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4. Pediatrics MCQs

Practice Set 298 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 5941

Topic: Pediatric Hip

A 10-year-old girl with delayed fontanelle closure, open skull sutures, and supernumerary teeth is evaluated for a waddling gait. What is the most common orthopedic abnormality requiring surgical intervention in this syndrome?

. Scoliosis
. Atlantoaxial instability
. Coxa vara
. Genu valgum
. Recurrent patellar dislocations

Correct Answer & Explanation

. Coxa vara

Explanation

The patient has cleidocranial dysplasia. Coxa vara is a common finding and represents the most frequent orthopedic manifestation requiring surgical intervention, such as a valgus producing subtrochanteric osteotomy.

Question 5942

Topic: 4. Pediatrics
A 4-year-old child sustains a femur fracture after a minor fall. He has blue sclerae, normal dentition, and no significant hearing loss. Radiographs show generalized osteopenia. What is the most likely Sillence classification for this patient?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type I

Explanation

Osteogenesis Imperfecta (OI) Type I is the mildest and most common form, characterized by blue sclerae, normal dentition, and a quantitative defect in Type I collagen. Type IV patients typically have white sclerae.

Question 5943

Topic: 4. Pediatrics
A 6-year-old girl with osteogenesis imperfecta type III presents with severe anterolateral bowing of the tibia. What is the most appropriate surgical management for her tibial deformity?
. Closed reduction and casting
. External fixation with gradual correction
. Multiple osteotomies with fixed-length intramedullary rodding
. Multiple osteotomies with telescopic intramedullary rodding
. Open reduction and plating

Correct Answer & Explanation

. Multiple osteotomies with telescopic intramedullary rodding

Explanation

The standard of care for severe long bone bowing in growing children with OI is multiple-level osteotomies combined with telescopic intramedullary rodding (e.g., Fassier-Duval rods) to maintain alignment as the child grows.

Question 5944

Topic: 4. Pediatrics

A 2-year-old boy with frontal bossing and rhizomelic shortening of the limbs is diagnosed with a condition caused by a gain-of-function mutation in the FGFR3 gene. In which zone of the physis does this mutation exert its primary effect?

. Reserve zone
. Proliferative zone
. Hypertrophic zone
. Zone of provisional calcification
. Primary spongiosa

Correct Answer & Explanation

. Proliferative zone

Explanation

Achondroplasia is caused by a gain-of-function mutation in FGFR3, which abnormally inhibits chondrocyte proliferation. This effect primarily occurs in the proliferative zone of the physis.

Question 5945

Topic: 4. Pediatrics

A 5-year-old child presents with disproportionate short stature, normal facial features, and a waddling gait. Radiographs show delayed epiphyseal ossification and platyspondyly. A mutation in the COMP gene is identified. Which of the following cellular locations accumulates the abnormal protein?

. Nucleus
. Mitochondria
. Rough endoplasmic reticulum
. Golgi apparatus
. Lysosome

Correct Answer & Explanation

. Rough endoplasmic reticulum

Explanation

Pseudoachondroplasia is caused by mutations in the COMP gene. The mutant cartilage oligomeric matrix protein misfolds and accumulates in the rough endoplasmic reticulum of chondrocytes, causing premature cell death.

Question 5946

Topic: Pediatric Hip

A 7-year-old boy presents with bilateral hip pain and a waddling gait. Radiographs demonstrate small, fragmented proximal femoral epiphyses bilaterally and double-layered patellae. Spine radiographs are completely normal. What is the most likely diagnosis?

. Legg-Calve-Perthes disease
. Spondyloepiphyseal dysplasia congenita
. Multiple epiphyseal dysplasia
. Morquio syndrome
. Pseudoachondroplasia

Correct Answer & Explanation

. Multiple epiphyseal dysplasia

Explanation

Multiple epiphyseal dysplasia (MED) presents with delayed/fragmented epiphyses (often mimicking bilateral Perthes) and characteristic double-layered patellae. The spine is typically normal, distinguishing it from spondyloepiphyseal dysplasias.

Question 5947

Topic: 4. Pediatrics

A 6-year-old child with a barrel-shaped chest, short trunk, and severe coxa vara is diagnosed with spondyloepiphyseal dysplasia congenita (SEDC). Which of the following routine screenings is critical for this patient?

