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4. Pediatrics MCQs

Practice Set 170 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 3381

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy presents with a completely displaced extension-type supracondylar humerus fracture. On examination, the hand is pink and warm, but the radial pulse is absent. Capillary refill is less than 2 seconds. What is the most appropriate next step in management?

. Immediate open vascular exploration
. Closed reduction and percutaneous pinning, then reassess perfusion
. Doppler ultrasound of the brachial artery
. Angiography of the upper extremity
. Application of a long arm cast in 120 degrees of flexion

Correct Answer & Explanation

. Closed reduction and percutaneous pinning, then reassess perfusion

Explanation

The pulseless, pink hand is a well-described clinical scenario in completely displaced supracondylar humerus fractures. The most appropriate initial step is urgent closed reduction and percutaneous pinning, followed by reassessment of the vascular status.

Question 3382

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 32 presents with an acute-on-chronic stable left slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic pinning of the contralateral asymptomatic hip?

. Age less than 10 years or greater than 16 years
. Presence of an endocrine disorder such as hypothyroidism
. Severe slip angle (> 60 degrees) on the affected side
. Presentation with an unstable SCFE
. Male sex and high body mass index alone

Correct Answer & Explanation

. Presence of an endocrine disorder such as hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly indicated in patients with underlying endocrine disorders (such as hypothyroidism or renal osteodystrophy) or prior radiation therapy, as they are at a markedly increased risk of bilateral involvement.

Question 3383

Topic: Pediatric Hip

A 6-week-old girl is being treated with a Pavlik harness for developmental dysplasia of the hip. At her 2-week follow-up, she is noted to have decreased active extension of the knee on the treated side. Which of the following is the most appropriate next step?

. Abandon the harness and proceed to closed reduction and spica casting
. Adjust the anterior straps to decrease hip flexion
. Adjust the posterior straps to increase hip abduction
. Obtain an MRI of the lumbar spine
. Refer for electromyography (EMG)

Correct Answer & Explanation

. Adjust the anterior straps to decrease hip flexion

Explanation

Decreased active knee extension indicates a femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness. Management consists of adjusting the anterior straps to decrease hip flexion or temporarily removing the harness if symptoms persist.

Question 3384

Topic: 4. Pediatrics
A 13-year-old girl sustains an ankle injury. Radiographs demonstrate a Salter-Harris III fracture of the anterolateral distal tibia. Which of the following describes the typical sequence of physeal closure in the distal tibia that predisposes to this specific injury pattern?
. Central, then medial, then lateral
. Lateral, then central, then medial
. Medial, then lateral, then central
. Central, then lateral, then medial
. Lateral, then medial, then central

Correct Answer & Explanation

. Central, then lateral, then medial

Explanation

The distal tibial physis closes asymmetrically: first centrally, then posteromedially, then anteromedially, and lastly laterally. This leaves the anterolateral portion vulnerable to avulsion by the anterior inferior tibiofibular ligament (Tillaux fracture).

Question 3385

Topic: 4. Pediatrics
A 3-year-old boy treated successfully in infancy for idiopathic clubfoot with the Ponseti method presents with recurrent dynamic supination of the foot during the swing phase of gait. Passive range of motion of the foot is normal. What is the most appropriate surgical management?
. Achilles tendon lengthening
. Posteromedial soft tissue release
. Split anterior tibial tendon transfer (SPLATT)
. Transfer of the entire anterior tibial tendon to the lateral cuneiform
. First metatarsal opening wedge osteotomy

Correct Answer & Explanation

. Transfer of the entire anterior tibial tendon to the lateral cuneiform

Explanation

Dynamic supination in a relapsed idiopathic clubfoot treated by the Ponseti method is best managed by transferring the entire anterior tibial tendon to the third (lateral) cuneiform. A SPLATT is typically reserved for spastic conditions such as cerebral palsy.

Question 3386

Topic: Pediatric Hip

A 6-week-old female is undergoing treatment with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 1-week follow-up, the parents report she has stopped kicking her left leg. On examination, there is decreased active extension of the left knee, but normal ankle movements. What is the most appropriate next step in management?

. Perform a formal ultrasound of the hip
. Adjust the anterior straps to increase hip flexion
. Temporarily discontinue the harness and observe
. Switch to a rigid hip spica cast
. Refer for nerve conduction studies

Correct Answer & Explanation

. Temporarily discontinue the harness and observe

Explanation

Decreased active knee extension indicates a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The harness should be temporarily removed until nerve function recovers.

