straps to decrease hip flexion, which usually leads to spontaneous recovery.

Question 1731

Topic: Pediatric Hip

A 6-week-old female infant is brought in for a screening hip ultrasound due to breech presentation. Which of the following ultrasound findings indicates a normal, mature hip?

. Alpha angle < 50 degrees
. Beta angle > 77 degrees
. Alpha angle > 60 degrees
. Less than 50% femoral head coverage
. Dynamic instability on Barlow maneuver

Correct Answer & Explanation

. Alpha angle > 60 degrees

Explanation

According to Graf's classification of developmental dysplasia of the hip (DDH), a normal Type I hip has an alpha angle greater than 60 degrees and a beta angle less than 55 degrees.

Question 1732

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 35 is diagnosed with a unilateral slipped capital femoral epiphysis (SCFE). Which of the following is an accepted indication for prophylactic in situ pinning of the contralateral, asymptomatic hip?

. Age > 14 years
. African American ethnicity
. Underlying renal osteodystrophy
. Anterior slippage of the affected hip
. High BMI alone

Correct Answer & Explanation

. Underlying renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip in SCFE is indicated in patients with underlying metabolic or endocrine disorders (e.g., renal osteodystrophy, hypothyroidism, panhypopituitarism) due to the exceedingly high risk of bilateral progression.

Question 1733

Topic: Pediatric Hip

A 12-year-old overweight boy presents with groin pain and an obligatory external rotation of the hip during active flexion. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most significant risk factor for the development of avascular necrosis (AVN) in this patient?

. Degree of chronicity (> 3 weeks duration)
. Patient obesity (> 95th percentile)
. Inability to bear weight on the affected limb
. Endocrine disorders (e.g., hypothyroidism)
. Prophylactic pinning of the contralateral hip

Correct Answer & Explanation

. Inability to bear weight on the affected limb

Explanation

The inability to bear weight defines an unstable SCFE. Unstable SCFE has a substantially higher risk of avascular necrosis (up to 47%) compared to stable SCFE, which has an AVN rate of less than 10%.

Question 1734

Topic: Pediatric Hip

During routine follow-up of a 12-year-old obese male who underwent in situ pinning for a stable Slipped Capital Femoral Epiphysis (SCFE) 6 months ago, he complains of severe global hip stiffness. Radiographs show joint space narrowing without femoral head collapse. What is the most likely complication?

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

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis presents with severe stiffness and diffuse joint space narrowing on radiographs without initial head collapse. It is a known complication of SCFE, particularly associated with unrecognized pin penetration into the joint.

Question 1735

Topic: Pediatric Hip

A 7-year-old boy is diagnosed with Legg-Calve-Perthes disease. According to the Herring Lateral Pillar Classification, which of the following radiographic findings places the patient in Group C and carries a worse prognosis?

. No involvement of the lateral pillar
. >50% maintenance of lateral pillar height
. <50% maintenance of lateral pillar height
. Central pillar collapse only
. Subchondral fracture (Crescent sign)

Correct Answer & Explanation

. <50% maintenance of lateral pillar height

Explanation

In the Herring Lateral Pillar Classification, Group C is defined by greater than 50% loss of height of the lateral pillar of the femoral head. This indicates significant structural collapse and carries a poor prognosis, often leading to early osteoarthritis.

Question 1736

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During follow-up, the infant is noted to have a lack of active knee extension on the affected side. This complication is most likely the result of which of the following?

. Hyperabduction causing avascular necrosis of the femoral head
. Excessive hip flexion causing femoral nerve palsy
. Excessive hip extension causing sciatic nerve palsy
. Tight posterior straps causing an obturator nerve palsy
. Inferior dislocation of the hip joint

Correct Answer & Explanation

. Excessive hip flexion causing femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of Pavlik harness use and manifests clinically as a loss of active knee extension (decreased quadriceps function). It is caused by excessive hip flexion, which stretches or compresses the femoral nerve as it passes under the inguinal ligament. Treatment involves loosening the anterior straps or temporarily removing the harness until function returns.

