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4. Pediatrics MCQs

Practice Set 317 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 6321

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from the monkey bars and sustains a Gartland type III extension-type supracondylar humerus fracture. Radiographs demonstrate that the distal fragment is displaced posteromedially. Based on this specific displacement pattern, which nerve is at the highest risk of injury?
. Anterior interosseous nerve
. Radial nerve
. Ulnar nerve
. Musculocutaneous nerve
. Axillary nerve

Correct Answer & Explanation

. Radial nerve

Explanation

In extension-type supracondylar humerus fractures, the direction of displacement of the distal fragment dictates the structures at risk. When the distal fragment is displaced posteromedially, the proximal fragment is driven anterolaterally, putting the radial nerve at the greatest risk of tethering or injury. Conversely, if the distal fragment is displaced posterolaterally, the proximal fragment is driven anteromedially, placing the anterior interosseous nerve (AIN) and the brachial artery at greatest risk. The AIN is the most commonly injured nerve overall in extension-type supracondylar fractures. Ulnar nerve injuries (Option C) are most commonly associated with flexion-type supracondylar fractures or iatrogenic injury from medial pin placement during operative fixation.

Question 6322

Topic: Pediatric Hip
An 8-year-old boy presents with a painless limp of 4 months' duration. Radiographs reveal fragmentation of the capital femoral epiphysis. Which of the following is considered the most important prognostic factor for long-term hip survival and the development of osteoarthritis in a patient with Legg-Calvé-Perthes disease?
. Age at the onset of disease
. Patient gender
. Body Mass Index (BMI)
. Degree of initial pain
. Presence of a positive Trendelenburg sign

Correct Answer & Explanation

. Age at the onset of disease

Explanation

Legg-Calvé-Perthes disease is an idiopathic avascular necrosis of the proximal femoral epiphysis in children. The two most critical prognostic factors for long-term outcomes (i.e., development of premature osteoarthritis and sphericity of the femoral head at skeletal maturity) are the age of the patient at the onset of the disease and the extent of epiphyseal involvement (often measured by the Herring Lateral Pillar classification). Children who develop the disease before age 6 generally have a good prognosis regardless of treatment because they have more time for remodeling. Children over the age of 8 have a worse prognosis and are more likely to benefit from surgical containment (e.g., femoral or pelvic osteotomy) if they fall into Herring Lateral Pillar group B or B/C. Gender, BMI, and initial pain are not the primary determinants of long-term joint survival.

Question 6323

Topic: 4. Pediatrics
A 14-year-old boy sustains an ankle injury while playing soccer. Radiographs and a subsequent CT scan reveal a Salter-Harris III fracture of the anterolateral distal tibial epiphysis with 3 mm of displacement. What is the primary deforming force (ligamentous avulsion) and the typical sequence of distal tibial physeal closure that predisposes to this specific injury?
. Anterior talofibular ligament; closure occurs lateral to medial
. Anterior inferior tibiofibular ligament; closure occurs medial to lateral
. Calcaneofibular ligament; closure occurs anterior to posterior
. Deltoid ligament; closure occurs medial to lateral
. Posterior inferior tibiofibular ligament; closure occurs lateral to medial

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament; closure occurs medial to lateral

Explanation

The patient has a Tillaux fracture, which is a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. This injury occurs uniquely in adolescents due to the asymmetrical closure pattern of the distal tibial physis. The physis closes first centrally, then medially, and finally laterally. During this transitional period (typically ages 12-15), an external rotation force on the foot causes the anterior inferior tibiofibular ligament (AITFL) to avulse the anterolateral epiphysis, which is the only portion of the physis that remains open and vulnerable. The AITFL is the deforming force, and the closure pattern is central to medial to lateral.

Question 6324

Topic: 4. Pediatrics

A 6-year-old girl with spastic quadriplegic cerebral palsy is evaluated in the clinic for routine hip surveillance. Her Gross Motor Function Classification System (GMFCS) level is V. An anteroposterior (AP) pelvis radiograph demonstrates a Reimers migration percentage of 45% on the right hip and 20% on the left. She has no pain, but hip abduction is limited to 20 degrees bilaterally. What is the most appropriate next step in management for the right hip?