. Echocardiography for aortic root dilation
. Ophthalmologic exam for retinal detachment
. Renal ultrasound for nephrocalcinosis
. Audiometry for sensorineural hearing loss
. DEXA scan for severe osteopenia

Correct Answer & Explanation

. Ophthalmologic exam for retinal detachment

Explanation

SEDC is caused by a type II collagen mutation (COL2A1). Because type II collagen is also highly expressed in the vitreous humor, these patients are at high risk for severe myopia and retinal detachment.

Question 5948

Topic: 4. Pediatrics

An 8-year-old child is evaluated for disproportionate short stature and a waddling gait. He has significant joint laxity but completely normal facial features and normal intelligence. Radiographs demonstrate delayed epiphyseal ossification and irregular metaphyses. Which of the following genes is most likely mutated?

. FGFR3
. COL1A1
. COMP
. SOX9
. RUNX2

Correct Answer & Explanation

. COMP

Explanation

The patient has pseudoachondroplasia, which is an autosomal dominant condition caused by mutations in the Cartilage Oligomeric Matrix Protein (COMP) gene. Unlike true achondroplasia (FGFR3 mutation), these patients present with normal facies and typically normal intelligence.

Question 5949

Topic: 4. Pediatrics

A 15-year-old girl presents for evaluation of hypermobility of the shoulders.

A radiograph of her chest and shoulders is provided. Which of the following orthopaedic conditions is most frequently associated with the underlying syndrome shown?

. Atlantoaxial rotatory subluxation
. Coxa vara
. Slipped capital femoral epiphysis
. Proximal focal femoral deficiency
. Madelung deformity

Correct Answer & Explanation

. Coxa vara

Explanation

The image demonstrates absent or severely hypoplastic clavicles, pathognomonic for cleidocranial dysplasia (RUNX2 mutation). A very common orthopaedic manifestation in these patients is coxa vara, which may require a valgus-producing subtrochanteric osteotomy.

Question 5950

Topic: 4. Pediatrics

A 14-month-old infant with achondroplasia is noted to have a prominent thoracolumbar kyphosis. Neurological examination is normal. What is the most appropriate management strategy?

. Immediate anterior spinal fusion
. Posterior spinal fusion with instrumentation
. Extension bracing (TLSO)
. Avoidance of unsupported sitting and observation
. Surgical decompression of the foramen magnum

Correct Answer & Explanation

. Avoidance of unsupported sitting and observation

Explanation

Correct Answer: Avoidance of unsupported sitting and observationThoracolumbar kyphosis is very common in infants with achondroplasia, primarily due to hypotonia and a large head size. The vast majority of these deformities are flexible and will resolve spontaneously once the child begins to walk and develops lumbar lordosis. The standard of care is to avoid premature unsupported sitting and to observe. Bracing or surgery is only indicated if the kyphosis becomes rigid or persists into early childhood (usually beyond 3 years of age).

Question 5951

Topic: 4. Pediatrics

A neonate presents with a disproportionately short trunk, prominent joints, and a cleft palate. Radiographs reveal 'dumbbell-shaped' femora and distinct coronal clefts in the vertebral bodies. What is the most likely diagnosis?

. Achondroplasia
. Pseudoachondroplasia
. Kniest dysplasia
. Cleidocranial dysplasia
. Chondrodysplasia punctata

Correct Answer & Explanation

. Kniest dysplasia

Explanation

Correct Answer: Kniest dysplasiaKniest dysplasia is a type II collagenopathy (COL2A1 mutation) characterized by short-trunk dwarfism, prominent joints, midface hypoplasia, and cleft palate. The radiographic hallmarks include 'dumbbell-shaped' long bones (especially femora) due to broad metaphyses and epiphyses, and coronal clefts in the vertebral bodies seen on lateral spine radiographs in infancy.

Question 5952

Topic: 4. Pediatrics

A 2-year-old boy with achondroplasia presents with central sleep apnea, delayed motor milestones, and hyperreflexia in the lower extremities. What is the most appropriate next step in management?

. Polysomnography and CPAP titration
. MRI of the craniocervical junction
. Lumbar puncture to assess CSF pressure
. Application of a halo vest
. Observation as this is a self-limiting condition

Correct Answer & Explanation

. MRI of the craniocervical junction

Explanation

Correct Answer: MRI of the craniocervical junctionInfants and young children with achondroplasia are at high risk for foramen magnum stenosis due to abnormal endochondral ossification of the skull base. Symptoms of severe compression include central sleep apnea, hyperreflexia, hypotonia, and delayed milestones. This is a life-threatening condition that can lead to sudden death. An urgent MRI of the craniocervical junction is required to evaluate the degree of compression, which may necessitate suboccipital decompression.

