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4. Pediatrics MCQs

Practice Set 289 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 5761

Topic: Pediatric Upper Extremity & Spine

When evaluating a 14-year-old female with adolescent idiopathic scoliosis, the Center Sacral Vertical Line (CSVL) falls between the medial aspect of the pedicle and the lateral margin of the apical lumbar vertebra. According to the Lenke Classification system, what is the correct lumbar modifier?

. Modifier A
. Modifier B
. Modifier C
. Modifier D
. Modifier E

Correct Answer & Explanation

. Modifier B

Explanation

In the Lenke classification, a lumbar modifier B is assigned when the CSVL falls between the medial border of the pedicle and the lateral margin of the apical lumbar vertebra. Modifier A is when it passes between the pedicles, and C is when it falls completely medial to the lateral margin.

Question 5762

Topic: 4. Pediatrics

A newborn is evaluated for frontal bossing, midface hypoplasia, and rhizomelic shortening of the limbs. Genetic testing confirms a gain-of-function mutation in the FGFR3 gene. Which physeal zone is primarily affected by this mutation?

. 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 the FGFR3 gene. This mutation inhibits normal chondrocyte proliferation, directly affecting the proliferative zone of the physis.

Question 5763

Topic: 4. Pediatrics
A newborn infant is noted to have a congenital scoliosis secondary to a fully segmented hemivertebra at T8. Which of the following screening examinations is mandatory as part of the initial workup?
. Complete skeletal survey
. Renal ultrasound and echocardiogram
. Cranial ultrasound
. Genetic microarray
. Serum protein electrophoresis

Correct Answer & Explanation

. Renal ultrasound and echocardiogram

Explanation

Congenital scoliosis is frequently associated with VACTERL anomalies, particularly genitourinary (up to 30%) and cardiovascular defects. Therefore, a renal ultrasound and an echocardiogram are mandatory components of the initial evaluation.

Question 5764

Topic: Pediatric Upper Extremity & Spine

A 13-year-old premenarchal female with a Risser 0 score presents with a 24-degree right thoracic idiopathic scoliosis. What is the primary indication for initiating brace treatment in this patient?

. Curve greater than 45 degrees
. Curve 25-40 degrees in a growing child (Risser 0-2)
. Curve less than 20 degrees with a family history of scoliosis
. Skeletally mature patient with a 30-degree curve
. Presence of a structural compensatory lumbar curve

Correct Answer & Explanation

. Curve 25-40 degrees in a growing child (Risser 0-2)

Explanation

Bracing in adolescent idiopathic scoliosis is indicated for curves between 25 and 40 degrees in skeletally immature patients (Risser 0-2) to prevent curve progression. Curves greater than 45-50 degrees often require surgical intervention.

Question 5765

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal female presents with a right thoracic adolescent idiopathic scoliosis (AIS) measuring 25 degrees. Her Risser stage is 0. Based on standard progression risk charts, what is her approximate risk of curve progression?

. 10%
. 22%
. 68%
. 90%
. 100%

Correct Answer & Explanation

. 68%

Explanation

Risk of progression in AIS depends heavily on remaining growth and current curve magnitude. A 20-29 degree curve in a Risser 0 or 1 patient has an approximately 68% risk of progression.

Question 5766

Topic: 4. Pediatrics

A 4-year-old boy with achondroplasia presents with delayed walking. Physical examination reveals a flexible thoracolumbar kyphosis. What is the most appropriate initial management for his spinal deformity?

. Immediate posterior spinal fusion
. Anterior and posterior spinal fusion
. Observation and physical therapy
. Bracing with a TLSO
. Foramen magnum decompression

Correct Answer & Explanation

. Observation and physical therapy

Explanation

Thoracolumbar kyphosis is present in up to 90% of infants with achondroplasia but typically resolves spontaneously as the child begins to walk. Observation is the most appropriate initial management unless the curve becomes fixed.

Question 5767

Topic: 4. Pediatrics

A 10-year-old boy presents with multiple bony prominences around his knees and wrists.

He is diagnosed with Multiple Hereditary Exostoses (MHE). What is the underlying pathophysiology of this disorder?