. Observation with repeat radiographs in 1 year
. Botulinum toxin injections to the adductors
. Adductor tenotomy alone
. Varus derotational osteotomy (VDRO) of the proximal femur with or without pelvic osteotomy
. Total hip arthroplasty

Correct Answer & Explanation

. Varus derotational osteotomy (VDRO) of the proximal femur with or without pelvic osteotomy

Explanation

Correct Answer: Varus derotational osteotomy (VDRO) of the proximal femur with or without pelvic osteotomyHip displacement is highly prevalent in children with cerebral palsy, particularly those with higher GMFCS levels (IV and V). The Reimers migration percentage (MP) is used to quantify subluxation. An MP > 40-50% indicates significant subluxation that is unlikely to respond to soft tissue releases alone and typically requires bony reconstruction to prevent painful dislocation and facilitate perineal care. The standard of care for a spastic hip with an MP > 40% in a 6-year-old is a proximal femoral varus derotational osteotomy (VDRO), often combined with a pelvic osteotomy (e.g., Dega or San Diego) if there is significant acetabular dysplasia. Soft tissue releases (Option C) are generally reserved for younger children (age < 4) with an MP between 25% and 40%. Observation (Option A) is inappropriate as the hip will likely progress to dislocation.

Question 6325

Topic: 4. Pediatrics
A 2-year-old obese African American female presents with progressive bowing of her left leg. Standing AP radiographs of the lower extremities reveal a metaphyseal-diaphyseal angle (Drennan angle) of 18 degrees on the left, with prominent medial metaphyseal beaking. The right leg has a Drennan angle of 8 degrees. What is the most appropriate initial management for the left lower extremity?
. Reassurance and observation with follow-up in 1 year
. Vitamin D and calcium supplementation
. Knee-ankle-foot orthosis (KAFO) during weight-bearing
. Proximal tibial valgus osteotomy
. Guided growth with a tension band plate on the lateral proximal tibia

Correct Answer & Explanation

. Knee-ankle-foot orthosis (KAFO) during weight-bearing

Explanation

The patient presents with infantile Blount disease (tibia vara), characterized by abnormal endochondral ossification of the medial aspect of the proximal tibial physis. Risk factors include early walking, obesity, and African American descent. The metaphyseal-diaphyseal angle (Drennan angle) is crucial for differentiating Blount disease from physiologic bowing. An angle > 16 degrees is highly predictive of progression to Blount disease. For a child under the age of 3 with Langenskiöld stage I or II disease, the initial treatment of choice is bracing with a KAFO during weight-bearing hours. If the child is older than 3 or 4 years, or if bracing fails, surgical intervention (proximal tibial osteotomy) is indicated. Reassurance is appropriate for physiologic bowing (angle < 10 degrees). Vitamin D is the treatment for rickets, which would present with systemic physeal widening and cupping.

Question 6326

Topic: Pediatric Hip

A 13-year-old boy undergoes in situ single-screw fixation for a stable slipped capital femoral epiphysis (SCFE). Six months postoperatively, he returns to the clinic complaining of severe hip stiffness and pain with any range of motion. On physical examination, he has a 15-degree flexion contracture and global restriction of hip motion. Radiographs demonstrate concentric joint space narrowing of the affected hip without evidence of hardware penetration into the joint. What is the most likely diagnosis?

