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4. Pediatrics MCQs

Practice Set 129 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 2561

Topic: 4. Pediatrics

A 13-year-old girl sustains an ankle injury resulting in a juvenile Tillaux fracture. This fracture pattern is directly related to the normal closure sequence of the distal tibial physis. Which of the following describes the correct chronological sequence of distal tibial physeal closure?

. Lateral to medial
. Medial to lateral
. Central then anteromedial then posteromedial then lateral
. Central then posteromedial then anteromedial then lateral
. Peripheral to central

Correct Answer & Explanation

. Central then posteromedial then anteromedial then lateral

Explanation

The distal tibial physis closes in a predictable pattern: central, then anteromedial, then posteromedial, and finally lateral. The late open lateral physis predisposes adolescents to Tillaux fractures (avulsion by the AITFL).

Question 2562

Topic: 4. Pediatrics
A 14-year-old boy presents after an external rotation injury to his ankle. Radiographs demonstrate a triplane fracture. How does this fracture typically appear on standard anteroposterior (AP) and lateral ankle radiographs?
. AP shows Salter-Harris III and Lateral shows Salter-Harris II
. AP shows Salter-Harris II and Lateral shows Salter-Harris III
. AP shows Salter-Harris IV and Lateral shows Salter-Harris II
. AP shows Salter-Harris I and Lateral shows Salter-Harris IV
. AP shows Salter-Harris II and Lateral shows Salter-Harris IV

Correct Answer & Explanation

. AP shows Salter-Harris III and Lateral shows Salter-Harris II

Explanation

A triplane fracture typically appears as a Salter-Harris III fracture on the anteroposterior (AP) radiograph and a Salter-Harris II fracture on the lateral radiograph. It represents a true Salter-Harris IV injury occurring in three planes.

Question 2563

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from the monkey bars and sustains an extension-type Gartland III supracondylar humerus fracture. On presentation, his hand is pink but pulseless. He is unable to flex the interphalangeal joint of his thumb and the distal interphalangeal joint of his index finger. Which of the following nerves is most likely injured?
. Ulnar nerve
. Anterior interosseous nerve
. Radial 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 results in the inability to make an 'A-OK' sign due to weakness of the flexor pollicis longus and flexor digitorum profundus to the index finger.

Question 2564

Topic: Pediatric Hip

A 12-year-old boy with a BMI in the 98th percentile is diagnosed with a unilateral stable slipped capital femoral epiphysis (SCFE) and treated with in situ pinning. Prophylactic pinning of the contralateral asymptomatic hip is most strongly indicated in which of the following clinical scenarios?

. The patient is male.
. The patient is African American.
. The patient has underlying hypothyroidism.
. The patient has a slip angle greater than 50 degrees.
. The patient's physis is wide.

Correct Answer & Explanation

. The patient has underlying hypothyroidism.

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly recommended for patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) or prior radiation, as they have a very high risk of bilateral involvement.

Question 2565

Topic: Pediatric Lower Extremity

When utilizing the Ponseti method for the treatment of idiopathic clubfoot, the sequence of deformity correction is critical. Which of the following represents the correct sequential order of correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method follows the CAVE sequence: Cavus is corrected first by elevating the first ray, followed by Adductus and Varus corrected simultaneously, and Equinus is corrected last, often requiring a percutaneous Achilles tenotomy.

Question 2566

Topic: Pediatric Hip

An 8-month-old infant with developmental dysplasia of the hip (DDH) undergoes a closed reduction and spica casting. To minimize the risk of iatrogenic avascular necrosis (AVN), the hip must be positioned within the 'safe zone' of Ramsey. Which of the following best describes this optimal position?

. Extreme abduction and internal rotation
. 90 to 100 degrees of flexion and mild to moderate abduction
. Extension, adduction, and external rotation
. 120 degrees of flexion and maximal abduction
. Neutral flexion with 60 degrees of adduction

Correct Answer & Explanation

. 90 to 100 degrees of flexion and mild to moderate abduction

Explanation

The safe zone of Ramsey defines the position where the hip is reduced without excessive capsular tension. Immobilization in extreme abduction forces the femoral head against the acetabulum, severely increasing the risk of AVN. The ideal position is ~90-100 degrees of flexion and mild to moderate abduction.

Question 2567

Topic: 4. Pediatrics

A 2-year-old girl is evaluated for bilateral severe bowing of the legs. Radiographs demonstrate a metaphyseal-diaphyseal (MD) angle of 18 degrees bilaterally. What is the most appropriate initial management?