Question 3387

Topic: Pediatric Lower Extremity

A 2-week-old infant presents with idiopathic clubfoot. The Ponseti method is initiated. What is the correct sequence of deformity correction during serial casting?

. Cavus, Adductus, Varus, Equinus
. Adductus, Varus, Cavus, Equinus
. Cavus, Varus, Adductus, Equinus
. Equinus, Cavus, Adductus, Varus
. Varus, Cavus, Equinus, Adductus

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method corrects the deformities in a specific sequence summarized by the acronym CAVE: Cavus, Adductus, Varus, and finally Equinus.

Question 3388

Topic: Pediatric Hip

A 12-year-old boy presents with left knee pain and a limp. Radiographs confirm a stable left slipped capital femoral epiphysis (SCFE). Which of the following is the most accepted indication for prophylactic pinning of the contralateral asymptomatic hip?

. Patient age older than 14 years
. Presentation with a stable SCFE on the affected side
. Presence of an underlying endocrine disorder
. Male sex
. Body mass index greater than 95th percentile

Correct Answer & Explanation

. Presence of an underlying endocrine disorder

Explanation

Prophylactic pinning of the contralateral hip is strongly considered in patients with underlying endocrine disorders, renal failure, or who are very young, due to a high risk of bilateral involvement.

Question 3389

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains an extension-type Gartland III supracondylar humerus fracture. Examination reveals weakness in flexing the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. Which nerve is most likely injured?
. Radial nerve
. Ulnar nerve
. Anterior interosseous nerve
. Posterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. Injury presents with an inability to form the "A-OK" sign.

Question 3390

Topic: 4. Pediatrics

In a child with Legg-Calve-Perthes disease, which of the following radiographic findings during the fragmentation stage is considered a "head-at-risk" sign indicating a poorer prognosis?

. Coxa magna
. Gage sign
. Medial subluxation of the femoral head
. Increased medial joint space
. Enlargement of the teardrop

Correct Answer & Explanation

. Gage sign

Explanation

Catterall's "head-at-risk" signs include the Gage sign (V-shaped radiolucency in the lateral epiphysis/metaphysis), lateral calcification, lateral subluxation, and horizontal physis.

Question 3391

Topic: Pediatric Hip

An 8-month-old female presents with an untreated developmental dysplasia of the hip (DDH) with a dislocated left hip. What is the most appropriate initial management?

. Pavlik harness
. Rigid abduction orthosis
. Closed reduction and spica casting
. Open reduction and spica casting
. Open reduction and femoral shortening osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

For DDH presenting between 6 and 18 months of age, closed reduction and spica casting is the initial treatment of choice. The Pavlik harness is typically ineffective after 6 months of age.

Question 3392

Topic: 4. Pediatrics
According to established hip surveillance guidelines for children with cerebral palsy, which Gross Motor Function Classification System (GMFCS) level is associated with the highest risk of hip displacement?
. Level I
. Level II
. Level III
. Level IV
. Level V

Correct Answer & Explanation

. Level V

Explanation

The risk of hip displacement in cerebral palsy increases with clinical severity. GMFCS Level V has the highest risk, with up to a 90% chance of progressive hip subluxation.

Question 3393

Topic: 4. Pediatrics
A 14-year-old girl sustains an ankle injury. Radiographs reveal a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. What is the mechanism of this injury?
. Supination-internal rotation
. Pronation-abduction
. External rotation of the foot relative to the leg
. Axial load and hyperplantarflexion
. Direct blow to the anterior ankle

Correct Answer & Explanation

. External rotation of the foot relative to the leg

Explanation

A Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It is caused by an external rotation force that avulses the bone via the anterior inferior tibiofibular ligament (AITFL).

Question 3394

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal girl presents with adolescent idiopathic scoliosis. Her primary thoracic curve measures 25 degrees. Her Risser stage is 0. What is her approximate risk of curve progression to greater than 50 degrees?

. 10%
. 20%
. 40%
. 68%
. 90%

Correct Answer & Explanation

. 68%

Explanation

In a patient with Risser stage 0-1 and a curve of 20 to 29 degrees, the risk of curve progression is approximately 68%. Bracing is strongly indicated in this scenario.

