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4. Pediatrics MCQs

Practice Set 151 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 3001

Topic: Pediatric Upper Extremity & Spine

A 13-year-old girl with adolescent idiopathic scoliosis (AIS) has a right thoracic curve of 55 degrees. She is Risser 0. Pulmonary function testing demonstrates a forced vital capacity (FVC) of 55% of predicted. What is the most appropriate surgical approach?

. Anterior spinal fusion
. Posterior spinal fusion
. Combined anterior and posterior spinal fusion
. Thoracoscopic anterior tethering
. Growing rod instrumentation

Correct Answer & Explanation

. Anterior spinal fusion

Explanation

Posterior spinal fusion is the standard of care for large thoracic curves in AIS. Anterior approaches are generally contraindicated in patients with diminished pulmonary function (FVC < 60% to 70% predicted) due to the risk of postoperative pulmonary decline.

Question 3002

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal female presents for scoliosis evaluation. Radiographs demonstrate a right thoracic curve of 32 degrees. Her Risser stage is 0. What is the most appropriate next step in management?

. Observation with repeat radiographs in 6 months
. Nighttime-only rigid bracing
. Full-time thoracolumbosacral orthosis (TLSO) bracing
. Posterior spinal fusion
. Anterior tethering procedure

Correct Answer & Explanation

. Observation with repeat radiographs in 6 months

Explanation

Full-time bracing with a TLSO is indicated for skeletally immature patients (Risser 0-2, premenarchal) with an idiopathic scoliosis curve between 25 and 45 degrees to halt curve progression.

Question 3003

Topic: Pediatric Upper Extremity & Spine

A 13-year-old premenarchal female (Risser 0) presents with a right thoracic adolescent idiopathic scoliosis. Standing radiographs demonstrate a primary thoracic curve of 35 degrees. What is the most appropriate management?

. Observation with repeat radiographs in 6 months
. Thoracolumbosacral orthosis (TLSO) for 16-23 hours per day
. Physical therapy and nighttime-only bending brace
. Posterior spinal fusion
. Anterior vertebral body tethering

Correct Answer & Explanation

. Observation with repeat radiographs in 6 months

Explanation

Bracing is indicated for skeletally immature patients (Risser 0-2, premenarchal) with progressive curves between 25 and 45 degrees. A TLSO worn for 16 to 23 hours daily has been proven to significantly reduce the progression of curves to surgical thresholds.

Question 3004

Topic: 4. Pediatrics



A 14-year-old adolescent sustains a twisting ankle injury. Radiographs demonstrate a Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis. What anatomical structure is responsible for the avulsion of this fracture fragment?

. Anterior talofibular ligament
. Calcaneofibular ligament
. Anterior inferior tibiofibular ligament
. Posterior inferior tibiofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior talofibular ligament

Explanation

This scenario describes a juvenile Tillaux fracture. The avulsion of the anterolateral distal tibial epiphysis is caused by tension from the anterior inferior tibiofibular ligament (AITFL) as the medial portion of the distal tibial physis closes before the lateral portion.

Question 3005

Topic: 4. Pediatrics

A 14-year-old girl twists her ankle while playing soccer. Radiographs reveal a Salter-Harris III fracture of the anterolateral distal tibia. Avulsion of this bony fragment is caused by tension from which of the following structures?

. Anterior talofibular ligament
. Calcaneofibular ligament
. Anterior inferior tibiofibular ligament
. Posterior inferior tibiofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior talofibular ligament

Explanation

The juvenile Tillaux fracture is an avulsion of the anterolateral distal tibial epiphysis by the anterior inferior tibiofibular ligament (AITFL). This occurs in adolescents because the medial aspect of the distal tibial physis closes before the lateral aspect.

Question 3006

Topic: Pediatric Lower Extremity

A 14-year-old boy presents with recurrent ankle sprains, a rigid flatfoot, and peroneal muscle spasm. Suspecting the most common type of tarsal coalition, which radiographic view is most likely to demonstrate the pathology?

. Weight-bearing AP radiograph
. Weight-bearing lateral radiograph
. 45-degree internal oblique radiograph
. Harris axial radiograph
. Canale view radiograph

Correct Answer & Explanation

. Weight-bearing AP radiograph

Explanation

Calcaneonavicular coalition is the most common tarsal coalition and is best visualized on a 45-degree internal oblique radiograph, often presenting as the "anteater nose" sign.

Question 3007

Topic: 4. Pediatrics

Which of the following zones of the normal physis (growth plate) is the primary site of cellular proliferation and is intrinsically abnormal in patients with achondroplasia?

