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4. Pediatrics MCQs

Practice Set 131 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 2601

Topic: 4. Pediatrics
A 13-year-old female sustains a fracture of the anterolateral aspect of the distal tibial epiphysis following an external rotation injury to her ankle. Which of the following explains the anatomic basis for this specific fracture pattern (Tillaux fracture)?
. The anterior tibiofibular ligament is weaker than the posterior tibiofibular ligament.
. The lateral aspect of the distal tibial physis closes first.
. The medial and central aspects of the distal tibial physis close before the anterolateral aspect.
. The syndesmosis is completely ossified at this age.
. The fibula is relatively longer than the tibia during this growth phase.

Correct Answer & Explanation

. The medial and central aspects of the distal tibial physis close before the anterolateral aspect.

Explanation

The distal tibial physis closes in a predictable pattern: central, then medial, then posterior, and finally anterolateral. Because the anterolateral physis remains open the longest, an avulsion force from the anterior inferior tibiofibular ligament (AITFL) causes a Salter-Harris III fracture of this region (Tillaux fracture).

Question 2602

Topic: Pediatric Lower Extremity

A 45-year-old distance runner undergoes a surgical plantar fascia release for recalcitrant plantar fasciitis after 18 months of failed conservative management. The surgeon completely releases the entire fascial band. What is the most likely biomechanical complication of this procedure?

. Medial column overload
. Lateral column overload and cuboid pain
. Fixed equinus deformity
. Dorsal midfoot exostosis
. Progressive cavovarus deformity

Correct Answer & Explanation

. Lateral column overload and cuboid pain

Explanation

Complete release of the plantar fascia significantly decreases the longitudinal arch height and shifts peak plantar pressures laterally. This frequently results in lateral column overload and iatrogenic cuboid syndrome.

Question 2603

Topic: 4. Pediatrics
A 14-year-old boy sustains an ankle injury resulting in a Salter-Harris III fracture of the anterolateral distal tibia. Which ligament's avulsive force is primarily responsible for this specific fracture pattern?
. Anterior talofibular ligament
. Anterior inferior tibiofibular ligament
. Posterior inferior tibiofibular ligament
. Calcaneofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament

Explanation

This describes a juvenile Tillaux fracture, caused by external rotation. The central and medial portions of the distal tibial physis close first, allowing the anterior inferior tibiofibular ligament (AITFL) to avulse the anterolateral epiphysis.

Question 2604

Topic: 4. Pediatrics
Which of the following descriptions best outlines the classical radiographic appearance of a triplane fracture of the pediatric distal tibia?
. Sagittal fracture line on the AP view, coronal fracture line on the lateral view
. Coronal fracture line on the AP view, sagittal fracture line on the lateral view
. Transverse fracture line on the AP view, coronal fracture line on the lateral view
. Sagittal fracture line on the AP view, transverse fracture line on the lateral view
. Oblique fracture lines visible only on the mortise view

Correct Answer & Explanation

. Sagittal fracture line on the AP view, coronal fracture line on the lateral view

Explanation

A standard triplane fracture acts as a Salter-Harris IV equivalent. It appears as a Salter-Harris III (sagittal plane) on the anteroposterior view and as a Salter-Harris II (coronal plane) on the lateral radiograph.

Question 2605

Topic: 4. Pediatrics
A 13-year-old boy sustains a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. What is the primary mechanism and the specific deforming ligament responsible for this fracture pattern?
. Plantarflexion and inversion; Calcaneofibular ligament
. External rotation; Anterior inferior tibiofibular ligament
. Internal rotation; Posterior inferior tibiofibular ligament
. Dorsiflexion; Anterior talofibular ligament
. Eversion; Deltoid ligament

Correct Answer & Explanation

. External rotation; Anterior inferior tibiofibular ligament

Explanation

A Tillaux fracture is a pediatric transitional fracture involving the anterolateral distal tibial epiphysis. It is caused by external rotation of the foot, where the strong anterior inferior tibiofibular ligament avulses the epiphysis.

Question 2606

Topic: 4. Pediatrics

A 17-year-old rugby player sustains high-energy trauma to the anterior chest. Clinical exam shows a prominence over the medial clavicle with dyspnea. Radiographs appear to show a posterior sternoclavicular dislocation. In a patient of this age, what is the most likely true underlying pathology?

. True sternoclavicular ligamentous rupture
. Salter-Harris type I or II physeal fracture of the medial clavicle
. Costoclavicular ligament rupture without bony injury
. Fracture of the sternal manubrium
. Anterior dislocation of the first rib

Correct Answer & Explanation

. Salter-Harris type I or II physeal fracture of the medial clavicle

Explanation

The medial clavicular physis is the last growth plate in the body to fuse, often remaining open until age 25. Injuries mimicking a sternoclavicular dislocation in adolescents and young adults are typically Salter-Harris physeal fractures.

