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4. Pediatrics MCQs

Practice Set 15 of 334

This practice set contains high-yield board review questions covering key concepts in 4. Pediatrics. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 281

Topic: Pediatric Hip

A 12-year-old obese male presents with a 3-week history of left groin pain and a limp. Physical examination reveals obligate external rotation of the left hip during passive flexion. Based on the clinical presentation and image provided, what is the most appropriate initial management for this stable deformity?

. Closed reduction and spica casting
. Percutaneous in situ single-screw fixation
. Open reduction and Dunn osteotomy
. Proximal femoral varus osteotomy
. Observation with non-weight-bearing

Correct Answer & Explanation

. Percutaneous in situ single-screw fixation

Explanation

The patient has a stable Slipped Capital Femoral Epiphysis (SCFE). The gold standard treatment is in situ fixation with a single percutaneous screw to prevent further slippage.

Question 282

Topic: Pediatric Hip
An 8-year-old boy presents with a painless limp of 4 months duration. Anteroposterior pelvis radiograph demonstrates fragmentation of the capital femoral epiphysis with >50% loss of lateral pillar height. According to the Herring Lateral Pillar classification, what group does this represent?
. Group A
. Group B
. Group B/C
. Group C
. Group D

Correct Answer & Explanation

. Group C

Explanation

In the Herring Lateral Pillar classification for Legg-Calvรฉ-Perthes disease, Group C is defined by >50% collapse of the lateral pillar height. This indicates a poor prognosis.

Question 283

Topic: 4. Pediatrics

A 14-year-old boy sustains a hip dislocation in a motor vehicle accident. Recommended treatment is:

. Closed reduction using skeletal traction
. C losed reduction using fluoroscopy
. Open reduction through a posterior approach
. Open reduction through an open approach
. Percutaneous physeal stabilization followed by closed reduction

Correct Answer & Explanation

. C losed reduction using fluoroscopy

Explanation

Hip dislocations in young adolescents require a high-energy trauma, which may result in occult injury to the physis. Numerous reports of physeal separation during the reduction are found in the literature. The authors of the largest series recommend gentle closed reduction under fluoroscopy followed by prophylactic stabilization if there is evidence of physeal injury.

Question 284

Topic: 4. Pediatrics

Risk factors for developmental dysplasia of the hip (DDH) include all of the following except:

. Oligohydramnios
. Firstborn child
. C ongenital muscular torticollis
. Identical twin with DDH
. Male gender

Correct Answer & Explanation

. Male gender

Explanation

Developmental dysplasia of the hip is caused by both genetic and mechanical factors. C rowding and laxity are common factors. Females, pregnancies with oligohydramnios, firstborn children, infants with congenital muscular torticollis, and those with an affected identical twin are at increased risk. Also parental hip dysplasia, congenital dislocation of the knee, and breech position increase the risk of DDH.

Question 285

Topic: 4. Pediatrics

In ultrasound of the infant hip, the alpha angle is defined as:

. The angle between the acetabular roof and the midline of the pelvis
. The acute angle between the lateral wall of the ilium and the extension of the acetabular roof
. The angle between the center of the femoral head and the lateral wall of the ilium
. The angle of the thigh required to produce subluxation of the hip on the sonogram
. The angle between the acetabular roof and the transverse plane

Correct Answer & Explanation

. The acute angle between the lateral wall of the ilium and the extension of the acetabular roof

Explanation

The alpha angle is the acute angle between the lateral wall of the ilium and the extension of the acetabular roof. This angle varies inversely with the acetabular index as seen on plain radiographs.

Question 286

Topic: Pediatric Hip



An obese 12-year-old boy presents with left knee pain and inability to bear weight. Radiographs show a displaced proximal femoral epiphysis. According to the Loder classification, what is the primary risk associated with this specific presentation?

. Chondrolysis
. Osteonecrosis of the femoral head
. Femoroacetabular impingement
. Nonunion
. Premature physeal closure

Correct Answer & Explanation

. Osteonecrosis of the femoral head

Explanation

The inability to bear weight, even with crutches, defines an unstable slipped capital femoral epiphysis (SCFE) in the Loder classification. Unstable SCFE carries a high risk of osteonecrosis, approaching 47% in some series.

Question 287

Topic: 4. Pediatrics

A 6-year-old girl sustains an acute traumatic posterior hip dislocation. What is the most critical factor in minimizing her risk of developing osteonecrosis of the femoral head?

