Menu

4. Pediatrics MCQs

Practice Set 193 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 3841

Topic: 4. Pediatrics

A neonate presents with a long trunk and extremely short limbs. By age 5, the phenotype changes to a short trunk with severe kyphoscoliosis. A prominent "tail" is noted over the sacrum. What is the most likely skeletal dysplasia?

. Metatropic dysplasia
. Campomelic dysplasia
. Thanatophoric dysplasia
. Achondroplasia
. Chondroectodermal dysplasia

Correct Answer & Explanation

. Metatropic dysplasia

Explanation

Metatropic dysplasia is characterized by a reversal of body proportions over time (long trunk in infancy to short trunk in childhood) due to rapidly progressive kyphoscoliosis. A coccygeal "tail" is classic for this disorder.

Question 3842

Topic: 4. Pediatrics

A 9-month-old infant with confirmed achondroplasia presents with a flexible thoracolumbar kyphosis. There are no neurological deficits. What is the most appropriate initial management plan?

. Immediate posterior spinal fusion
. Application of a rigid TLSO brace
. Observation and avoidance of unsupported sitting
. Anterior and posterior spinal fusion
. Laminectomy and decompression

Correct Answer & Explanation

. Observation and avoidance of unsupported sitting

Explanation

Thoracolumbar kyphosis in achondroplasia usually resolves spontaneously when the child begins walking. Avoidance of premature unsupported sitting is the recommended initial management to prevent fixed wedging.

Question 3843

Topic: 4. Pediatrics

A 6-month-old infant with achondroplasia presents with failure to thrive, central sleep apnea, and hyperreflexia in the lower extremities. What is the most appropriate next step in management?

. Observation as this is typical for achondroplasia
. MRI of the craniocervical junction
. Polysomnography alone
. Immediate halo gravity traction
. C1-C2 posterior spinal fusion

Correct Answer & Explanation

. MRI of the craniocervical junction

Explanation

Hyperreflexia and sleep apnea in an infant with achondroplasia are red flags for foramen magnum stenosis causing cervicomedullary compression. An MRI of the craniocervical junction is urgently indicated to assess the need for suboccipital decompression.

Question 3844

Topic: 4. Pediatrics

A 4-year-old boy presents with short trunk dwarfism, prominent joints, and cleft palate. Spinal radiographs show marked platyspondyly with vertical radiolucencies in the vertebral bodies. Which gene mutation is most likely responsible for this phenotype?

. FGFR3
. COMP
. COL2A1
. SLC26A2
. SOX9

Correct Answer & Explanation

. COL2A1

Explanation

The clinical presentation and radiographic finding of coronal clefts in the vertebral bodies are pathognomonic for Kniest dysplasia. This is an autosomal dominant condition caused by mutations in the COL2A1 gene.

Question 3845

Topic: 4. Pediatrics
A 15-year-old female with severe osteogenesis imperfecta (type III) presents with new-onset lower extremity weakness, hyperreflexia, and lower cranial nerve deficits. What is the most likely diagnosis?
. Thoracic disc herniation
. Atlantoaxial rotatory fixation
. Basilar invagination
. Syringomyelia
. Tethered cord syndrome

Correct Answer & Explanation

. Basilar invagination

Explanation

Basilar invagination is a recognized complication in severe forms of osteogenesis imperfecta due to the softening of the skull base. This leads to brainstem compression and lower cranial nerve deficits.

Question 3846

Topic: 4. Pediatrics

An 8-month-old infant with achondroplasia presents with a flexible thoracolumbar kyphosis of 40 degrees. Neurological exam is normal. What is the most appropriate initial management?

. Observation and avoidance of unsupported sitting
. Thoracolumbosacral orthosis (TLSO)
. Posterior spinal fusion
. Anterior and posterior spinal fusion
. Extension casting

Correct Answer & Explanation

. Observation and avoidance of unsupported sitting

Explanation

Thoracolumbar kyphosis is common in infants with achondroplasia and typically resolves with weight-bearing and walking if unsupported sitting is avoided. Bracing or surgery is reserved for progressive, rigid deformities or neurological compromise.

Question 3847

Topic: 4. Pediatrics

A newborn presents with disproportionate short stature, a barrel chest, and a cleft palate. Radiographs reveal delayed ossification of the pubic bones and platyspondyly. Which gene mutation is responsible for this condition?

. FGFR3
. COL1A1
. COL2A1
. COMP
. SLC26A2

Correct Answer & Explanation

. COL2A1

Explanation

Spondyloepiphyseal dysplasia congenita (SEDC) is caused by a defect in the COL2A1 gene, affecting type II collagen. This leads to characteristic manifestations including platyspondyly, delayed epiphyseal ossification, and atlantoaxial instability.