. Avascular necrosis of the femoral head
. Chondrolysis
. Septic arthritis
. Unrecognized hardware penetration
. Cam-type femoroacetabular impingement

Correct Answer & Explanation

. Chondrolysis

Explanation

Correct Answer: ChondrolysisChondrolysis is a devastating complication of SCFE characterized by the rapid, progressive loss of articular cartilage. It presents clinically with severe global stiffness, pain, and flexion contractures. Radiographically, it is identified by concentric joint space narrowing (typically defined as a joint space < 3 mm). While unrecognized hardware penetration is a known cause of chondrolysis, the vignette explicitly states there is no evidence of hardware penetration, meaning this is idiopathic chondrolysis associated with the SCFE itself. Avascular necrosis (Option A) typically presents with segmental collapse and sclerosis of the femoral head, not isolated concentric joint space narrowing. Septic arthritis (Option C) would present more acutely with systemic signs of infection. Cam impingement (Option E) causes activity-related groin pain and restricted internal rotation, but not global stiffness and concentric joint space loss.

Question 6327

Topic: Pediatric Lower Extremity

A 4-year-old child successfully treated for idiopathic clubfoot with the Ponseti method presents with a relapsed deformity. Gait analysis reveals dynamic supination during the swing phase. What is the most appropriate surgical intervention?

. Split tibialis posterior tendon transfer to the peroneus brevis
. Achilles tendon lengthening alone
. Medial column release
. Tibialis anterior tendon transfer to the lateral cuneiform
. Triple arthrodesis

Correct Answer & Explanation

. Tibialis anterior tendon transfer to the lateral cuneiform

Explanation

Dynamic supination during the swing phase in a relapsed Ponseti-treated clubfoot is typically caused by an overactive tibialis anterior. Transferring the tibialis anterior tendon to the lateral cuneiform balances the foot dorsiflexion.

Question 6328

Topic: 4. Pediatrics
A 4-year-old girl with a BMI in the 99th percentile presents with persistent bilateral genu varum. Standing radiographs demonstrate a metaphyseal-diaphyseal angle of 20 degrees and Langenskiold Stage III changes. What is the most appropriate next step in management?
. Knee-ankle-foot orthosis (KAFO) bracing
. Proximal tibial valgus osteotomy
. Epiphysiodesis of the lateral proximal tibia
. Observation and weight loss counseling
. Medial hemi-epiphysiodesis

Correct Answer & Explanation

. Proximal tibial valgus osteotomy

Explanation

Bracing is generally ineffective for infantile Blount disease in children over age 3 or those with Langenskiold Stage III or higher. Proximal tibial osteotomy with fibular osteotomy is the gold standard to correct the deformity and halt physeal damage.

Question 6329

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department with hip pain. According to the Loder classification, which of the following criteria definitively distinguishes an unstable slipped capital femoral epiphysis (SCFE) from a stable SCFE?

. Duration of symptoms greater than 3 weeks
. Southwick slip angle greater than 50 degrees
. Ability to bear weight with or without crutches
. Presence of a joint effusion on ultrasound
. Degree of posterior tilt on the cross-table lateral radiograph

Correct Answer & Explanation

. Ability to bear weight with or without crutches

Explanation

The Loder classification defines an unstable SCFE purely clinically based on the patient's inability to bear weight, even with assistive devices. Unstable SCFE carries a significantly higher risk of avascular necrosis (up to 47%).

Question 6330

Topic: Pediatric Hip

An 18-month-old girl presents with a painless waddling gait. Pelvic radiographs demonstrate a completely dislocated left hip, a broken Shenton line, and an acetabular index of 42 degrees. What is the most appropriate definitive management?

. Closed reduction and application of a spica cast
. Application of a Pavlik harness
. Open reduction, capsulorrhaphy, and pelvic osteotomy
. Open reduction alone
. Observation until age 4 for skeletal maturity

Correct Answer & Explanation

. Open reduction, capsulorrhaphy, and pelvic osteotomy

Explanation

In walking-age children (over 18 months) with untreated developmental dysplasia of the hip (DDH), closed reduction often fails. Open reduction combined with a pelvic osteotomy (like a Pemberton or Salter) is indicated to address the significant secondary acetabular dysplasia.

Question 6331

Topic: Pediatric Hip

A 9-year-old boy is diagnosed with Legg-Calve-Perthes disease. Radiographs reveal collapse of the lateral pillar, maintaining only 40% of its original height. Based on the Herring lateral pillar classification, what is his group and optimal management?