. Open reduction instead of closed reduction
. Post-reduction spica casting for 6 weeks
. Reduction within 6 hours of the injury
. Performing a capsulotomy to decompress a hematoma
. Non-weight bearing for 12 weeks post-injury

Correct Answer & Explanation

. Reduction within 6 hours of the injury

Explanation

The risk of osteonecrosis following a pediatric traumatic hip dislocation is most closely related to the time elapsed before reduction. Prompt reduction, ideally within 6 hours of the injury, significantly decreases this risk.

Question 288

Topic: 4. Pediatrics

Following conservative management of a midshaft femur fracture in a 5-year-old child, the treating orthopedic surgeon should anticipate the maximum amount of femoral overgrowth to occur within what timeframe post-injury?

. First 6 months
. First 18 to 24 months
. 3 to 4 years post-injury
. During the adolescent growth spurt
. After physeal closure

Correct Answer & Explanation

. First 18 to 24 months

Explanation

The hyperemic response following a femur fracture in children stimulates the physis, causing limb overgrowth. This phenomenon is most profound during the first 18 to 24 months after the injury.

Question 289

Topic: 4. Pediatrics

A 3-week-old neonate sustains a midshaft femur fracture during a difficult breech delivery. What is the most appropriate and effective treatment?

. Immediate spica casting
. Pavlik harness
. Open reduction and internal fixation
. Skeletal traction
. Flexible intramedullary nailing

Correct Answer & Explanation

. Pavlik harness

Explanation

For neonates and infants up to 6 months of age, a Pavlik harness provides excellent outcomes for femur fractures. It maintains the hip in flexion and abduction, aligning the proximal fragment with the distal fragment while ensuring ease of care.

Question 290

Topic: Pediatric Hip
A 13-year-old boy underwent in situ pinning of a stable slipped capital femoral epiphysis (SCFE) with a single cannulated screw. Postoperatively, he develops severe stiffness, loss of motion, and global joint space narrowing (< 3 mm) on radiographs without osteonecrosis. What is the most likely diagnosis?
. Septic arthritis
. Chondrolysis
. Femoroacetabular impingement
. Unrecognized unstable slip
. Avascular necrosis

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is characterized by acute articular cartilage destruction, presenting with stiffness and joint space narrowing (<3 mm). It is highly associated with unrecognized hardware penetration into the joint space.

Question 291

Topic: 4. Pediatrics

When utilizing flexible intramedullary nails for a pediatric femur fracture, what technical error is most likely to result in a loss of reduction and subsequent varus or valgus malalignment?

. Leaving the nail ends 2 cm outside the cortex
. Using nails of mismatched diameters
. Contouring the nails to an apex-lateral bow
. Using nails that collectively fill 80% of the canal
. Entry points distal to the physis

Correct Answer & Explanation

. Using nails of mismatched diameters

Explanation

Using mismatched nail diameters leads to asymmetric bending forces within the medullary canal, commonly resulting in varus or valgus malalignment. Nails should be of identical diameter to ensure symmetric three-point fixation.

Question 292

Topic: 4. Pediatrics
A 12-year-old sustains a Delbet Type III (cervicotrochanteric) fracture of the proximal femur. Which of the following complications is most frequently observed following this specific fracture pattern?
. Avascular necrosis of the femoral head
. Coxa vara
. Nonunion
. Premature physeal closure
. Chondrolysis

Correct Answer & Explanation

. Coxa vara

Explanation

Delbet Type III fractures have a lower rate of avascular necrosis compared to Types I and II. However, they are highly associated with the development of coxa vara (often > 20% incidence) if not rigidly fixed or properly reduced.

Question 293

Topic: 4. Pediatrics

A 12-year-old boy presents with a displaced transcervical (Delbet Type II) fracture of the proximal femur. Which of the following complications occurs with the highest frequency in this fracture pattern?

. Nonunion
. Avascular necrosis
. Premature physeal closure
. Chondrolysis
. Coxa vara

Correct Answer & Explanation

. Avascular necrosis

Explanation

Delbet Type I (transepiphyseal) and Type II (transcervical) pediatric proximal femur fractures carry a high rate of avascular necrosis, approaching up to 50% for Type II fractures, due to the vulnerable retinacular blood supply.

Question 294

Topic: 4. Pediatrics

A 3-year-old boy presents with a spiral midshaft femur fracture. The parents state he tripped while running on a carpeted floor. What is an essential component of the initial evaluation?

