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4. Pediatrics MCQs

Practice Set 200 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 3981

Topic: 4. Pediatrics

A pediatric orthopedic surgeon is reviewing a case series of Dysplasia Epiphysealis Hemimelica (DEH). According to established epidemiological data, which demographic profile is most typical for the initial presentation of this disorder?

. Females between 15 and 20 years of age
. Males between 2 and 14 years of age
. Females between 2 and 14 years of age
. Males between 40 and 50 years of age

Correct Answer & Explanation

. Males between 2 and 14 years of age

Explanation

Correct Answer: Males between 2 and 14 years of ageDEH is a rare skeletal developmental disorder affecting young children. The age of onset is usually between 2 and 14 years, and males are affected twice as frequently as females.

Question 3982

Topic: 4. Pediatrics

Despite its distinct clinical and radiographic presentation, the exact cause of Dysplasia Epiphysealis Hemimelica (DEH) remains a topic of research. According to current literature, what is the established etiology of DEH?

. Autosomal dominant mutation in the EXT1 gene
. Post-traumatic physeal arrest
. The etiology is currently unknown
. Congenital viral infection during the first trimester

Correct Answer & Explanation

. The etiology is currently unknown

Explanation

Correct Answer: The etiology is currently unknownAccording to the provided text, Dysplasia epiphysealis hemimelica is a rare skeletal developmental disorder, and its etiology is still unknown.

Question 3983

Topic: 4. Pediatrics

A 4-year-old child presents with an enlarging mass on the medial aspect of the right knee. Imaging confirms Dysplasia Epiphysealis Hemimelica of the medial distal femoral epiphysis. If left untreated, which of the following deformities is most likely to develop?

. Genu varum
. Genu recurvatum
. Patella alta
. Genu valgum
. Tibia vara

Correct Answer & Explanation

. Genu valgum

Explanation

DEH most frequently affects the medial side of the epiphysis. Overgrowth of the medial distal femoral epiphysis pushes the joint into a valgus alignment, resulting in genu valgum.

Question 3984

Topic: 4. Pediatrics

When performing surgical excision of an epiphyseal mass in a growing child with Dysplasia Epiphysealis Hemimelica, what is the most significant potential local complication related directly to the surgical technique?

. Accelerated longitudinal limb overgrowth
. Spontaneous systemic dissemination of cartilage cells
. Iatrogenic injury to the physis leading to growth arrest or angular deformity
. Pathologic fracture of the adjacent diaphysis
. Severe anaphylactic reaction to exposed chondrocytes

Correct Answer & Explanation

. Iatrogenic injury to the physis leading to growth arrest or angular deformity

Explanation

The mass in DEH is intimately associated with the epiphysis and physis. Surgical excision carries a significant risk of iatrogenic physeal injury, which can result in premature growth arrest or secondary angular deformities.

Question 3985

Topic: 4. Pediatrics

A 6-year-old child presents with limited knee flexion and an asymmetric palpable mass on the medial knee.

Radiographs show multicentric ossification centers adjacent to the medial femoral condyle. What is the standard surgical approach when excising such a symptomatic lesion?

. Intralesional curettage and bone grafting
. Wide margin resection including the entire epiphysis
. Excision of the exostosis while preserving the underlying normal physis and joint surface
. Epiphysiodesis of the contralateral limb to prevent leg length discrepancy
. Radiofrequency ablation of the ossification centers

Correct Answer & Explanation

. Excision of the exostosis while preserving the underlying normal physis and joint surface

Explanation

Surgical management of symptomatic DEH involves careful excision of the cartilaginous overgrowth. It is critical to preserve the native joint cartilage and underlying normal physis to maintain joint congruity and prevent growth arrest.

Question 3986

Topic: 4. Pediatrics

When performing an intra-articular surgical excision of a symptomatic DEH lesion in a growing child, the surgeon must exercise extreme caution to prevent which of the following severe iatrogenic complications?

. Fat embolism syndrome
. Injury to the adjacent physis leading to growth arrest
. Spontaneous arthrodesis of the joint
. Malignant seeding of the joint space
. Permanent lower motor neuron injury

Correct Answer & Explanation

. Injury to the adjacent physis leading to growth arrest

Explanation

Surgical excision carries a significant risk of iatrogenic injury to the physis and the native articular cartilage. Damage to the physis can result in permanent growth arrest or worsening deformity.

Question 3987

Topic: 4. Pediatrics

In the application of an Ilizarov circular frame for tibial lengthening, which of the following modifications will most significantly increase the axial stiffness of the construct?

. Increasing the diameter of the rings
. Decreasing the wire tension from 130 kg to 90 kg
. Increasing the diameter of the transfixing wires
. Using half-pins instead of tensioned wires
. Increasing the distance between the bone and the ring

Correct Answer & Explanation

. Increasing the diameter of the transfixing wires

Explanation

Axial stiffness in a circular frame is proportional to the fourth power of the wire diameter. Therefore, increasing the wire diameter (e.g., from 1.5 mm to 1.8 mm) provides the most significant increase in construct stability.