Question 3848

Topic: 4. Pediatrics

A 4-year-old child presents with disproportionate short stature, waddling gait, and joint laxity. Unlike achondroplasia, radiographs show normal interpedicular distances in the lumbar spine. What is the most likely diagnosis?

. Pseudoachondroplasia
. Hypochondroplasia
. Metatropic dysplasia
. Chondrodysplasia punctata
. Kniest dysplasia

Correct Answer & Explanation

. Pseudoachondroplasia

Explanation

Pseudoachondroplasia presents with short-limb dwarfism similar to achondroplasia but features normal facial appearance and normal interpedicular distances in the lumbar spine. It is caused by mutations in the COMP gene.

Question 3849

Topic: 4. Pediatrics

A child with "hitchhiker thumbs", cauliflower ears, and severe cervical kyphosis is diagnosed with diastrophic dysplasia. This condition is inherited in an autosomal recessive pattern due to a mutation in which of the following?

. Fibroblast growth factor receptor 3 (FGFR3)
. Cartilage oligomeric matrix protein (COMP)
. Sulfate transporter (SLC26A2)
. Type X collagen (COL10A1)
. Runx2 transcription factor

Correct Answer & Explanation

. Sulfate transporter (SLC26A2)

Explanation

Diastrophic dysplasia is caused by a mutation in the SLC26A2 gene, which encodes a sulfate transporter. This leads to undersulfation of proteoglycans in the cartilage matrix.

Question 3850

Topic: 4. Pediatrics

A 5-year-old child with a flat midface, prominent joints, and a cleft palate is evaluated for a spinal deformity. Radiographs demonstrate platyspondyly with coronal clefts in the vertebral bodies. Which diagnosis is most consistent with these findings?

. Spondyloepiphyseal dysplasia congenita (SEDC)
. Kniest Dysplasia
. Achondroplasia
. Campomelic dysplasia
. Cleidocranial dysplasia

Correct Answer & Explanation

. Kniest Dysplasia

Explanation

Kniest dysplasia is a type II collagenopathy characterized by "dumbbell-shaped" femora, platyspondyly, and the classic radiographic appearance of coronal clefts in the vertebral bodies during infancy and childhood.

Question 3851

Topic: 4. Pediatrics

A 12-month-old boy with achondroplasia is brought to the clinic for a routine evaluation. Radiographs reveal a thoracolumbar kyphosis of 35 degrees. He has delayed motor milestones but a normal neurological examination. What is the most appropriate next step in management?

. Posterior spinal fusion from T10 to L3
. Extension bracing with a rigid Thoracolumbosacral Orthosis (TLSO)
. Prophylactic wide lumbar laminectomy
. Avoidance of unsupported sitting and encouragement of prone positioning
. Immediate MRI of the entire neuraxis

Correct Answer & Explanation

. Avoidance of unsupported sitting and encouragement of prone positioning

Explanation

Thoracolumbar kyphosis is common in infants with achondroplasia due to axial hypotonia and a large head size, but it typically resolves in over 90% of cases once the child begins to walk. Initial management consists of avoiding unsupported sitting and encouraging prone positioning to develop the extensor musculature.

Question 3852

Topic: 4. Pediatrics

A 7-year-old girl presents with short-limb dwarfism, severe joint laxity, and a completely normal craniofacial appearance. Lateral spine radiographs demonstrate marked platyspondyly with anterior tongue-like projections of the vertebral bodies. Which of the following gene mutations is most likely responsible for her condition?

. FGFR3
. COMP
. COL1A1
. CBFA1
. DTDST

Correct Answer & Explanation

. COMP

Explanation

This patient's clinical and radiographic features are classic for pseudoachondroplasia, which is differentiated from achondroplasia by the absence of craniofacial involvement and the presence of severe joint laxity. It is an autosomal dominant condition caused by mutations in the Cartilage Oligomeric Matrix Protein (COMP) gene.

Question 3853

Topic: 4. Pediatrics

During gradual femoral lengthening using an Ilizarov external fixator, the patient develops a progressive knee flexion and hip abduction contracture. Increased tension in which of the following structures is most likely responsible?

. Rectus femoris
. Iliotibial band
. Gracilis
. Biceps femoris
. Sartorius

Correct Answer & Explanation

. Iliotibial band

Explanation

The iliotibial (IT) band spans both the hip and the knee joints. During femoral lengthening, significant tension in the IT band commonly leads to knee flexion, knee valgus, and hip flexion/abduction contractures.

Question 3854

Topic: 4. Pediatrics

An 18-month-old child presents with bilateral symmetric genu varum. Standing AP radiographs show a metaphyseal-diaphyseal angle (Drennan's angle) of 8 degrees bilaterally. What is the most appropriate management?

