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4. Pediatrics MCQs

Practice Set 168 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 3341

Topic: Pediatric Lower Extremity

A 4-year-old boy who was successfully treated for idiopathic clubfoot as an infant using the Ponseti method presents with a dynamic supination deformity of the foot during the swing phase of gait. His ankles have 15 degrees of passive dorsiflexion. What is the treatment of choice?

. Repeat serial casting
. Tibialis anterior tendon transfer to the lateral cuneiform
. Achilles tendon lengthening
. Split tibialis posterior tendon transfer
. Triple arthrodesis

Correct Answer & Explanation

. Tibialis anterior tendon transfer to the lateral cuneiform

Explanation

Dynamic supination during gait in a previously corrected clubfoot is a classic sign of relapse caused by an overpowering tibialis anterior. Provided there is adequate ankle dorsiflexion, a full tibialis anterior tendon transfer to the lateral cuneiform is the treatment of choice.

Question 3342

Topic: 4. Pediatrics
A 13-year-old girl sustains a Salter-Harris III fracture of the anterolateral distal tibia. Which of the following ligaments is responsible for the avulsion of this specific fracture fragment?
. Anterior talofibular ligament
. Calcaneofibular ligament
. Anterior inferior tibiofibular ligament
. Posterior inferior tibiofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It occurs due to avulsion by the anterior inferior tibiofibular ligament (AITFL) during an external rotation injury as the medial physis closes before the lateral physis.

Question 3343

Topic: 4. Pediatrics

An infant with achondroplasia presents with hypotonia, apnea, and hyperreflexia. MRI of the cervicomedullary junction confirms severe stenosis at the foramen magnum. Which underlying genetic mutation is responsible for this patient's syndrome?

. COL1A1
. FGFR3
. COMP
. RUNX2
. SOX9

Correct Answer & Explanation

. FGFR3

Explanation

Achondroplasia is caused by a gain-of-function mutation in the FGFR3 gene. Severe foramen magnum stenosis can lead to cervicomedullary compression, causing central apnea and sudden death, which necessitates urgent surgical decompression.

Question 3344

Topic: 4. Pediatrics

A 6-year-old child with spastic quadriplegic cerebral palsy is found on routine surveillance screening to have a hip migration percentage of 45%. The hip is painful and abduction is limited to 15 degrees. What is the most appropriate management?

. Adductor tenotomy alone
. Botulinum toxin A injection to the adductors
. Varus derotational osteotomy (VDRO) with or without pelvic osteotomy
. Total hip arthroplasty
. Observation and repeat radiographs in 6 months

Correct Answer & Explanation

. Varus derotational osteotomy (VDRO) with or without pelvic osteotomy

Explanation

In a child with cerebral palsy, a hip migration percentage greater than 30-40% with clinical symptoms (pain, limited abduction) indicates progressive subluxation. Bony reconstruction with a VDRO, and often a concomitant pelvic osteotomy, is required to stabilize the hip.

Question 3345

Topic: 4. Pediatrics
A 4-year-old girl is diagnosed with infantile Blount disease. Radiographs show a Langenskiöld stage IV lesion with a distinct osseous bar forming across the medial physis. What is the most appropriate treatment?
. Observation
. Knee-ankle-foot orthosis (KAFO) bracing
. Proximal tibial osteotomy with overcorrection into valgus
. Physeal bar excision and proximal tibial osteotomy
. Epiphysiodesis of the lateral proximal tibia

Correct Answer & Explanation

. Physeal bar excision and proximal tibial osteotomy

Explanation

Langenskiöld stage IV infantile Blount disease is characterized by an osseous bridge across the medial proximal tibial physis. Treatment requires excision of the physeal bar to allow growth, combined with a proximal tibial valgus osteotomy to correct the mechanical axis.

Question 3346

Topic: 4. Pediatrics

A 2-year-old boy presents with anterolateral bowing of the tibia and an impending fracture. Which of the following systemic conditions is most commonly associated with this presentation?

. Neurofibromatosis type 1
. Osteogenesis imperfecta
. Cleidocranial dysplasia
. Marfan syndrome
. Ehlers-Danlos syndrome

Correct Answer & Explanation

. Neurofibromatosis type 1

Explanation

Anterolateral bowing of the tibia is highly associated with congenital pseudarthrosis of the tibia (CPT). Approximately 50% of patients with CPT have a concurrent diagnosis of Neurofibromatosis type 1 (NF1).

Question 3347

Topic: 4. Pediatrics

A 14-year-old elite baseball pitcher presents with vague anterior shoulder pain that worsens with throwing. Radiographs demonstrate widening and irregularity of the proximal humeral physis. What is the first-line treatment?

. Arthroscopic SLAP repair
. Proximal humerus epiphysiodesis
. Absolute rest from throwing for 3 months followed by physical therapy
. Corticosteroid injection into the subacromial space
. Open reduction and internal fixation of the physis

Correct Answer & Explanation

. Absolute rest from throwing for 3 months followed by physical therapy

Explanation

Little Leaguer's shoulder is an overuse injury resulting in epiphysiolysis of the proximal humerus. Treatment consists of complete rest from throwing (typically 3 months) to allow physeal healing, followed by a gradual return-to-throwing program.

