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4. Pediatrics MCQs

Practice Set 23 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 441

Topic: 4. Pediatrics

In patients with cerebral palsy, which of the following factors usually leads to an improvement in walking ability:

. Increased body mass index
. Increased external tibial torsion
. Increased age
. Valgus of the ankle
. Alignment of the foot rocker with the line of progression

Correct Answer & Explanation

. Alignment of the foot rocker with the line of progression

Explanation

Gait in patients with cerebral palsy declines with increases in age, body mass index, external tibial torsion, and significant ankle valgus (due to worsened mechanics of pushoff). Gait is improved by aligning the foot rocker with the line of progression.

Question 442

Topic: Pediatric Lower Extremity

During the initial phase of the Ponseti method for idiopathic clubfoot, which component of the deformity is corrected first?

. Equinus
. Hindfoot varus
. Forefoot adductus
. Cavus
. Internal tibial torsion

Correct Answer & Explanation

. Cavus

Explanation

The sequence of correction in the Ponseti method follows the acronym CAVE: Cavus, Adductus, Varus, and Equinus. Cavus is corrected first by elevating the first ray to align the forefoot with the hindfoot.

Question 443

Topic: Pediatric Lower Extremity

What is the most common cause of relapse in an infant successfully treated for idiopathic clubfoot with the Ponseti method?

. Failure to perform an Achilles tenotomy
. Inadequate initial correction of cavus
. Noncompliance with the foot abduction orthosis
. Muscle imbalance due to an absent anterior tibial artery
. Undiagnosed tethered spinal cord

Correct Answer & Explanation

. Noncompliance with the foot abduction orthosis

Explanation

Noncompliance with the foot abduction orthosis (Denis Browne splint) is universally recognized as the most common cause of relapse following successful initial casting correction.

Question 444

Topic: Pediatric Lower Extremity

During clubfoot treatment using the Ponseti technique, what is the primary indication for performing a percutaneous Achilles tenotomy?

. Prior to the application of the first cast
. When the cavus is fully corrected but adductus remains
. When the midfoot is corrected but ankle dorsiflexion remains less than 10-15 degrees
. Only if there is a recurrent deformity after 6 months of bracing
. Routinely at the age of 12 months

Correct Answer & Explanation

. When the midfoot is corrected but ankle dorsiflexion remains less than 10-15 degrees

Explanation

An Achilles tenotomy is indicated before the final cast when the midfoot is fully corrected (adductus, varus, and cavus are resolved) but residual equinus prevents 10 to 15 degrees of ankle dorsiflexion.

Question 445

Topic: 4. Pediatrics

Congenital vertical talus is most frequently associated with which of the following underlying conditions?

. Achondroplasia
. Arthrogryposis multiplex congenita
. Osteogenesis imperfecta
. Developmental dysplasia of the hip
. Slipped capital femoral epiphysis

Correct Answer & Explanation

. Arthrogryposis multiplex congenita

Explanation

More than 50% of congenital vertical talus cases are associated with neuromuscular or genetic syndromes. Arthrogryposis multiplex congenita and myelomeningocele are the most common associated conditions.

Question 446

Topic: 4. Pediatrics

Which of the following correctly pairs the genetic mutation and inheritance pattern of achondroplasia?

. COL1A1, autosomal dominant
. COMP, autosomal dominant
. FGFR3, autosomal dominant
. FGFR3, autosomal recessive
. SLC26A2, autosomal recessive

Correct Answer & Explanation

. FGFR3, autosomal dominant

Explanation

Achondroplasia is caused by a gain-of-function mutation in the FGFR3 gene. It is inherited in an autosomal dominant pattern, although 80% of cases are due to de novo mutations.

Question 447

Topic: 4. Pediatrics

Which clinical feature distinguishes pseudoachondroplasia from achondroplasia?

. Shortened limbs
. Normal facial appearance
. Bowed legs
. Short stature
. Autosomal dominant inheritance

Correct Answer & Explanation

. Normal facial appearance

Explanation

Unlike achondroplasia, which is characterized by frontal bossing and midface hypoplasia, patients with pseudoachondroplasia have a completely normal facial appearance and normal head circumference.

Question 448

Topic: 4. Pediatrics

A newborn presents with severe, rigid clubfeet, "cauliflower" ear deformities, and "hitchhiker" thumbs. Which of the following is the underlying diagnosis?