. Group B, conservative management
. Group B, surgical containment
. Group C, surgical containment
. Group C, conservative management
. Group A, surgical containment

Correct Answer & Explanation

. Group C, surgical containment

Explanation

A lateral pillar maintaining less than 50% of its original height is classified as Herring Group C. In children over 8 years old, outcomes are generally poor regardless of treatment, but some evidence supports surgical containment for borderline B/C or C hips in older children to optimize sphericity.

Question 6332

Topic: Pediatric Hip

A 14-year-old boy presents to the emergency department unable to bear weight on his left leg after a minor fall. Radiographs show a severe left slipped capital femoral epiphysis (SCFE). He is diagnosed with an unstable SCFE. Which of the following is the most significant complication specific to this diagnosis compared to a stable SCFE?

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

Correct Answer & Explanation

. Osteonecrosis of the femoral head

Explanation

Unstable SCFE, defined by the inability to bear weight even with crutches, carries a high risk of osteonecrosis (avascular necrosis) of the femoral head, with rates up to 50%. Stable SCFE has a very low risk of osteonecrosis in comparison.

Question 6333

Topic: Pediatric Lower Extremity

An infant with idiopathic clubfoot is treated with the Ponseti method. After sequential casting corrects the cavus, adductus, and varus deformities, the ankle remains in 15 degrees of equinus. What is the next most appropriate step in management?

. Continue weekly casting until equinus resolves
. Perform a comprehensive posterior medial release
. Perform a percutaneous Achilles tendon tenotomy
. Transfer the tibialis anterior to the lateral cuneiform
. Prescribe a foot abduction orthosis immediately

Correct Answer & Explanation

. Perform a percutaneous Achilles tendon tenotomy

Explanation

Once the cavus, adductus, and varus are corrected, isolated equinus is typically addressed with a percutaneous Achilles tenotomy. This procedure is required in over 80% of idiopathic clubfoot cases treated with the Ponseti method to achieve adequate dorsiflexion.

Question 6334

Topic: Pediatric Hip
A 9-year-old boy presents with a 4-month history of a painless limp. Radiographs demonstrate fragmentation of the right capital femoral epiphysis with >50% lateral pillar involvement. According to the Herring lateral pillar classification, what is his prognostic group and the recommended treatment approach?
. Group A; symptomatic treatment only
. Group B; symptomatic treatment only
. Group B; surgical containment
. Group C; surgical containment
. Group C; total hip arthroplasty

Correct Answer & Explanation

. Group C; surgical containment

Explanation

Greater than 50% loss of lateral pillar height categorizes the patient as Herring Group C, which generally portends a poorer prognosis in Legg-Calvé-Perthes disease. In children over the age of 8, surgical containment (such as a proximal femoral osteotomy) is often recommended to improve outcomes.

Question 6335

Topic: 4. Pediatrics

A 24-month-old girl is evaluated for a waddling gait. Pelvic radiographs reveal a dislocated left hip with a false acetabulum and an acetabular index of 40 degrees. What is the most appropriate definitive management?

. Application of a Pavlik harness
. Closed reduction and spica casting
. Closed reduction and Denis Browne splinting
. Open reduction with pelvic and/or femoral osteotomy
. Observation until skeletal maturity

Correct Answer & Explanation

. Open reduction with pelvic and/or femoral osteotomy

Explanation

In a child older than 18 months with a dislocated hip and significant acetabular dysplasia (high acetabular index), open reduction combined with a pelvic osteotomy (and sometimes a femoral shortening osteotomy) is required. Closed methods are inadequate at this age due to soft tissue contractures and limited bony remodeling potential.

Question 6336

Topic: 4. Pediatrics

A 4-month-old infant is brought to the clinic for a swollen right thigh. Radiographs reveal a transverse fracture of the right midshaft femur. The parents state the child rolled off the couch. What is the most appropriate next step?