. Immediate placement of flexible nails
. Skeletal survey and non-accidental trauma workup
. Application of a Pavlik harness
. CT scan of the lower extremity
. Reassurance and discharge in a splint

Correct Answer & Explanation

. Skeletal survey and non-accidental trauma workup

Explanation

A femur fracture in a toddler with a mechanism of injury that does not match the severity of the fracture (e.g., tripping on a carpet) should raise immediate suspicion for child abuse. A skeletal survey and appropriate child protective evaluation are mandatory.

Question 295

Topic: 4. Pediatrics

Which of the following scenarios is an absolute contraindication to the use of a Pavlik harness for the treatment of developmental dysplasia of the hip (DDH)?

. A 3-month-old infant
. Bilateral DDH
. Teratologic hip dislocation
. A positive Ortolani sign
. A positive Galeazzi sign

Correct Answer & Explanation

. Teratologic hip dislocation

Explanation

Teratologic dislocations, such as those associated with arthrogryposis or myelomeningocele, are notoriously stiff and do not typically respond to a Pavlik harness. They usually require rigid casting or surgical reduction.

Question 296

Topic: Pediatric Hip

A 13-year-old obese boy presents with an acute inability to bear weight on his right leg after a minor fall, diagnosed as a slipped capital femoral epiphysis (SCFE). According to the Loder classification, this inability to bear weight defines the slip as unstable. What is the approximate risk of avascular necrosis in this type of SCFE?

. Less than 5%
. 10-15%
. 20-47%
. 70-85%
. Nearly 100%

Correct Answer & Explanation

. 20-47%

Explanation

The Loder classification divides SCFE into stable (able to bear weight) and unstable (unable to bear weight with or without crutches). Unstable SCFE has a dramatically higher rate of avascular necrosis, reported to be between 20% and 47%.

Question 297

Topic: Pediatric Lower Extremity

In the initial casting phase of the Ponseti method for a newborn with idiopathic clubfoot, the first step focuses on correcting which component of the deformity?

. Equinus
. Varus
. Cavus
. Adduction
. Internal rotation

Correct Answer & Explanation

. Cavus

Explanation

The first step in the Ponseti method is correcting the cavus deformity. This is achieved by elevating the first ray, which supines the forefoot to align it with the hindfoot.

Question 298

Topic: Pediatric Hip

A 14-year-old boy is diagnosed with an unstable slipped capital femoral epiphysis (SCFE). To minimize the risk of avascular necrosis and optimize outcomes, what is the widely recommended surgical timing?

. Conservative management with traction
. Urgent reduction and internal fixation within 24 hours
. Delayed pinning after 1 week to allow swelling to subside
. Elective pinning within 4 weeks
. Immediate subtrochanteric osteotomy

Correct Answer & Explanation

. Urgent reduction and internal fixation within 24 hours

Explanation

Unstable SCFE is considered a surgical urgency. Prompt intervention (typically pinning and capsulotomy) within 24 hours has been shown to reduce intracapsular pressure and minimize the risk of avascular necrosis.

Question 299

Topic: 4. Pediatrics

An 8-year-old girl undergoes successful closed reduction of a traumatic posterior hip dislocation within 4 hours. A post-reduction CT scan identifies a 4 mm intra-articular osteochondral fragment. The joint space is clinically symmetric. What is the most appropriate management?

. Observation and protected weight bearing
. Application of a hip spica cast
. Arthroscopic or open surgical excision of the fragment
. Skeletal traction for 3 weeks
. Serial MRI monitoring every 3 months

Correct Answer & Explanation

. Arthroscopic or open surgical excision of the fragment

Explanation

Any retained intra-articular loose body following a pediatric hip dislocation must be surgically removed (arthroscopically or open) to prevent rapid cartilage destruction and secondary early osteoarthritis, regardless of apparent joint space symmetry.

Question 300

Topic: 4. Pediatrics

A 14-year-old girl sustains a Tillaux fracture of the ankle. Which quadrant of the distal tibial physis is the last to close, allowing for this specific avulsion fracture pattern?

. Central
. Anteromedial
. Posteromedial
. Anterolateral
. Posterolateral

Correct Answer & Explanation

. Anterolateral

Explanation

The distal tibial physis closes in a specific, asymmetric pattern: central, then anteromedial, then posteromedial, and finally anterolateral. The open anterolateral physis is vulnerable to avulsion by the anterior inferior tibiofibular ligament.

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