. Mutation in the FGFR3 gene
. Defective proliferation of chondrocytes in the resting zone
. Loss of function mutations in the EXT1 or EXT2 genes
. Overexpression of the SOX9 transcription factor
. Mutation in the COL1A1 gene

Correct Answer & Explanation

. Loss of function mutations in the EXT1 or EXT2 genes

Explanation

Multiple Hereditary Exostoses is primarily caused by autosomal dominant mutations in EXT1 or EXT2 genes, which are involved in heparan sulfate synthesis. This leads to disorganized chondrocyte proliferation and osteochondroma formation.

Question 5768

Topic: 4. Pediatrics
A newborn presents with multiple fractures, blue sclerae, and severe osteopenia. Which type of Osteogenesis Imperfecta is universally lethal in the perinatal period?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type II

Explanation

Osteogenesis Imperfecta Type II is the most severe form of the disease. It is universally lethal in the perinatal period due to severe pulmonary hypoplasia and profound skeletal fragility.

Question 5769

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal female presents for evaluation of adolescent idiopathic scoliosis. Radiographs demonstrate a 28-degree right thoracic curve. Her Risser stage is 0. What is the most appropriate next step in management?

. Observation with repeat radiographs in 6 months
. Initiation of a thoracolumbosacral orthosis (TLSO)
. Nighttime-only bending brace
. Posterior spinal fusion
. Physical therapy and Schroth exercises

Correct Answer & Explanation

. Initiation of a thoracolumbosacral orthosis (TLSO)

Explanation

Bracing is indicated for immature patients (Risser 0-2, premenarchal) with curves between 25 and 45 degrees. A TLSO worn for at least 18 hours a day has been shown to significantly decrease the risk of curve progression to surgical magnitude.

Question 5770

Topic: 4. Pediatrics
Osteogenesis imperfecta (OI) leads to frequent fractures and progressive spinal deformity. According to the Sillence classification, which type of OI is characterized as perinatal lethal?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type II

Explanation

In the Sillence classification of osteogenesis imperfecta, Type II is the perinatal lethal form, often resulting in death in utero or shortly after birth due to severe pulmonary hypoplasia and profound skeletal fragility. Type I is mild, and Type III is the most severe non-lethal form.

Question 5771

Topic: 4. Pediatrics

A neonate is evaluated for severe micromelic dwarfism. Clinical examination reveals a "hitchhiker" thumb, cauliflower ears, and rigid clubfeet. Radiographs of the spine are notable for severe kyphoscoliosis. A mutation in which of the following genes is responsible for this condition?

. FGFR3
. COMP
. COL1A1
. SLC26A2
. RUNX2

Correct Answer & Explanation

. SLC26A2

Explanation

The clinical presentation is classic for Diastrophic Dysplasia. It is an autosomal recessive disorder caused by a mutation in the SLC26A2 (DTDST) gene, which encodes a sulfate transporter critical for normal cartilage matrix sulfation.

Question 5772

Topic: Pediatric Upper Extremity & Spine
A 12-year-old premenarchal female (Risser 0) presents with a right thoracic adolescent idiopathic scoliosis curve measuring 35 degrees. According to the Bracing in Adolescent Idiopathic Scoliosis Trial (BRAIST), which of the following is the most appropriate recommendation to prevent curve progression to surgical magnitude?
. Observation with 6-month radiographs
. Physical therapy focusing on core strengthening
. Night-time only bending brace
. Rigid thoracolumbosacral orthosis (TLSO) wear for at least 18 hours per day
. Posterior spinal fusion

Correct Answer & Explanation

. Rigid thoracolumbosacral orthosis (TLSO) wear for at least 18 hours per day

Explanation

The BRAIST trial demonstrated that rigid bracing (TLSO) significantly decreases the progression of high-risk adolescent idiopathic scoliosis curves to the surgical threshold (โ‰ฅ50 degrees). A dose-response relationship was found, with maximum benefit observed in patients wearing the brace for at least 18 hours per day.

Question 5773

Topic: 4. Pediatrics

A 4-year-old boy with frontal bossing, rhizomelic shortening, and a trident hand presents for an orthopedic evaluation. He has a known mutation in the FGFR3 gene. Which of the following best describes the pathophysiologic mechanism of his bone dysplasia?