Question 3348

Topic: Pediatric Hip
In a patient diagnosed with Legg-Calvé-Perthes disease, which of the following is considered the most significant prognostic factor for long-term hip joint congruency and function?
. Gender
. Age at onset of symptoms
. Body mass index (BMI)
. Bilateral involvement
. Presence of a positive Trendelenburg sign

Correct Answer & Explanation

. Age at onset of symptoms

Explanation

The age at the onset of Legg-Calvé-Perthes disease is the most reliable prognostic indicator. Children who develop the disease before age 6 to 8 generally have a much better capacity for remodeling and superior long-term outcomes than older children.

Question 3349

Topic: Pediatric Hip

A 13-year-old male presents with acute thigh pain and inability to bear weight after a minor fall. He had mild groin pain for 3 months prior. Radiographs confirm a displaced slipped capital femoral epiphysis (SCFE). He undergoes urgent in-situ pinning. Which of the following factors is most predictive of developing avascular necrosis (AVN) in this patient?

. Degree of epiphyseal slip
. Patient age at presentation
. Duration of prodromal symptoms
. Instability (inability to bear weight)
. Female sex

Correct Answer & Explanation

. Instability (inability to bear weight)

Explanation

Instability, defined by Loder as the inability to bear weight even with crutches, is the most significant risk factor for AVN in SCFE, with rates up to 47% compared to near 0% in stable slips.

Question 3350

Topic: Pediatric Hip

A 5-month-old female has been treated in a Pavlik harness for developmental dysplasia of the hip (DDH) for 4 weeks. A follow-up ultrasound demonstrates the femoral head remains dislocated out of the acetabulum. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 4 weeks
. Transition to an abduction orthosis (e.g., rigid brace)
. Discontinue the harness and proceed with closed reduction and spica casting
. Perform an immediate open reduction and femoral shortening osteotomy
. Switch to double-diapering technique

Correct Answer & Explanation

. Discontinue the harness and proceed with closed reduction and spica casting

Explanation

Prolonged use of a Pavlik harness in a persistently dislocated hip increases the risk of 'Pavlik harness disease' (posterior acetabular wear). If reduction is not achieved within 3-4 weeks, the harness should be abandoned for closed reduction and spica casting.

Question 3351

Topic: 4. Pediatrics

An infant is born with an idiopathic congenital talipes equinovarus (clubfoot). The treating orthopedic surgeon initiates the Ponseti method of serial casting. According to this method, which component of the deformity must be corrected first?

. Hindfoot equinus
. Hindfoot varus
. Midfoot supination
. Forefoot cavus
. Forefoot adduction

Correct Answer & Explanation

. Forefoot cavus

Explanation

In the Ponseti method, the first step is correcting the forefoot cavus. This is achieved by elevating the first ray to align the forefoot with the hindfoot, before abducting the foot to correct adduction and varus.

Question 3352

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy falls from monkey bars and sustains a completely displaced, extension-type supracondylar fracture of the humerus. On examination, the hand is pink and warm, but the radial pulse is non-palpable. What is the most appropriate initial management?

. Immediate open exploration of the brachial artery
. Closed reduction and percutaneous pinning
. CT angiography of the upper extremity
. Splinting in 90 degrees of flexion and observation
. Application of a long arm cast in full extension

Correct Answer & Explanation

. Closed reduction and percutaneous pinning

Explanation

For a pulseless but well-perfused (pink) hand following a supracondylar humerus fracture, the standard of care is urgent closed reduction and percutaneous pinning. The pulse frequently returns after the fracture is anatomically reduced.

Question 3353

Topic: 4. Pediatrics

A 7-year-old boy is diagnosed with Legg-Calve-Perthes disease. Radiographs show fragmentation of the femoral head. Which of the following radiographic findings is considered a 'head-at-risk' sign indicating a poorer prognosis?

. Sclerosis of the central epiphysis
. Lateral calcification of the epiphysis
. Narrowing of the medial joint space
. Subchondral radiolucent line (Crescent sign)
. Medial subluxation of the femoral head

Correct Answer & Explanation

. Lateral calcification of the epiphysis

Explanation

Catterall's 'head-at-risk' signs include lateral subluxation of the femoral head, Gage sign, calcification lateral to the epiphysis, metaphyseal cysts, and a horizontal physis. These signs portend a poorer prognosis and hinge abduction.

Question 3354

Topic: Pediatric Hip

A 12-year-old girl is diagnosed with a unilateral slipped capital femoral epiphysis (SCFE). Which of the following underlying conditions represents the strongest indication for prophylactic in-situ pinning of the contralateral, asymptomatic hip?

. Obesity (>95th percentile BMI)
. Trisomy 21
. Renal osteodystrophy
. Type 1 diabetes mellitus
. Developmental dysplasia of the hip

Correct Answer & Explanation

. Renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip is strongly indicated in patients with underlying endocrinopathies or metabolic disorders, such as renal osteodystrophy or hypothyroidism, due to the high risk (up to 100%) of bilateral involvement.