Question 1737

Topic: Pediatric Hip

While slipped capital femoral epiphysis (SCFE) typically occurs unilaterally, prophylactic in situ pinning of the asymptomatic contralateral hip is routinely recommended for specific patient populations due to a high risk of subsequent slip. Which of the following is a universally accepted indication for prophylactic contralateral pinning?

. Presentation with a severe (>60 degree) slip on the affected side
. Presence of an underlying endocrinopathy such as hypothyroidism
. Patient age greater than 14 years at the time of initial presentation
. An unstable slip on the initially affected side
. Body mass index (BMI) greater than the 95th percentile

Correct Answer & Explanation

. Presence of an underlying endocrinopathy such as hypothyroidism

Explanation

Contralateral prophylactic pinning in SCFE is indicated in patients with a high likelihood of developing a bilateral slip. Strong, universally accepted indications include the presence of an underlying endocrinopathy (e.g., hypothyroidism, panhypopituitarism), renal osteodystrophy, prior pelvic radiation, or a chronologic age less than 10 years at initial presentation. Severity or stability of the initial slip does not mandate prophylactic pinning of the normal side.

Question 1738

Topic: Pediatric Hip

A 12-year-old obese male presents with left knee pain and a limp. Pelvic radiographs demonstrate a slipped capital femoral epiphysis (SCFE). According to the Loder classification, which finding definitively characterizes this SCFE as 'unstable'?

. Slip angle > 50 degrees on the lateral radiograph
. Presence of a joint effusion on ultrasound
. Inability to bear weight with or without crutches
. Duration of symptoms less than 3 weeks
. Disruption of Klein's line on the AP radiograph

Correct Answer & Explanation

. Inability to bear weight with or without crutches

Explanation

The Loder classification divides Slipped Capital Femoral Epiphysis (SCFE) into stable and unstable based purely on the patient's clinical ability to bear weight. An unstable SCFE is defined by the inability to bear weight, even with the use of crutches. Unstable SCFEs have a significantly higher risk of developing avascular necrosis (up to nearly 50%).

Question 1739

Topic: Pediatric Hip
The Herring Lateral Pillar classification is highly prognostic for the final functional and radiographic outcome in Legg-Calvé-Perthes disease. During which radiographic stage of the disease should this classification be applied?
. Initial/Ischemia stage
. Fragmentation stage
. Reossification stage
. Healing stage
. Residual stage

Correct Answer & Explanation

. Fragmentation stage

Explanation

The Herring Lateral Pillar classification for Legg-Calvé-Perthes disease is properly assessed during the fragmentation stage of the disease, when the extent of epiphyseal collapse is maximally apparent. It evaluates the height of the lateral pillar of the femoral head (Group A: >100%, Group B: >50%, Group C: <50% height maintained).

Question 1740

Topic: Pediatric Hip

A 14-year-old obese male presents with chronic left hip pain and an antalgic gait. Radiographs show a stable slipped capital femoral epiphysis (SCFE). Following in situ pinning, he continues to experience pain and limited range of motion, particularly internal rotation and flexion. What is the most likely long-term complication leading to his persistent symptoms, and what surgical intervention might be indicated?

. Avascular necrosis of the femoral head requiring core decompression
. Chondrolysis necessitating total hip arthroplasty
. Femoroacetabular impingement (FAI) requiring surgical dislocation and osteochondroplasty
. Nonunion of the physis requiring repeat pinning
. Contralateral SCFE requiring prophylactic pinning

Correct Answer & Explanation

. Femoroacetabular impingement (FAI) requiring surgical dislocation and osteochondroplasty

Explanation

SCFE results in a deformity of the proximal femur, specifically retroversion of the femoral head relative to the neck, creating a 'pistol grip' deformity or cam-type impingement. This altered morphology can lead to femoroacetabular impingement (FAI), causing persistent pain, restricted range of motion, and predisposing to premature osteoarthritis, even after successful in situ pinning. Surgical dislocation and osteochondroplasty aim to reshape the femoral head-neck junction to relieve impingement. Avascular necrosis is a significant complication, but persistent pain with specific motion restriction is more indicative of FAI. Chondrolysis and nonunion are less common and typically present differently. Contralateral SCFE is a risk but doesn't explain the persistent ipsilateral symptoms.

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