. Treat with a Pavlik harness and discharge home
. Treat with a spica cast and discharge home
. Admit to the hospital, obtain a skeletal survey, and consult child protective services
. Perform open reduction and internal fixation
. Reassure the parents that this is a common toddler injury

Correct Answer & Explanation

. Admit to the hospital, obtain a skeletal survey, and consult child protective services

Explanation

Any femur fracture in a non-ambulatory infant is highly suspicious for non-accidental trauma. The history provided does not match the developmental age or injury severity, mandating hospital admission, a skeletal survey, and child protective services involvement.

Question 6337

Topic: 4. Pediatrics
A 13-year-old girl twists her ankle while playing soccer. Radiographs reveal a Salter-Harris III fracture of the anterolateral distal tibia. This specific fracture pattern occurs due to an avulsion force from which of the following ligaments?
. Anterior talofibular ligament
. Calcaneofibular ligament
. Anterior inferior tibiofibular ligament
. Posterior inferior tibiofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. It is caused by an avulsion force from the anterior inferior tibiofibular ligament (AITFL) during a transitional period when the medial physis is closed but the lateral physis remains open.

Question 6338

Topic: 4. Pediatrics

A 6-year-old boy with spastic quadriplegic cerebral palsy is undergoing routine hip surveillance. His pelvic radiograph shows a Reimers migration percentage of 45% bilaterally. What is the most appropriate management?

. Observation with repeat radiographs in 1 year
. Bilateral adductor and iliopsoas tenotomies
. Bilateral varus derotational osteotomies (VDRO) with or without pelvic osteotomies
. Bilateral proximal row carpectomy
. Bilateral total hip arthroplasties

Correct Answer & Explanation

. Bilateral varus derotational osteotomies (VDRO) with or without pelvic osteotomies

Explanation

A Reimers migration percentage greater than 40% in a child with spastic cerebral palsy indicates significant hip subluxation that is unlikely to permanently resolve with soft-tissue release alone. Bony reconstruction with a varus derotational osteotomy (VDRO) and potentially a pelvic osteotomy is the standard of care to prevent dislocation.

Question 6339

Topic: Pediatric Lower Extremity

A 2-week-old infant is undergoing Ponseti casting for idiopathic clubfoot. The treating orthopedic surgeon is manipulating the foot for the second cast. Which of the following represents the correct sequence of deformity correction in the Ponseti method?

. Cavus, Adduction, Varus, Equinus
. Equinus, Cavus, Adduction, Varus
. Cavus, Varus, Adduction, Equinus
. Adduction, Varus, Cavus, Equinus
. Varus, Cavus, Adduction, Equinus

Correct Answer & Explanation

. Cavus, Adduction, Varus, Equinus

Explanation

The Ponseti method corrects the deformities of clubfoot in a specific, sequential order: Cavus, Adductus, Varus, and finally Equinus (remembered by the acronym CAVE). The first cast specifically elevates the first ray to correct the cavus, creating a supinating forefoot to properly align with the hindfoot.

Question 6340

Topic: 4. Pediatrics
A 14-year-old girl sustains an ankle injury while playing soccer. Radiographs show a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. What is the classic mechanism of injury and the typical pattern of distal tibial physeal closure that predisposes to this fracture?
. External rotation; physeal closure proceeds from central to medial, then posterior, and finally anterolateral.
. Internal rotation; physeal closure proceeds from anterolateral to medial, and finally posterior.
. Inversion; physeal closure proceeds from medial to central, and finally lateral.
. Eversion; physeal closure proceeds from posterior to anterior, and finally lateral.
. Plantarflexion; physeal closure occurs simultaneously across the entire physis.

Correct Answer & Explanation

. External rotation; physeal closure proceeds from central to medial, then posterior, and finally anterolateral.

Explanation

A juvenile Tillaux fracture is caused by an external rotation force avulsing the anterolateral epiphysis via the anterior inferior tibiofibular ligament (AITFL). It occurs specifically in adolescents because the distal tibial physis closes asymmetrically: central first, then medial, then posterior, and lastly the anterolateral portion.

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