. Achondroplasia
. Pseudoachondroplasia
. Diastrophic dysplasia
. Cleidocranial dysplasia
. Osteogenesis imperfecta

Correct Answer & Explanation

. Diastrophic dysplasia

Explanation

Diastrophic dysplasia is an autosomal recessive condition caused by an SLC26A2 sulfate transporter defect. Its clinical hallmarks include hitchhiker thumbs, cystic ear swelling (cauliflower ears), cleft palate, and very rigid clubfeet.

Question 449

Topic: 4. Pediatrics

Which radiographic parameter is most predictive of progression in a 2-year-old child suspected of having infantile Blount disease rather than physiologic genu varum?

. Tibiofemoral angle greater than 15 degrees
. Metaphyseal-diaphyseal angle (Drennan angle) greater than 16 degrees
. Presence of a medial tibial physeal step-off
. Lateral distal femoral angle greater than 90 degrees
. Medial proximal tibial angle less than 85 degrees

Correct Answer & Explanation

. Metaphyseal-diaphyseal angle (Drennan angle) greater than 16 degrees

Explanation

A metaphyseal-diaphyseal angle (Drennan angle) of greater than 16 degrees is highly predictive for the progression of infantile Blount disease. Angles less than 10 degrees typically indicate physiologic bowing.

Question 450

Topic: 4. Pediatrics
A 4-year-old child presents with untreated Langenskiöld stage III infantile Blount disease. What is the most appropriate management?
. Observation and reassurance
. Knee-ankle-foot orthosis (KAFO)
. Proximal tibial valgus osteotomy
. Guided growth with a medial tension band plate
. Epiphysiodesis of the lateral proximal tibia

Correct Answer & Explanation

. Proximal tibial valgus osteotomy

Explanation

For a child older than 3 years or with a Langenskiöld stage III (or higher) deformity, bracing is largely ineffective. A proximal tibial valgus osteotomy is indicated to correct the mechanical axis and unweight the medial physis.

Question 451

Topic: Pediatric Lower Extremity

In a patient with unilateral idiopathic clubfoot, the affected lower extremity typically demonstrates which of the following associated rotational profiles compared to the normal side?

. Internal tibial torsion
. External tibial torsion
. Internal femoral torsion
. External femoral torsion
. No significant torsional difference

Correct Answer & Explanation

. Internal tibial torsion

Explanation

Idiopathic clubfoot is consistently associated with internal tibial torsion of the affected limb. This internal rotation typically persists even after the foot deformities have been fully corrected.

Question 452

Topic: 4. Pediatrics

A 3-month-old infant presents with flexible metatarsus adductus. Which of the following is the most appropriate initial management?

. Serial casting
. Denis Browne splinting
. Prescription of straight-laced corrective shoes
. Observation and parental stretching
. Surgical release of the abductor hallucis

Correct Answer & Explanation

. Observation and parental stretching

Explanation

The vast majority (over 90%) of flexible metatarsus adductus cases in infants resolve spontaneously without aggressive intervention. Observation with gentle stretching by the parents is the most appropriate initial treatment.

Question 453

Topic: Pediatric Lower Extremity

A 2-year-old boy presents with a relapsed clubfoot deformity after successful initial treatment with the Ponseti method. What is the most common cause of recurrence, and what is the appropriate next step in management?

. Noncompliance with bracing; repeat casting
. Noncompliance with bracing; immediate posteromedial release
. Achilles tendon tightness; isolated tenotomy
. Anterior tibial tendon overactivity; split anterior tibial tendon transfer
. Subtalar contracture; lateral column lengthening

Correct Answer & Explanation

. Noncompliance with bracing; repeat casting

Explanation

Noncompliance with the abduction brace is the leading cause of clubfoot recurrence. The initial management of a relapsed clubfoot is a brief period of repeat Ponseti casting, which may be followed by a tendon transfer if dynamic supination persists.

Question 454

Topic: 4. Pediatrics

In a patient with an untreated congenital talipes equinovarus (clubfoot), what is the primary pathoanatomic deformity of the talus?