Question 5953

Topic: 4. Pediatrics

Spondyloepiphyseal dysplasia congenita (SEDC) is characterized by disproportionate short-trunk dwarfism. Which of the following genetic mutations and associated spinal anomalies are characteristic of this condition?

. FGFR3 mutation; thoracolumbar kyphosis
. COL1A1 mutation; basilar invagination
. COL2A1 mutation; odontoid hypoplasia
. SLC26A2 mutation; cervical spina bifida occulta
. COMP mutation; multiple cervical hemivertebrae

Correct Answer & Explanation

. COL2A1 mutation; odontoid hypoplasia

Explanation

Correct Answer: COL2A1 mutation; odontoid hypoplasiaSpondyloepiphyseal dysplasia congenita (SEDC) is an autosomal dominant disorder caused by mutations in the COL2A1 gene, which encodes type II collagen. Major spinal manifestations include platyspondyly and odontoid hypoplasia, the latter leading to atlantoaxial instability. FGFR3 is associated with achondroplasia, COL1A1 with osteogenesis imperfecta, SLC26A2 with diastrophic dysplasia, and COMP with pseudoachondroplasia.

Question 5954

Topic: 4. Pediatrics

A neonate is evaluated for a skeletal dysplasia. Radiographs reveal dumbbell-shaped femora, platyspondyly, and distinct coronal clefts in the vertebral bodies. The patient has a flat midface and prominent eyes. Which of the following is the most likely diagnosis?

. Achondroplasia
. Diastrophic dysplasia
. Kniest dysplasia
. Cleidocranial dysplasia
. Chondrodysplasia punctata

Correct Answer & Explanation

. Kniest dysplasia

Explanation

Correct Answer: Kniest dysplasiaKniest dysplasia is a type II collagenopathy (COL2A1 mutation). Classic radiographic findings include dumbbell-shaped femora (due to broad metaphyses and epiphyses) and coronal clefts in the vertebral bodies (due to delayed fusion of the anterior and posterior ossification centers). Patients typically have a flat midface, prominent eyes, and severe kyphoscoliosis.

Question 5955

Topic: 4. Pediatrics

A 6-month-old infant with achondroplasia is evaluated for delayed motor milestones. A sleep study reveals severe central sleep apnea. MRI of the cervicomedullary junction shows effacement of the subarachnoid space with T2 signal changes in the upper cervical cord. What is the most appropriate definitive management?

. Continuous positive airway pressure (CPAP) at night
. Suboccipital decompression and C1 laminectomy
. Occipitocervical fusion
. Observation as this typically resolves with growth
. Administration of recombinant human growth hormone

Correct Answer & Explanation

. Suboccipital decompression and C1 laminectomy

Explanation

Correct Answer: Suboccipital decompression and C1 laminectomyForamen magnum stenosis is a critical complication in infants with achondroplasia, caused by premature fusion of the synchondroses of the skull base. Symptoms include central sleep apnea, hyperreflexia, and delayed motor milestones. MRI showing cord compression with T2 signal changes is an absolute indication for urgent surgical decompression, typically involving a suboccipital craniectomy and C1 laminectomy to relieve pressure on the cervicomedullary junction. Fusion is rarely required initially unless instability is present.

Question 5956

Topic: 4. Pediatrics

A 6-month-old infant with achondroplasia is brought to the clinic by her parents, who are concerned about a noticeable 'hump' in her lower back. On examination, a flexible thoracolumbar kyphosis is present. Neurological examination is normal. What is the most appropriate initial management for this spinal deformity?

. Immediate posterior spinal fusion to prevent progression
. Anterior and posterior spinal fusion
. Application of a custom Thoracolumbosacral Orthosis (TLSO)
. Observation and strict avoidance of unsupported sitting
. Urgent MRI of the spine followed by foramen magnum decompression

Correct Answer & Explanation

. Observation and strict avoidance of unsupported sitting

Explanation

Correct Answer: Observation and strict avoidance of unsupported sittingThoracolumbar kyphosis is present in over 90% of infants with achondroplasia. It is primarily postural, exacerbated by hypotonia and a large head size. The natural history is spontaneous resolution in the vast majority of cases once the child develops adequate truncal tone and begins to walk. The most appropriate initial management is observation and counseling parents to avoid unsupported sitting, which exacerbates the deformity. Bracing or surgery is reserved for severe, rigid, or progressive cases that do not resolve with weight-bearing.