. Decreased degradation of cartilage matrix
. Gain-of-function mutation causing inhibition of chondrocyte proliferation
. Loss-of-function mutation leading to disorganized physeal growth
. Defective type I collagen synthesis
. Impaired mineralization of osteoid

Correct Answer & Explanation

. Gain-of-function mutation causing inhibition of chondrocyte proliferation

Explanation

Achondroplasia is the most common form of short-limbed dwarfism and is caused by an autosomal dominant gain-of-function mutation in FGFR3. This overactive receptor abnormally inhibits chondrocyte proliferation and differentiation within the proliferative zone of the physis.

Question 5774

Topic: Pediatric Hip
A 3-year-old child presents with a limp and pain in the right hip. Radiographs show flattening and sclerosis of the right femoral head epiphysis, with widening of the medial joint space. What is the most likely diagnosis?
. Developmental dysplasia of the hip (DDH)
. Septic arthritis of the hip
. Transient synovitis of the hip
. Legg-Calvรฉ-Perthes disease (LCPD)
. Slipped capital femoral epiphysis (SCFE)

Correct Answer & Explanation

. Legg-Calvรฉ-Perthes disease (LCPD)

Explanation

The radiographic findings of flattening and sclerosis of the femoral head epiphysis, along with widening of the medial joint space, are classic for Legg-Calvรฉ-Perthes disease (LCPD), an idiopathic avascular necrosis of the femoral head in children typically aged 4-8 years. DDH involves acetabular and femoral head dysplasia. Septic arthritis presents with acute, severe pain and fever, and radiographic changes are typically joint effusions and cartilage destruction. Transient synovitis is a self-limiting inflammatory condition with minimal radiographic changes. SCFE usually occurs in adolescents (10-16 years) and involves a posterior and inferior slippage of the femoral head epiphysis.

Question 5775

Topic: 4. Pediatrics

A 10-year-old boy presents with progressive cavovarus foot deformity, hammer toes, and bilateral distal muscle weakness and atrophy, particularly affecting the peroneal muscles. He also reports difficulties with fine motor skills in his hands. Deep tendon reflexes are diminished, and sensation is decreased in a stocking-glove distribution. What is the most likely diagnosis?

. Duchenne muscular dystrophy
. Spina bifida
. Cerebral palsy
. Charcot-Marie-Tooth disease (CMT)
. Friedreich's ataxia

Correct Answer & Explanation

. Charcot-Marie-Tooth disease (CMT)

Explanation

The constellation of progressive cavovarus foot deformity, hammer toes, distal muscle weakness and atrophy (especially peroneal), hand intrinsic weakness, diminished deep tendon reflexes, and stocking-glove sensory loss is highly characteristic of Charcot-Marie-Tooth disease (CMT). CMT is a hereditary motor and sensory neuropathy (HMSN), the most common inherited neurological disorder, affecting peripheral nerves. Duchenne muscular dystrophy is a primary muscle disorder with proximal weakness. Spina bifida is a congenital spinal cord defect. Cerebral palsy is a brain injury affecting motor control. Friedreich's ataxia primarily affects the cerebellum and spinal cord, presenting with ataxia, dysarthria, and scoliosis, though cavovarus feet can also occur.

Question 5776

Topic: Pediatric Hip

Which of the following is the most reliable radiographic sign for detecting a slipped capital femoral epiphysis (SCFE)?

. Widening of the physis
. Irregularity of the femoral head
. Trethowan's sign (Klein's line failing to intersect the lateral part of the femoral head)
. Decreased femoral neck-shaft angle
. Increased medial clear space

Correct Answer & Explanation

. Trethowan's sign (Klein's line failing to intersect the lateral part of the femoral head)

Explanation

Trethowan's sign, or Klein's line, is considered the most reliable radiographic sign for detecting SCFE on an anteroposterior (AP) view. Klein's line is drawn along the superior border of the femoral neck; normally, it should intersect a portion of the femoral head epiphysis. In SCFE, due to posterior and inferior slippage, Klein's line will fail to intersect or will intersect a smaller portion of the epiphysis. While widening of the physis and decreased femoral neck-shaft angle can be present, Klein's line is the most sensitive and specific sign for early diagnosis on standard AP radiographs.