. Medial deviation and plantarflexion of the talar neck
. Lateral deviation and dorsiflexion of the talar neck
. Shortening of the talar body with lateral rotation
. Enlargement of the talar head with dorsal subluxation
. Medial rotation of the talar body within the mortise

Correct Answer & Explanation

. Medial deviation and plantarflexion of the talar neck

Explanation

In congenital clubfoot, the primary talar deformity is medial deviation and plantarflexion of the talar neck relative to the body. This structural change drives the subsequent medial subluxation of the navicular and calcaneus.

Question 455

Topic: 4. Pediatrics

Which of the following skeletal dysplasias is characterized by a mutation in the COMP (Cartilage Oligomeric Matrix Protein) gene, presenting with normal facies, short-limb dwarfism, and early-onset osteoarthritis?

. Multiple epiphyseal dysplasia
. Achondroplasia
. Diastrophic dysplasia
. Pseudoachondroplasia
. Spondyloepiphyseal dysplasia congenita

Correct Answer & Explanation

. Pseudoachondroplasia

Explanation

Pseudoachondroplasia is caused by mutations in the COMP gene. Patients typically have normal facial features but develop severe short-limb dwarfism, joint laxity, and early-onset osteoarthritis.

Question 456

Topic: 4. Pediatrics

In a newborn with anterolateral bowing of the tibia, what is the most likely associated underlying diagnosis?

. Neurofibromatosis type 1
. Osteogenesis imperfecta
. Fibular hemimelia
. Amniotic band syndrome
. Achondroplasia

Correct Answer & Explanation

. Neurofibromatosis type 1

Explanation

Congenital anterolateral bowing of the tibia is strongly associated with Neurofibromatosis type 1. It often progresses to congenital pseudarthrosis of the tibia and requires specialized surgical management.

Question 457

Topic: 4. Pediatrics

A 1-month-old infant presents with posteromedial bowing of the tibia and a calcaneovalgus foot deformity. What is the expected natural history of this condition without surgical intervention?

. Progression to congenital pseudarthrosis
. Spontaneous resolution of the bowing with a residual leg length discrepancy
. Development of a rigid cavovarus foot deformity
. Rapid progression to a severe equinocavovarus foot
. Complete spontaneous resolution with no leg length inequality

Correct Answer & Explanation

. Spontaneous resolution of the bowing with a residual leg length discrepancy

Explanation

Congenital posteromedial bowing of the tibia generally improves spontaneously with remodeling as the child grows. However, patients typically develop a clinically significant leg length discrepancy requiring eventual equalization.

Question 458

Topic: Pediatric Lower Extremity

During the Ponseti casting for a rigid clubfoot, which sequence correctly describes the order of deformity correction?

. Cavus, adductus, varus, equinus
. Equinus, varus, adductus, cavus
. Varus, adductus, cavus, equinus
. Cavus, varus, adductus, equinus
. Adductus, varus, cavus, equinus

Correct Answer & Explanation

. Cavus, varus, adductus, equinus

Explanation

The Ponseti method systematically corrects clubfoot deformities using the mnemonic CAVE: Cavus (by elevating the first ray), Adductus, Varus, and finally Equinus (often requiring a percutaneous Achilles tenotomy).

Question 459

Topic: Pediatric Lower Extremity
A 3-year-old child with infantile Blount's disease (tibia vara) presents with a Langenskiöld stage III lesion. Which of the following is the most appropriate treatment to correct the deformity and prevent further progression?
. Observation with serial radiographs
. Long leg bracing during nighttime only
. Proximal tibial valgus-derotation osteotomy
. Epiphysiodesis of the lateral proximal tibia
. Distal femoral varus-producing osteotomy

Correct Answer & Explanation

. Proximal tibial valgus-derotation osteotomy

Explanation

Langenskiöld stage III infantile Blount's disease represents a progressive deformity with a "step-off" of the medial metaphysis. Surgical intervention with a proximal tibial valgus and derotation osteotomy is indicated to restore mechanical alignment.

Question 460

Topic: Pediatric Lower Extremity

An infant is born with absent fibulae bilaterally. Which foot deformity is most classically associated with fibular hemimelia?

. Equinocavovarus
. Calcaneovalgus
. Equinovalgus
. Rocker-bottom foot
. Metatarsus adductus

Correct Answer & Explanation

. Equinovalgus

Explanation

Fibular hemimelia typically presents with shortening of the limb, anterior bowing of the tibia, and an equinovalgus foot deformity due to the absent lateral structural support normally provided by the fibula.

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