Question 3395

Topic: 4. Pediatrics

Osteogenesis imperfecta is most commonly caused by an autosomal dominant mutation affecting which of the following?

. Fibroblast growth factor receptor 3 (FGFR3)
. Type I collagen (COL1A1 or COL1A2)
. Type II collagen (COL2A1)
. Type X collagen (COL10A1)
. Core binding factor alpha 1 (CBFA1 / RUNX2)

Correct Answer & Explanation

. Type I collagen (COL1A1 or COL1A2)

Explanation

Osteogenesis imperfecta is primarily caused by defects in Type I collagen due to mutations in the COL1A1 or COL1A2 genes, leading to bone fragility.

Question 3396

Topic: 4. Pediatrics

A 3-year-old boy presents with progressive bilateral genu varum. Radiographs reveal an increased metaphyseal-diaphyseal angle (Drennan angle) of 18 degrees and medial metaphyseal beaking. What is the most likely diagnosis?

. Physiologic bowing
. Infantile Blount disease
. Achondroplasia
. Rickets
. Osteogenesis imperfecta

Correct Answer & Explanation

. Infantile Blount disease

Explanation

A metaphyseal-diaphyseal angle greater than 16 degrees, combined with medial metaphyseal beaking in a young child, is highly predictive of infantile Blount disease rather than physiologic bowing.

Question 3397

Topic: 4. Pediatrics

Children with achondroplasia are at highest risk for which of the following life-threatening neurologic complications during infancy?

. Syringomyelia
. Tethered cord syndrome
. Foramen magnum stenosis with cervicomedullary compression
. Severe lumbar spinal stenosis
. Atlantoaxial instability

Correct Answer & Explanation

. Foramen magnum stenosis with cervicomedullary compression

Explanation

Infants with achondroplasia have a narrow foramen magnum, predisposing them to cervicomedullary compression. This can lead to central apnea and sudden death if not decompressed.

Question 3398

Topic: 4. Pediatrics

An 18-month-old girl presents with a limp. Pelvic radiographs reveal a completely dislocated left hip with an acetabular index of 42 degrees. She has had no prior treatment. What is the most appropriate management plan?

. Closed reduction and spica casting
. Pavlik harness application
. Open reduction and capsulorrhaphy
. Open reduction and pelvic osteotomy
. Femoral varus derotational osteotomy alone

Correct Answer & Explanation

. Open reduction and pelvic osteotomy

Explanation

In a child older than 18 months with a completely dislocated hip and significant acetabular dysplasia (acetabular index >40 degrees), an open reduction combined with a pelvic osteotomy is typically required. Closed reduction has a high failure rate at this age due to soft tissue interposition and fixed bony deformity.

Question 3399

Topic: Pediatric Hip

A 13-year-old obese boy presents to the emergency department unable to bear weight on his right leg after a minor slip. He reports a 3-month history of mild right knee pain. Examination shows the right hip resting in external rotation. Which of the following complications is most highly associated with this acute presentation?

. Chondrolysis
. Avascular necrosis
. Femoroacetabular impingement
. Premature osteoarthritis
. Leg length discrepancy

Correct Answer & Explanation

. Avascular necrosis

Explanation

This patient has an unstable slipped capital femoral epiphysis (SCFE), defined by the inability to bear weight. Unstable SCFE carries a significantly higher risk of avascular necrosis (up to 47%) compared to stable SCFE.

Question 3400

Topic: Pediatric Lower Extremity
A 4-year-old boy treated successfully in infancy for idiopathic clubfoot with the Ponseti method presents with an abnormal gait. Examination reveals dynamic supination of the foot during the swing phase of gait, with no fixed rigid deformities. What is the treatment of choice?
. Repeat Achilles tenotomy
. Complete transfer of the tibialis anterior tendon to the lateral cuneiform
. Split anterior tibial tendon transfer (SPLATT)
. Extensive posteromedial soft tissue release
. Calcaneocuboid fusion

Correct Answer & Explanation

. Complete transfer of the tibialis anterior tendon to the lateral cuneiform

Explanation

Dynamic supination in a relapsed Ponseti-treated clubfoot without rigid deformity is best treated with a complete transfer of the tibialis anterior tendon to the lateral cuneiform. A split transfer is less effective for this specific relapse pattern.

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