Question 5777

Topic: 4. Pediatrics

A 4-year-old presents with a congenital muscular torticollis. On examination, there is right sternocleidomastoid contracture, with the head tilted to the right and rotated to the left. What is the most important initial management strategy?

. Immediate surgical release of the sternocleidomastoid muscle.
. Observation and reassurance, as most cases resolve spontaneously.
. Intensive physical therapy focusing on stretching and strengthening exercises.
. Casting to maintain the head in a corrected position.
. Botulinum toxin injection into the affected sternocleidomastoid.

Correct Answer & Explanation

. Intensive physical therapy focusing on stretching and strengthening exercises.

Explanation

For congenital muscular torticollis, intensive physical therapy, consisting of passive stretching, active range-of-motion exercises, and strengthening of the neck muscles, is the most important initial management strategy. It is highly effective, with resolution rates exceeding 90% if started early, typically before 6-12 months of age. Surgical release is reserved for cases that fail extensive physical therapy, usually after 1 year of age or if there are significant facial or cranial asymmetries. Observation alone is not adequate for significant contracture. Casting is rarely used. Botulinum toxin can be considered as an adjunct but is not the primary initial treatment.

Question 5778

Topic: 4. Pediatrics
A 7-year-old child sustains a Salter-Harris Type II fracture of the distal tibia. Which zone of the physis is involved in this fracture pattern?
. Germinal zone
. Proliferative zone
. Hypertrophic zone
. Zone of provisional calcification
. Epiphyseal plate cartilage

Correct Answer & Explanation

. Hypertrophic zone

Explanation

Salter-Harris Type II fractures involve a fracture line through the hypertrophic zone of the physis, extending into the metaphysis but sparing the epiphysis. The hypertrophic zone is the weakest layer of the growth plate and is typically where Salter-Harris fractures occur. The germinal and proliferative zones are spared, which is crucial for continued growth. Type I fractures are through the physis, Type III involve the epiphysis and physis, Type IV involve epiphysis, physis, and metaphysis, and Type V is a crush injury to the physis.

Question 5779

Topic: 4. Pediatrics

A 3-month-old infant is diagnosed with developmental dysplasia of the hip (DDH) after a positive Ortolani test. Radiographs show a dislocated left hip with an acetabular index of 35 degrees. What is the most appropriate initial treatment?

. Open reduction and spica cast application
. Pavlik harness
. Hip arthroscopy
. Serial casting
. Observation and repeat examination in 3 months

Correct Answer & Explanation

. Pavlik harness

Explanation

For an infant diagnosed with DDH (dislocatable hip, positive Ortolani, and radiographic evidence) at 3 months of age, the Pavlik harness is the gold standard initial treatment. It maintains the hips in flexion and abduction, allowing for gradual reduction and acetabular development. Open reduction and spica cast are reserved for cases that fail Pavlik harness or for older infants. Hip arthroscopy is not a primary treatment for DDH. Serial casting is used for clubfoot. Observation is inappropriate for a diagnosed dislocated hip.

Question 5780

Topic: 4. Pediatrics

A 2-year-old child presents with a limp, pain, and refusal to bear weight after a low-energy fall. Radiographs of the tibia and fibula are unremarkable. Examination reveals exquisite tenderness over the mid-tibia. What is the most likely diagnosis?

. Septic arthritis of the knee
. Osteosarcoma
. Toddler's fracture
. Osgood-Schlatter disease
. Stress fracture

Correct Answer & Explanation

. Toddler's fracture

Explanation

The clinical scenario of a 2-year-old with a limp and pain after a low-energy fall, refusal to bear weight, and tenderness over the mid-tibia with unremarkable initial radiographs is classic for a Toddler's fracture. This is a non-displaced spiral or oblique fracture of the distal tibia, often difficult to visualize on initial X-rays. A repeat radiograph in 10-14 days may show periosteal reaction. Septic arthritis would involve a joint. Osteosarcoma is rare in this age group and usually visible on X-ray. Osgood-Schlatter disease occurs in adolescents. Stress fractures are typically seen in older, more active children/adolescents.

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