Question 3355

Topic: 4. Pediatrics
A 14-year-old male sustains an ankle injury while playing basketball. Radiographs reveal a Triplane fracture of the distal tibia. Which of the following accurately describes the Salter-Harris (SH) fracture patterns typically seen on standard anteroposterior (AP) and lateral ankle radiographs?
. AP: SH III; Lateral: SH II
. AP: SH II; Lateral: SH III
. AP: SH IV; Lateral: SH II
. AP: SH II; Lateral: SH IV
. AP: SH III; Lateral: SH III

Correct Answer & Explanation

. AP: SH III; Lateral: SH II

Explanation

A Triplane fracture is a multiplanar injury that typically appears as a Salter-Harris III fracture on the AP radiograph (vertical fracture through the epiphysis) and a Salter-Harris II fracture on the lateral radiograph (posterior metaphyseal fragment).

Question 3356

Topic: Pediatric Hip

A 12-year-old boy presents with a 2-day history of severe left hip pain and is unable to bear weight. Radiographs demonstrate a left slipped capital femoral epiphysis (SCFE). He undergoes urgent in situ pinning. Which of the following factors most strongly correlates with the development of avascular necrosis in this patient?

. Number of screws used for fixation
. Timing of surgery exceeding 48 hours
. Inability to bear weight prior to surgery
. Concomitant endocrine disorder
. Open triradiate cartilage

Correct Answer & Explanation

. Inability to bear weight prior to surgery

Explanation

Unstable SCFE, defined clinically by the inability to bear weight even with crutches, is the most significant risk factor for AVN, with rates up to 47%.

Question 3357

Topic: Pediatric Hip

A 4-month-old female is undergoing treatment with a Pavlik harness for developmental dysplasia of the left hip. During a follow-up visit, the mother reports the infant has stopped moving the left leg. Examination reveals decreased active extension of the left knee, but sensation and perfusion are intact. What is the most appropriate next step in management?

. Obtain an MRI of the lumbar spine
. Switch to a rigid hip spica cast
. Release the anterior straps of the harness
. Release the posterior straps of the harness
. Perform an immediate open reduction

Correct Answer & Explanation

. Release the anterior straps of the harness

Explanation

The clinical picture describes femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. Management requires loosening the anterior straps or discontinuing the harness temporarily to allow nerve recovery.

Question 3358

Topic: Pediatric Hip

A 13-year-old obese boy presents with acute-on-chronic left hip pain and an inability to bear weight. Radiographs demonstrate a slipped capital femoral epiphysis (SCFE), and he is classified as having an unstable slip. What is the primary theoretical advantage of performing an urgent open reduction and capsulotomy (e.g., modified Dunn procedure) rather than in situ pinning?

. To decrease the risk of chondrolysis
. To reduce the risk of avascular necrosis (AVN)
. To prevent contralateral slip
. To restore limb length
. To avoid hardware failure

Correct Answer & Explanation

. To reduce the risk of avascular necrosis (AVN)

Explanation

Unstable SCFE has a high risk of AVN. Open reduction with capsulotomy decompresses the joint hematoma and anatomically aligns the epiphysis without forceful manipulation, theoretically lowering AVN risk.

Question 3359

Topic: Pediatric Upper Extremity & Spine

A 6-year-old girl sustains a severely displaced extension-type supracondylar humerus fracture. After closed reduction and percutaneous pinning in the operating room, her hand is pink and well-perfused, but the radial pulse remains non-palpable. A biphasic Doppler signal is present at the wrist. What is the most appropriate management?

. Immediate exploration of the brachial artery
. Observation and admission for close neurovascular checks
. Angiography of the upper extremity
. Removal of the pins and open reduction
. Administration of intravenous heparin

Correct Answer & Explanation

. Observation and admission for close neurovascular checks

Explanation

A 'pink, pulseless' hand after reduction and pinning of a supracondylar fracture with good capillary refill and Doppler signals should be observed closely. Vascular exploration is indicated only if the hand becomes pale and poorly perfused (white and pulseless).

Question 3360

Topic: Pediatric Lower Extremity
A 4-year-old boy treated successfully for idiopathic clubfoot as an infant with the Ponseti method presents with a relapsed deformity. He walks with a dynamic supination of the foot during the swing phase of gait. His foot is completely passively correctable. What is the most appropriate surgical intervention?
. Split anterior tibial tendon transfer (SPLATT)
. Whole anterior tibial tendon transfer to the lateral cuneiform
. Achilles tendon lengthening alone
. Posterior medial release
. Calcaneal sliding osteotomy

Correct Answer & Explanation

. Whole anterior tibial tendon transfer to the lateral cuneiform

Explanation

Dynamic supination in a relapsed clubfoot that is passively correctable is treated with transferring the entire tibialis anterior tendon to the lateral cuneiform. This rebalances the foot and prevents further relapse.

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