. Observation and reassurance
. Knee-ankle-foot orthosis (KAFO) bracing
. Proximal tibial osteotomies
. Hemiepiphysiodesis of the lateral proximal tibia
. Vitamin D supplementation

Correct Answer & Explanation

. Knee-ankle-foot orthosis (KAFO) bracing

Explanation

An MD angle greater than 16 degrees in a child aged 2 to 3 years is highly suggestive of infantile Blount's disease. The standard initial management for early-stage infantile Blount's disease is KAFO bracing.

Question 2568

Topic: 4. Pediatrics

A 4-year-old boy with a history of recurrent low-energy fractures presents to the clinic. Examination reveals blue sclerae and mild joint hyperlaxity. A genetic defect affecting which of the following is the most likely cause of his condition?

. Type I collagen
. Type II collagen
. Type X collagen
. Fibroblast growth factor receptor 3 (FGFR3)
. Cartilage oligomeric matrix protein (COMP)

Correct Answer & Explanation

. Type I collagen

Explanation

Osteogenesis imperfecta is a genetic disorder of connective tissue characterized by bone fragility, blue sclerae, and dentinogenesis imperfecta. It is caused by mutations in the COL1A1 or COL1A2 genes, which encode Type I collagen.

Question 2569

Topic: Pediatric Hip
When evaluating a 7-year-old child with Legg-Calvรฉ-Perthes disease, which of the following radiographic findings during the fragmentation stage is associated with the worst long-term prognosis?
. Crescent sign covering 20% of the femoral head
. Intact lateral pillar > 50% of original height
. Lateral pillar involvement leaving < 50% of the original height intact
. Mild metaphyseal cysts
. Sclerosis of the central epiphysis

Correct Answer & Explanation

. Lateral pillar involvement leaving < 50% of the original height intact

Explanation

The Herring Lateral Pillar classification during the fragmentation stage is highly prognostic. A Lateral Pillar Group C classification (where the lateral pillar is <50% of its original height) is associated with the worst outcomes, often resulting in an aspherical, incongruent hip.

Question 2570

Topic: 4. Pediatrics

A 10-year-old boy sustains a Salter-Harris II fracture of the distal femur. What is the approximate reported incidence of premature physeal closure (growth arrest) associated with this specific injury pattern at this location?

. 1%
. 5%
. 15%
. 50%
. 95%

Correct Answer & Explanation

. 50%

Explanation

Distal femur physeal fractures have an exceptionally high rate of premature physeal closure, historically reported to be up to 40% to 50%, even in low-grade (Salter-Harris I and II) injuries, due to the undulating nature of the distal femoral physis.

Question 2571

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal female with Risser stage 0 is diagnosed with adolescent idiopathic scoliosis (AIS). She has a right thoracic curve. Which of the following scenarios is the most appropriate indication to initiate treatment with a Thoracolumbosacral Orthosis (TLSO)?

. A 15-degree curve at initial presentation
. A 20-degree curve without documented progression
. A 25-degree curve with documented progression of 6 degrees over 6 months
. A 45-degree curve at initial presentation
. A 50-degree curve with pain

Correct Answer & Explanation

. A 25-degree curve with documented progression of 6 degrees over 6 months

Explanation

Bracing in AIS is indicated for growing children (Risser 0-2) with curves between 25 and 44 degrees that have documented progression (>5 degrees) or those presenting initially with curves of 30 to 39 degrees. Curves >45-50 degrees generally require surgery.

Question 2572

Topic: 4. Pediatrics
A 13-year-old girl presents with an ankle injury after an external rotation mechanism. Radiographs demonstrate a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. What ligament is directly 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 inferior tibiofibular ligament

Explanation

A Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It is an avulsion injury caused by the strong pull of the anterior inferior tibiofibular ligament (AITFL) as the medial distal tibial physis closes before the lateral side.

Question 2573

Topic: Pediatric Hip

A 12-year-old obese boy presents with severe groin pain and an inability to bear weight after a minor fall. Radiographs show a slipped capital femoral epiphysis (SCFE). According to the Loder classification, what specific clinical finding defines this slip as "unstable"?

. Slip angle > 50 degrees
. Inability to ambulate with or without crutches
. Presence of an intra-articular effusion on ultrasound
. Duration of symptoms less than 3 weeks
. Metaphyseal blanch sign on the AP radiograph

Correct Answer & Explanation

. Inability to ambulate with or without crutches

Explanation

The Loder classification functionally defines an unstable slipped capital femoral epiphysis (SCFE) as the inability to ambulate with or without crutches. Unstable SCFE has a significantly higher rate of avascular necrosis (up to 47%) compared to stable SCFE.

Question 2574

Topic: Pediatric Lower Extremity

In the Ponseti method of idiopathic clubfoot casting, what is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method corrects clubfoot deformities in the specific order of the acronym CAVE: Cavus, Adductus, Varus, and finally Equinus. The cavus is corrected first by elevating the first ray to align the forefoot with the hindfoot.