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

Correct Answer & Explanation

. Reserve zone

Explanation

Achondroplasia is caused by an autosomal dominant gain-of-function mutation in FGFR3, which pathologically inhibits chondrocyte proliferation. This directly restricts longitudinal growth at the proliferative zone of the physis.

Question 3008

Topic: 4. Pediatrics

Type I collagen is the most abundant structural protein in the extracellular matrix of bone. Genetic mutations in Type I collagen genes (COL1A1 or COL1A2) are the primary cause of which of the following disorders?

. Osteopetrosis
. Osteogenesis imperfecta
. Achondroplasia
. Cleidocranial dysplasia
. Hypophosphatemic rickets

Correct Answer & Explanation

. Osteopetrosis

Explanation

Osteogenesis imperfecta (brittle bone disease) is most commonly caused by mutations in the COL1A1 or COL1A2 genes. This results in the production of defective or deficient Type I collagen, leading to significant skeletal fragility.

Question 3009

Topic: 4. Pediatrics

Achondroplasia is caused by a gain-of-function mutation in FGFR3. This mutation primarily limits endochondral ossification by affecting which zone of the physis?

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

Correct Answer & Explanation

. Reserve zone

Explanation

FGFR3 negatively regulates chondrocyte proliferation during endochondral ossification. A gain-of-function mutation leads to excessive inhibition of chondrocyte division, primarily affecting the proliferative zone of the physis.

Question 3010

Topic: 4. Pediatrics

A slipped capital femoral epiphysis (SCFE) typically represents a mechanical failure through which specific zone of the physis?

. Reserve zone
. Proliferative zone
. Zone of hypertrophic maturation
. Zone of provisional calcification
. Primary spongiosa

Correct Answer & Explanation

. Reserve zone

Explanation

SCFE and most Salter-Harris type I fractures occur through the hypertrophic zone of the physis. This zone lacks substantial collagen and is mechanically the weakest area.

Question 3011

Topic: Pediatric Hip

During an open reduction of a developmental dysplasia of the hip (DDH) via an anterior approach, the surgeon must tenotomize the iliopsoas. What nerve is most at risk of injury just medial to the iliopsoas muscle belly at the level of the pelvic brim?

. Obturator nerve
. Femoral nerve
. Lateral femoral cutaneous nerve
. Sciatic nerve
. Genitofemoral nerve

Correct Answer & Explanation

. Obturator nerve

Explanation

The femoral nerve lies in the groove between the iliacus and the psoas major muscles and is immediately medial to the iliopsoas tendon at the level of the joint capsule. Care must be taken not to injure it during an iliopsoas tenotomy.

Question 3012

Topic: 4. Pediatrics

A 13-year-old obese boy presents with groin pain and an obligatory external rotation of the hip with flexion. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Through which specific histologic zone of the physis does this biomechanical failure primarily occur?

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

Correct Answer & Explanation

. Reserve zone

Explanation

A slipped capital femoral epiphysis occurs primarily through the hypertrophic zone of the physis. This zone lacks the structural strength of collagen and is the weakest area under shear stress.

Question 3013

Topic: 4. Pediatrics

A 12-year-old boy presents with right hip pain and a limp. Radiographs demonstrate a slipped capital femoral epiphysis (SCFE). Through which specific zone of the growth plate does the failure primarily occur in this condition?

. Reserve zone
. Proliferative zone
. Zone of hypertrophy
. Primary spongiosa
. Secondary spongiosa

Correct Answer & Explanation

. Reserve zone

Explanation

Slipped capital femoral epiphysis (SCFE) and most Salter-Harris fractures typically occur through the zone of hypertrophy. This zone is mechanically the weakest due to the increased ratio of cell volume to extracellular matrix.

Question 3014

Topic: Pediatric Upper Extremity & Spine

A patient presents with high median nerve neuropathy causing weakness in wrist flexion, forearm pronation, and thumb IP flexion. If the site of compression is the ligament of Struthers, this anatomic structure connects the medial epicondyle to what landmark?

. Supracondylar process of the humerus
. Coronoid process of the ulna
. Radial head
. Olecranon fossa
. Medial supracondylar ridge

Correct Answer & Explanation

. Supracondylar process of the humerus

Explanation

The ligament of Struthers is an anomalous band present in about 1% of the population, connecting the supracondylar process to the medial epicondyle. Compression here causes high median neuropathy, unlike compression at the Arcade of Struthers, which affects the ulnar nerve.