Question 5957

Topic: 4. Pediatrics

An infant is evaluated for a skeletal dysplasia. Spinal radiographs reveal characteristic coronal clefts in the vertebral bodies. Appendicular radiographs show 'dumbbell-shaped' femora. Which of the following is the most likely diagnosis?

. Achondroplasia
. Diastrophic dysplasia
. Kniest dysplasia
. Cleidocranial dysplasia
. Chondrodysplasia punctata

Correct Answer & Explanation

. Kniest dysplasia

Explanation

Correct Answer: Kniest dysplasiaKniest dysplasia is a Type II collagenopathy (COL2A1 mutation). It is classically characterized radiographically by coronal clefts in the vertebral bodies (due to delayed fusion of the anterior and posterior ossification centers) and 'dumbbell-shaped' long bones (especially the femora) with broad, prominent metaphyses and enlarged epiphyses. Patients also frequently develop severe kyphoscoliosis.

Question 5958

Topic: 4. Pediatrics

Which of the following genetic mutations is correctly paired with its corresponding skeletal dysplasia that heavily involves the spine?

. FGFR3 - Spondyloepiphyseal Dysplasia Congenita
. COL2A1 - Achondroplasia
. COMP - Pseudoachondroplasia
. DTDST - Morquio Syndrome
. GALNS - Diastrophic Dysplasia

Correct Answer & Explanation

. COMP - Pseudoachondroplasia

Explanation

Correct Answer: COMP - PseudoachondroplasiaPseudoachondroplasia is caused by mutations in the Cartilage Oligomeric Matrix Protein (COMP) gene. Achondroplasia is caused by mutations in the Fibroblast Growth Factor Receptor 3 (FGFR3) gene. Spondyloepiphyseal Dysplasia Congenita (SEDC) is caused by mutations in the Type II collagen gene (COL2A1). Diastrophic dysplasia is caused by mutations in the DTDST (SLC26A2) gene. Morquio syndrome A is caused by a deficiency in the GALNS enzyme.

Question 5959

Topic: 4. Pediatrics

An 8-month-old infant with achondroplasia is brought to the clinic. The parents are concerned about a prominent bump on the baby's lower back. Examination reveals a flexible thoracolumbar kyphosis. Neurological exam is normal. What is the most appropriate management?

. Prescribe a thoracolumbosacral orthosis (TLSO) for 23 hours a day
. Schedule for prophylactic posterior spinal fusion
. Prohibit unsupported sitting and encourage prone positioning
. Perform an MRI of the spine to rule out a tethered cord
. Reassure the parents that no intervention or lifestyle modification is needed

Correct Answer & Explanation

. Prohibit unsupported sitting and encourage prone positioning

Explanation

Correct Answer: CThoracolumbar kyphosis is present in over 90% of infants with achondroplasia. It is typically flexible and caused by hypotonia and a large head size. The most appropriate initial management is to prohibit unsupported sitting and encourage prone positioning to develop the paraspinal musculature. With this conservative approach, the vast majority of these kyphotic deformities resolve spontaneously once the child begins walking and develops a lumbar lordosis. Bracing is reserved for persistent or rigid curves.

Question 5960

Topic: 4. Pediatrics

A 6-year-old girl presents with short-limb dwarfism, a normal facial appearance, and normal intelligence. Radiographs show anterior tongue-like projections of the vertebral bodies and irregular, fragmented epiphyses. What is the most likely diagnosis?

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

Correct Answer & Explanation

. Pseudoachondroplasia

Explanation

Correct Answer: APseudoachondroplasia is characterized by disproportionate short-limb dwarfism, but unlike achondroplasia, patients have a normal facial appearance and head circumference. Radiographically, the spine in childhood classically shows anterior tongue-like projections of the vertebral bodies (which later evolve into platyspondyly). The epiphyses are irregular and fragmented. It is caused by a mutation in the COMP (Cartilage Oligomeric Matrix Protein) gene.

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