Question 3988

Topic: 4. Pediatrics



A patient with a complex multi-planar tibial deformity is treated with a hexapod circular external fixator (e.g., Taylor Spatial Frame). What is the fundamental biomechanical advantage of this system over a traditional Ilizarov frame?

. It requires higher wire tension, improving axial stability.
. It relies on pure linear distractors without hinges.
. It allows simultaneous 6-axis correction utilizing a virtual hinge.
. It completely eliminates pin-tract infections.
. It prevents translation during correction entirely.

Correct Answer & Explanation

. It allows simultaneous 6-axis correction utilizing a virtual hinge.

Explanation

Hexapod fixators utilize the Stewart-Gough platform concept to provide 6 degrees of freedom. This allows for simultaneous correction of angulation, translation, length, and rotation in all planes via a computer-generated virtual hinge, without needing to physically rebuild the frame.

Question 3989

Topic: 4. Pediatrics

A 16-year-old male with a history of infantile Blount's disease presents with a complex proximal tibial deformity. What is the classic pathoanatomic triad of the tibial deformity in this condition?

. Varus, internal tibial torsion, and procurvatum
. Valgus, external tibial torsion, and recurvatum
. Varus, external tibial torsion, and recurvatum
. Valgus, internal tibial torsion, and procurvatum
. Varus, internal tibial torsion, and recurvatum

Correct Answer & Explanation

. Varus, internal tibial torsion, and procurvatum

Explanation

The classic multi-planar deformity in severe or untreated infantile Blount's disease consists of tibia vara, internal tibial torsion, and procurvatum (anterior bowing/flexion deformity) due to asymmetric growth depression of the posteromedial proximal tibial physis.

Question 3990

Topic: 4. Pediatrics

Which of the following correctly describes the underlying molecular pathophysiology in Neurofibromatosis Type 1 (NF1)?

. Upregulation of the Wnt/beta-catenin pathway
. Downregulation of the Ras-MAPK pathway
. Upregulation of the Ras-MAPK pathway
. Defect in type 1 collagen synthesis
. Mutation in the FGFR3 gene

Correct Answer & Explanation

. Upregulation of the Ras-MAPK pathway

Explanation

NF1 is caused by a mutation in the NF1 gene on chromosome 17, which encodes the protein neurofibromin. Neurofibromin normally acts as a tumor suppressor by downregulating the Ras-MAPK pathway; its loss leads to unchecked Ras upregulation and cellular proliferation.

Question 3991

Topic: 4. Pediatrics

A 4-year-old child with a history of multiple low-energy fractures, blue sclerae, and dentinogenesis imperfecta is being evaluated. The underlying molecular defect in this condition primarily affects which of the following processes?

. Proliferation of chondrocytes in the resting zone of the physis
. Production and assembly of type II collagen in hyaline cartilage
. Formation of the collagen triple helix due to substitution of glycine residues
. Mineralization of the osteoid matrix by alkaline phosphatase
. Degradation of bone matrix due to defective osteoclast carbonic anhydrase

Correct Answer & Explanation

. Formation of the collagen triple helix due to substitution of glycine residues

Explanation

Osteogenesis Imperfecta is typically caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes. This leads to the substitution of glycine by bulkier amino acids, disrupting the proper formation and folding of the type I collagen triple helix.

Question 3992

Topic: 4. Pediatrics

A 5-year-old boy is diagnosed with Neurofibromatosis Type 1. Which of the following best describes the genetic pathophysiology of this condition?

. Defect in fibrillin-1 leading to abnormal connective tissue
. Mutation in the EXT1 gene causing disorganized physeal growth
. Mutation in the NF1 gene leading to decreased neurofibromin and increased Ras activity
. Mutation in the RET proto-oncogene promoting unregulated kinase activity
. Defect in type I collagen causing defective mineralization

Correct Answer & Explanation

. Mutation in the NF1 gene leading to decreased neurofibromin and increased Ras activity

Explanation

NF1 is an autosomal dominant condition caused by a mutation on chromosome 17. The mutation leads to reduced neurofibromin, an inhibitor of the Ras pathway, causing unregulated cell growth and tumor formation.

Question 3993

Topic: 4. Pediatrics
A 14-month-old child with multiple café-au-lait macules presents with the following tibial deformity. What is the initial orthotic management and primary natural history concern?
. Posteromedial bowing with likely spontaneous resolution
. Anterolateral bowing with a high risk of congenital pseudarthrosis
. Anterolateral bowing with likely spontaneous resolution
. Posteromedial bowing with a high risk of stress fracture
. Genu valgum requiring early guided growth

Correct Answer & Explanation

. Anterolateral bowing with a high risk of congenital pseudarthrosis

Explanation

Anterolateral bowing of the tibia is heavily associated with NF1 and carries a high risk of progressing to congenital pseudarthrosis of the tibia (CPT). Early management involves total contact bracing to protect against fracture.

Question 3994

Topic: 4. Pediatrics

A 5-year-old child with NF1 presents with anterolateral bowing of the tibia and a frank pseudoarthrosis.