Question 2607

Topic: 4. Pediatrics
A 5-year-old boy presents with a completely displaced extension-type III supracondylar humerus fracture. His hand is pale and pulseless. Following closed reduction and percutaneous pinning in the OR, the hand immediately becomes pink and well-perfused, but the radial pulse remains unpalpable. What is the most appropriate next step?
. Immediate open vascular exploration
. Observation and close clinical monitoring
. Intraoperative angiography
. Removal of the pins and transition to open reduction
. Administration of a sympathetic nerve block

Correct Answer & Explanation

. Observation and close clinical monitoring

Explanation

In a pediatric supracondylar humerus fracture presenting with a 'pink, pulseless' hand after successful fracture reduction and stabilization, collateral circulation is typically adequate. The standard of care is observation and close clinical monitoring rather than surgical exploration.

Question 2608

Topic: 4. Pediatrics

A 3-year-old child presents with short stature, rhizomelic shortening of the limbs, and frontal bossing. This condition is typically caused by a gain-of-function mutation in FGFR3. Which zone of the physis is primarily affected?

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

Correct Answer & Explanation

. Proliferative zone

Explanation

Achondroplasia is caused by an activating mutation in the FGFR3 gene. This overactivity profoundly suppresses chondrocyte division in the proliferative zone of the physis, leading to stunted endochondral ossification.

Question 2609

Topic: 4. Pediatrics

Osteogenesis imperfecta is most commonly caused by mutations in the COL1A1 or COL1A2 genes. These mutations typically result in the substitution of which critical amino acid, disrupting the collagen triple helix?

. Proline
. Hydroxyproline
. Glycine
. Lysine
. Glutamate

Correct Answer & Explanation

. Glycine

Explanation

Type I collagen has a repeating Glycine-X-Y sequence. Mutations in osteogenesis imperfecta typically cause bulky amino acids to substitute for glycine, which normally fits into the tight center of the collagen triple helix.

Question 2610

Topic: 4. Pediatrics

A 2-year-old child presents with frequent fractures and bluish sclerae. A mutation in the COL1A1 gene is identified. Which of the following structural defects in collagen is most likely present?

. Decreased cross-linking due to lysyl oxidase deficiency
. Substitution of glycine with a bulky amino acid
. Inability to hydroxylate proline and lysine residues
. Defect in the cleavage of procollagen N- and C-terminals
. Impaired glycosylation of hydroxylysine

Correct Answer & Explanation

. Substitution of glycine with a bulky amino acid

Explanation

Osteogenesis imperfecta is most commonly caused by a genetic mutation leading to the substitution of glycine with a bulkier amino acid in the type I collagen triple helix. This prevents proper triple-helical folding and structural integrity.

Question 2611

Topic: 4. Pediatrics

An 8-year-old boy sustains a Salter-Harris Type II fracture of the distal femur. Through which specific microscopic zone of the physis does the fracture line classically propagate before exiting through the metaphysis?

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

Correct Answer & Explanation

. Reserve zone

Explanation

Salter-Harris fractures typically propagate through the zone of hypertrophy. This zone represents the mechanical weak point of the physis because it has a high ratio of cell volume to extracellular matrix.

Question 2612

Topic: 4. Pediatrics

An activating mutation in the FGFR3 gene primarily affects which zone of the physis, leading to the clinical presentation of achondroplasia?

. Reserve zone
. Proliferative zone
. Hypertrophic zone
. Primary spongiosa
. Secondary spongiosa

Correct Answer & Explanation

. Reserve zone

Explanation

Achondroplasia is caused by a gain-of-function mutation in FGFR3, which pathologically inhibits chondrocyte proliferation. Therefore, the proliferative zone of the physis is primarily affected, leading to short-limbed dwarfism.

Question 2613

Topic: 4. Pediatrics

The biological principle stating that bone will adapt its mass and architecture to the mechanical loads and stresses placed upon it is known as:

. Heuter-Volkmann principle
. Wolff's Law
. Hooke's Law
. Faraday's Law
. Perren's strain theory

Correct Answer & Explanation

. Heuter-Volkmann principle

Explanation

Wolff's Law states that healthy bone remodels in response to the mechanical stresses it experiences, becoming thicker in areas of high stress. The Heuter-Volkmann principle applies specifically to physeal growth under compression or tension.

Question 2614

Topic: 4. Pediatrics

Achondroplasia is the most common form of short-limb dwarfism. It is caused by an activating mutation in the FGFR3 gene, which predominantly inhibits chondrocyte activity in which zone of the physis?

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

Correct Answer & Explanation

. Reserve zone

Explanation

Achondroplasia results from a mutation in FGFR3 that abnormally suppresses chondrocyte proliferation in the proliferative zone of the growth plate, impairing endochondral ossification.