Question 3015

Topic: Pediatric Hip

During percutaneous pinning of a slipped capital femoral epiphysis (SCFE), the surgeon must avoid the posterosuperior retinacular vessels to prevent osteonecrosis. These vessels are terminal branches of which artery?

. Lateral femoral circumflex artery
. Medial femoral circumflex artery
. Obturator artery
. Superior gluteal artery
. Inferior gluteal artery

Correct Answer & Explanation

. Lateral femoral circumflex artery

Explanation

The medial femoral circumflex artery (MFCA) provides the primary blood supply to the femoral head via the posterosuperior retinacular vessels. Injury to these vessels during SCFE pinning or femoral neck fracture can lead directly to avascular necrosis.

Question 3016

Topic: 4. Pediatrics

A 6-year-old child presents with a severe, displaced extension-type supracondylar humerus fracture. On examination, the ipsilateral hand is pulseless but remains pink, warm, and well-perfused. What is the most appropriate initial management?

. Immediate open vascular exploration via an anterior approach
. Closed reduction and percutaneous pinning
. CT angiography of the upper extremity
. Observation with the arm hyperflexed beyond 90 degrees
. Prophylactic volar and dorsal forearm fasciotomies

Correct Answer & Explanation

. Immediate open vascular exploration via an anterior approach

Explanation

For a pulseless but well-perfused (pink and warm) hand following a supracondylar humerus fracture, the initial step is prompt closed reduction and percutaneous pinning. Open vascular exploration is generally indicated only if the hand remains pulseless and poorly perfused (white/cold) after reduction.

Question 3017

Topic: Pediatric Upper Extremity & Spine

According to the Lenke classification for adolescent idiopathic scoliosis, which of the following radiographic criteria defines a minor curve as "structural" and necessitates its inclusion in the fusion construct?

. Cobb angle > 15 degrees on standing PA radiographs
. Apical vertebral translation > 2 cm
. Nash-Moe rotation of grade 2 or higher
. Cobb angle ≥ 25 degrees on side-bending radiographs
. Thoracic lordosis < 5 degrees

Correct Answer & Explanation

. Cobb angle > 15 degrees on standing PA radiographs

Explanation

In the Lenke classification, a minor curve is considered structural if it fails to bend out to less than 25 degrees on side-bending radiographs, or if there is a regional kyphosis of ≥ 20 degrees. Structural curves must be included in the operative fusion.

Question 3018

Topic: 4. Pediatrics

A 3-year-old child is diagnosed with congenital scoliosis secondary to a fully segmented hemivertebra at T8. Which of the following screening strategies is most critical to perform routinely in this patient due to the high rate of associated systemic anomalies?

. Renal ultrasound and total spine MRI
. Pulmonary function tests and CT of the chest
. DEXA scan and serum calcium
. Genetic testing for FGFR3 mutation
. Electromyography (EMG) of the lower extremities

Correct Answer & Explanation

. Renal ultrasound and total spine MRI

Explanation

Congenital scoliosis is highly associated with the VACTERL spectrum. Specifically, genitourinary anomalies occur in 20-30% of patients (requiring a renal ultrasound) and intraspinal anomalies like tethered cord occur in 20-40% (requiring total spine MRI).

Question 3019

Topic: Pediatric Upper Extremity & Spine

In the surgical planning for adolescent idiopathic scoliosis, a Lenke Type 1 curve is defined by which of the following structural characteristics?

. Structural proximal thoracic curve and structural main thoracic curve
. Structural thoracolumbar/lumbar curve
. Structural main thoracic curve with nonstructural proximal thoracic and thoracolumbar/lumbar curves
. Double major structural curves
. Triple major structural curves

Correct Answer & Explanation

. Structural proximal thoracic curve and structural main thoracic curve

Explanation

A Lenke Type 1 curve (Main Thoracic) dictates that the main thoracic curve is structural, while both the proximal thoracic and thoracolumbar/lumbar curves are nonstructural (they bend out to less than 25 degrees on side-bending radiographs).

Question 3020

Topic: Pediatric Upper Extremity & Spine

A 14-year-old female with adolescent idiopathic scoliosis (AIS) has a main thoracic curve of 55 degrees and a lumbar curve of 40 degrees. On side-bending films, the lumbar curve corrects to 20 degrees. The center sacral vertical line (CSVL) lies completely medial to the medial border of the apical lumbar vertebra. According to the Lenke classification, what is the correct lumbar modifier for this curve pattern?

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

Correct Answer & Explanation

. Modifier A

Explanation

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

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