What is the gold standard surgical management to achieve union and maintain alignment in this condition?

. Casting and functional bracing
. Excision of the pseudoarthrosis site, autogenous bone grafting, and intramedullary rodding
. Application of an Ilizarov external fixator without resection
. Amputation followed by prosthetic fitting
. Vascularized fibular graft with rigid plate fixation

Correct Answer & Explanation

. Excision of the pseudoarthrosis site, autogenous bone grafting, and intramedullary rodding

Explanation

The gold standard for treating congenital pseudoarthrosis of the tibia in NF1 involves complete resection of the fibrous hamartoma, intramedullary fixation to control alignment and guide growth, and robust autogenous bone grafting.

Question 3995

Topic: 4. Pediatrics

A 4-year-old child presents with a congenital non-union of the tibia.

What is the typical direction of tibial bowing seen prior to fracture in patients with this condition?

. Posteromedial
. Anterolateral
. Anteromedial
. Posterolateral
. Purely anterior

Correct Answer & Explanation

. Anterolateral

Explanation

Congenital pseudarthrosis of the tibia in NF1 is characteristically preceded by anterolateral bowing. In contrast, posteromedial bowing is generally a benign physiological condition that typically resolves spontaneously.

Question 3996

Topic: 4. Pediatrics

A 4-year-old boy presents with the clinical deformity shown in the radiograph.

What is the recommended management for a frank pseudoarthrosis of the tibia in a patient with Neurofibromatosis type 1?

. Observation until skeletal maturity
. Casting and prolonged non-weight bearing
. Resection of the pseudoarthrosis, bone grafting, and rigid internal fixation
. Pulsed electromagnetic field therapy alone
. Immediate below-knee amputation

Correct Answer & Explanation

. Resection of the pseudoarthrosis, bone grafting, and rigid internal fixation

Explanation

Congenital pseudoarthrosis of the tibia in NF1 is managed surgically once a frank pseudoarthrosis develops. Resection of the hamartomatous tissue, robust bone grafting, and rigid stabilization (often intramedullary) are required to achieve union.

Question 3997

Topic: 4. Pediatrics

A pediatrician refers a 5-year-old child for an orthopedic evaluation of scoliosis. During the exam, you note multiple hyperpigmented macules on the child's trunk. According to the NIH diagnostic criteria for Neurofibromatosis Type 1, what is the minimum number and size of these macules required to meet this specific criterion in a prepubertal child?

. Four macules > 5 mm
. Six macules > 5 mm
. Six macules > 15 mm
. Eight macules > 10 mm
. Ten macules > 5 mm

Correct Answer & Explanation

. Six macules > 5 mm

Explanation

According to NIH criteria for NF1, a patient must have six or more cafe-au-lait macules. In prepubertal individuals, these macules must be greater than 5 mm in diameter; in postpubertal individuals, they must be greater than 15 mm.

Question 3998

Topic: 4. Pediatrics

Syringomyelia, characterized by a fluid-filled cavity within the spinal cord, is most commonly associated with which of the following underlying congenital abnormalities?

. Tethered cord syndrome
. Diastematomyelia
. Chiari I malformation
. Neurofibromatosis type 1
. Achondroplasia

Correct Answer & Explanation

. Chiari I malformation

Explanation

Syringomyelia is most frequently associated with a Chiari I malformation, where the cerebellar tonsils herniate through the foramen magnum. This alters CSF flow dynamics, leading to central canal expansion.

Question 3999

Topic: 4. Pediatrics

A 9-year-old child with unilateral pauciarticular JIA presents with a 2 cm leg length discrepancy, with the arthritic limb being longer. She also has a mild knee flexion contracture. What is the primary pathophysiological cause of the limb overgrowth?

. Epiphyseal dysplasia
. Chronic hyperemia stimulating the physis
. Secondary hyperparathyroidism
. Glucocorticoid therapy
. Compensatory hypertrophy from altered gait

Correct Answer & Explanation

. Chronic hyperemia stimulating the physis

Explanation

Chronic synovitis in JIA causes local hyperemia and increased vascularity. This local inflammatory environment stimulates the adjacent physes, commonly leading to accelerated growth and limb lengthening on the affected side.

Question 4000

Topic: 4. Pediatrics

A 6-year-old child with oligoarticular JIA presents with a chronic, persistent unilateral knee effusion. Clinical exam reveals a noticeable limb length discrepancy. What is the most common lower extremity deformity pattern observed in this specific clinical scenario?

. Ipsilateral limb shortening with a varus deformity
. Ipsilateral limb overgrowth with a valgus deformity
. Ipsilateral limb overgrowth with a varus deformity
. Ipsilateral limb shortening with a valgus deformity
. Severe knee flexion contracture without length discrepancy

Correct Answer & Explanation

. Ipsilateral limb overgrowth with a valgus deformity

Explanation

Chronic hyperemia from joint inflammation stimulates the adjacent physes, causing ipsilateral limb overgrowth. Asymmetric stimulation of the distal femoral physis (medial condyle growing faster than lateral) typically produces a valgus deformity.

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