Question 2615

Topic: 4. Pediatrics

Which of the following specific genetic mutations is recognized as the most common underlying cause of osteogenesis imperfecta?

. Mutation in the COMP gene
. Mutation in the FGFR3 gene
. Mutation in the COL1A1 or COL1A2 genes
. Mutation in the RUNX2 transcription factor
. Mutation in the FBN1 gene

Correct Answer & Explanation

. Mutation in the COMP gene

Explanation

Osteogenesis imperfecta is predominantly caused by autosomal dominant mutations in either the COL1A1 or COL1A2 genes. These mutations lead to qualitative or quantitative defects in Type I collagen, resulting in brittle bones.

Question 2616

Topic: Pediatric Upper Extremity & Spine

A patient presents with proximal forearm pain and weakness in flexing the thumb interphalangeal joint. Compression of the median nerve at the ligament of Struthers involves an aberrant anatomical band connecting the medial epicondyle to what structure?

. Supracondylar process
. Coracoid process
. Radial tuberosity
. Olecranon
. Lateral epicondyle

Correct Answer & Explanation

. Supracondylar process

Explanation

The ligament of Struthers is an anomalous band present in about 1% of the population, connecting a bony supracondylar process on the anteromedial humerus to the medial epicondyle. It can compress both the median nerve and the brachial artery.

Question 2617

Topic: 4. Pediatrics

A 10-year-old male soccer player (Tanner stage 1) sustains a complete ACL tear and experiences recurrent giving-way episodes despite physical therapy. To minimize the risk of physeal arrest and angular deformity, which surgical technique is most appropriate?

. Standard transphyseal bone-patellar tendon-bone (BPTB) autograft
. Iliotibial band extra-articular physeal-sparing reconstruction
. Transphyseal hamstring autograft with interference screw fixation
. Tibial tubercle transfer
. High tibial opening wedge osteotomy

Correct Answer & Explanation

. Standard transphyseal bone-patellar tendon-bone (BPTB) autograft

Explanation

In prepubescent patients with substantial growth remaining (Tanner stage 1 or 2), physeal-sparing techniques, such as an iliotibial band extra-articular reconstruction (e.g., modified MacIntosh or Micheli procedure), are indicated to avoid iatrogenic physeal arrest.

Question 2618

Topic: 4. Pediatrics

A 9-year-old male (Tanner stage 1) sustains a midsubstance ACL rupture while playing soccer. He experiences giving way during daily activities. What is the most widely recommended surgical approach to minimize the risk of growth arrest?

. Transphyseal BPTB autograft reconstruction
. Standard adult-type hamstring autograft reconstruction
. Physeal-sparing all-epiphyseal reconstruction
. Extra-articular iliotibial band tenodesis alone
. Primary repair of the ACL stumps

Correct Answer & Explanation

. Transphyseal BPTB autograft reconstruction

Explanation

In prepubescent children (Tanner stages 1 and 2) with significant remaining growth, physeal-sparing techniques such as all-epiphyseal reconstruction are recommended to avoid iatrogenic physeal injury and subsequent growth arrest.

Question 2619

Topic: 4. Pediatrics

A 9-year-old prepubescent soccer player with wide-open physes sustains a complete ACL tear. Nonoperative management has failed due to recurrent instability. What is the most appropriate surgical technique to minimize the risk of limb length discrepancy and angular deformity?

. Standard trans-tibial BPTB reconstruction
. Physeal-sparing extra-articular or all-epiphyseal reconstruction
. Transtibial and transfemoral hamstring reconstruction with interference screws
. Open primary repair of the ACL with suture anchors
. Delayed reconstruction until complete skeletal maturity

Correct Answer & Explanation

. Standard trans-tibial BPTB reconstruction

Explanation

In prepubescent children with significant growth remaining (Tanner stage 1 or 2), physeal-sparing techniques (such as all-epiphyseal or extra-articular ITB reconstruction) are indicated to minimize the risk of physeal arrest. Delaying surgery in unstable knees leads to high rates of meniscal and chondral damage.

Question 2620

Topic: 4. Pediatrics

A 12-year-old elite baseball pitcher presents with a gradual onset of proximal arm pain when throwing. Radiographs demonstrate widening and irregularity of the proximal humeral physis. What is the most appropriate initial management?

. Corticosteroid injection into the subacromial space
. Physical therapy focusing on rotator cuff strengthening while continuing to pitch
. Absolute cessation of throwing for 3 months
. Open reduction and internal fixation of the physis
. In situ percutaneous pinning of the physis

Correct Answer & Explanation

. Corticosteroid injection into the subacromial space

Explanation

Little League Shoulder is a stress fracture of the proximal humeral physis caused by repetitive rotational stresses during throwing. The mainstay of treatment is absolute rest and cessation of throwing for typically 3 months to allow physeal healing.

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