. Immediate proximal tibial valgus osteotomy
. Application of guided growth (eight-plates)
. Reassurance and observation
. Application of knee-ankle-foot orthoses (KAFOs)
. Epiphysiodesis of the medial proximal tibia

Correct Answer & Explanation

. Reassurance and observation

Explanation

A metaphyseal-diaphyseal angle (Drennan's angle) of less than 11 degrees in an 18-month-old strongly suggests physiologic bowing rather than infantile Blount's disease. The standard management is reassurance and observation, as this naturally resolves.

Question 3855

Topic: 4. Pediatrics

Using the multiplier method for limb length discrepancy (LLD), what is the estimated final LLD at skeletal maturity for a 4-year-old girl who currently has a congenital LLD of 2.5 cm?

. 2.5 cm
. 3.5 cm
. 5.0 cm
. 7.5 cm
. 10.0 cm

Correct Answer & Explanation

. 5.0 cm

Explanation

The Paley multiplier for a girl at age 4 is approximately 2.0. A congenital LLD grows proportionally with the child, so the current discrepancy of 2.5 cm is multiplied by 2 to yield an estimated 5.0 cm LLD at maturity.

Question 3856

Topic: 4. Pediatrics

A newborn is diagnosed with complete fibular hemimelia. Which of the following associated lower extremity anomalies is most universally expected in this patient?

. Absent medial foot rays
. Posteromedial bowing of the tibia
. Cruciate ligament deficiency
. Developmental dysplasia of the hip
. Patella alta

Correct Answer & Explanation

. Cruciate ligament deficiency

Explanation

Complete fibular hemimelia is highly associated with anterior or anteromedial bowing of the tibia, absent lateral foot rays, equinovalgus foot deformities, and cruciate ligament deficiency (particularly the ACL).

Question 3857

Topic: 4. Pediatrics

When using the Paley Multiplier method to predict leg length discrepancy at skeletal maturity for a congenital discrepancy, the multiplier for a girl at age 3 is approximately 2.0. What underlying assumption does this mathematical method rely on?

. Growth remaining accelerates exponentially during puberty
. Congenital discrepancies increase at a constant proportional rate relative to the normal limb
. The child will experience a premature physeal closure
. Acquired deformities resolve spontaneously by age 8
. Girls reach full skeletal maturity at age 12 exactly

Correct Answer & Explanation

. Congenital discrepancies increase at a constant proportional rate relative to the normal limb

Explanation

The Paley Multiplier method mathematically assumes that congenital limb length discrepancies grow proportionally over time. By multiplying the current discrepancy by age- and gender-specific factors, it predicts the final discrepancy.

Question 3858

Topic: 4. Pediatrics

In the evaluation of an 18-month-old child with significant genu varum, which of the following radiographic parameters most strongly predicts progression to infantile Blount disease rather than resolution of physiologic bowing?

. Mechanical axis deviation (MAD) > 10 mm
. Tibiofemoral angle > 15 degrees
. Metaphyseal-diaphyseal angle > 16 degrees
. Joint line convergence angle > 5 degrees
. Posterior distal femoral angle < 80 degrees

Correct Answer & Explanation

. Metaphyseal-diaphyseal angle > 16 degrees

Explanation

The metaphyseal-diaphyseal angle (Drennan's angle) is used to differentiate physiologic bowing from infantile Blount disease. An angle greater than 16 degrees is highly predictive of progressive infantile Blount disease.

Question 3859

Topic: 4. Pediatrics

The Taylor Spatial Frame (TSF) relies on a specific biomechanical concept to correct complex multi-planar lower limb deformities simultaneously. Which mechanical principle forms the basis of the TSF?

. Ilizarov tension-wire monorail principle
. Sequential planar correction mechanics
. Stewart-Gough platform utilizing six degrees of freedom
. Four-bar linkage kinematic chain
. Rigid body translation restricted to three degrees of freedom

Correct Answer & Explanation

. Stewart-Gough platform utilizing six degrees of freedom

Explanation

The TSF is a hexapod external fixator based on the Stewart-Gough platform. It allows simultaneous correction of complex deformities across all six degrees of freedom (three translations and three rotations).

Question 3860

Topic: 4. Pediatrics

A surgeon seeks to maximize the biomechanical bending and torsional stiffness of a circular Ilizarov frame for tibial lengthening. Which combination of modifications is most effective?

. Increasing ring diameter and decreasing wire tension
. Decreasing distance between the rings and the bone, increasing wire tension, and using olive wires
. Using a 30-degree wire crossing angle instead of 90 degrees
. Substituting all tensioned wires with purely small-diameter smooth pins
. Increasing the distance between the two rings comprising a block

Correct Answer & Explanation

. Decreasing distance between the rings and the bone, increasing wire tension, and using olive wires

Explanation

Frame stability is maximized by using smaller diameter rings (closer to the bone), tensioning wires properly (130 kg), using crossing angles near 90 degrees, and utilizing olive wires to prevent translation.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page