Question 2575

Topic: 4. Pediatrics

A 2-year-old girl is evaluated for severe bilateral bowing of her legs. Radiographs demonstrate an abrupt angulation and breaking of the medial proximal tibial metaphysis with a metaphyseal-diaphyseal angle of 18 degrees. What is the most appropriate initial management?

. Reassurance and annual follow-up
. Knee-ankle-foot orthoses (KAFO)
. Proximal tibial valgus osteotomy
. Guided growth with tension band plates
. Epiphysiodesis of the lateral proximal tibia

Correct Answer & Explanation

. Knee-ankle-foot orthoses (KAFO)

Explanation

In a child under 3 years with infantile Blount disease and a metaphyseal-diaphyseal angle > 16 degrees, the initial treatment is a trial of bracing with KAFOs. Surgical intervention is indicated if bracing fails or the child presents at an older age.

Question 2576

Topic: 4. Pediatrics

A 6-week-old female infant is diagnosed with a dislocated left hip that is reducible on the Ortolani maneuver. A Pavlik harness is prescribed. Excessive flexion of the hips in the harness increases the risk of which complication?

. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Inferior hip dislocation
. Acetabular dysplasia
. Knee flexion contracture

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Excessive flexion (>120 degrees) in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to femoral nerve palsy. Excessive forced abduction increases the risk of avascular necrosis of the femoral head.

Question 2577

Topic: 4. Pediatrics
A 14-year-old boy sustains a triplane fracture of the distal tibia. Which of the following correctly describes the Salter-Harris classification of the fracture lines typically seen on AP and lateral radiographs, respectively?
. AP: Salter-Harris II; Lateral: Salter-Harris III
. AP: Salter-Harris III; Lateral: Salter-Harris II
. AP: Salter-Harris I; Lateral: Salter-Harris IV
. AP: Salter-Harris IV; Lateral: Salter-Harris II
. AP: Salter-Harris II; Lateral: Salter-Harris IV

Correct Answer & Explanation

. AP: Salter-Harris III; Lateral: Salter-Harris II

Explanation

A classic triplane fracture appears as a Salter-Harris III on the AP radiograph (due to the vertical fracture through the epiphysis) and a Salter-Harris II on the lateral radiograph (due to the fracture extending through the posterior metaphysis).

Question 2578

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from monkey bars and sustains a Gartland type III supracondylar humerus fracture. On arrival, his hand is pink but the radial pulse is absent. The fracture undergoes immediate closed reduction and percutaneous pinning. Following fixation, the hand remains pink and well-perfused, but the radial pulse remains absent by Doppler. What is the most appropriate next step in management?
. Observe and admit for close neurovascular monitoring
. Immediate open exploration of the brachial artery
. Perform a CT angiogram of the upper extremity
. Remove the pins and attempt open reduction
. Consult vascular surgery for a bypass graft

Correct Answer & Explanation

. Observe and admit for close neurovascular monitoring

Explanation

A pink, pulseless hand following reduction and pinning of a supracondylar fracture indicates adequate collateral circulation. The standard of care is close observation for 24 to 48 hours rather than immediate vascular exploration.

Question 2579

Topic: Pediatric Lower Extremity

A 3-week-old infant with idiopathic clubfoot is undergoing serial casting using the Ponseti method. The deformity is corrected in a specific sequence (CAVES). Which aspect of the deformity is corrected last, frequently necessitating a minor surgical procedure?

. Cavus
. Adductus
. Varus
. Equinus
. Supination

Correct Answer & Explanation

. Equinus

Explanation

In the Ponseti method, the sequence of correction is Cavus, Adductus, Varus, and finally Equinus. Equinus correction often requires a percutaneous Achilles tenotomy as the final step before the application of the definitive cast.

Question 2580

Topic: 4. Pediatrics
A 14-year-old boy sustains an ankle injury while playing soccer. Radiographs demonstrate a Salter-Harris type III fracture of the anterolateral distal tibia epiphysis. Which of the following is the most likely mechanism of injury for this specific fracture pattern?
. Plantarflexion and inversion
. Dorsiflexion and inversion
. External rotation of the foot relative to the tibia
. Internal rotation of the foot relative to the tibia
. Direct axial loading

Correct Answer & Explanation

. External rotation of the foot relative to the tibia

Explanation

A juvenile Tillaux fracture is an avulsion of the anterolateral distal tibial epiphysis caused by the anterior inferior tibiofibular ligament (AITFL). It occurs via an external rotation mechanism during the transitional period of physeal closure.

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