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4. Pediatrics MCQs

Practice Set 134 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 2661

Topic: Pediatric Upper Extremity & Spine

A 12-year-old girl presents with adolescent idiopathic scoliosis. She is pre-menarchal. Her Risser sign is 1. Radiographs show a right thoracic curve of 34 degrees. What is the most widely accepted standard of care?

. Observation only
. Physical therapy with the Schroth method as monotherapy
. Full-time wear of a thoracolumbosacral orthosis (TLSO)
. Nighttime-only bending brace
. Posterior spinal fusion

Correct Answer & Explanation

. Observation only

Explanation

Bracing (typically full-time TLSO) is indicated for skeletally immature patients (Risser 0-2) with curves between 25 and 45 degrees. The goal of bracing is to halt progression, not to correct the curve.

Question 2662

Topic: Pediatric Hip

During open reduction for developmental dysplasia of the hip (DDH) through an anterior approach, several anatomic structures can block concentric reduction. Which structure typically causes the 'hourglass' constriction of the joint capsule?

. Transverse acetabular ligament
. Ligamentum teres
. Inverted limbus
. Iliopsoas tendon
. Pulvinar

Correct Answer & Explanation

. Transverse acetabular ligament

Explanation

The iliopsoas tendon crosses the anterior capsule and compresses it, creating an 'hourglass' shape that acts as a primary extra-articular block to reduction. This tendon must be released during an anterior open reduction.

Question 2663

Topic: Pediatric Hip

When interpreting an infant hip ultrasound for DDH using the Graf method, the alpha angle is measured. What does the alpha angle specifically quantify?

. The cartilaginous roof coverage
. The bony roof of the acetabulum
. The degree of femoral head lateralization
. The sphericity of the femoral head
. The version of the femoral neck

Correct Answer & Explanation

. The cartilaginous roof coverage

Explanation

The alpha angle in the Graf classification measures the bony roof of the acetabulum. An alpha angle greater than or equal to 60 degrees is considered normal (Type I).

Question 2664

Topic: 4. Pediatrics
A 13-year-old girl presents with ankle pain after twisting her leg. Radiographs reveal a Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis (Tillaux fracture). What is the pathomechanics of this injury?
. Avulsion by the anterior inferior tibiofibular ligament (AITFL) due to external rotation
. Avulsion by the posterior inferior tibiofibular ligament (PITFL) due to internal rotation
. Impaction from the talus due to forced dorsiflexion
. Avulsion by the deltoid ligament due to eversion
. Direct axial loading

Correct Answer & Explanation

. Avulsion by the anterior inferior tibiofibular ligament (AITFL) due to external rotation

Explanation

A juvenile Tillaux fracture is an avulsion of the anterolateral distal tibial epiphysis caused by tension on the anterior inferior tibiofibular ligament (AITFL) during an external rotation injury. It occurs in adolescents because the medial physis closes before the lateral physis.

Question 2665

Topic: Pediatric Upper Extremity & Spine

A 13-year-old boy with adolescent idiopathic scoliosis presents with an atypical curve pattern (a sharp left-sided thoracic curve). He also reports mild headaches. Which of the following is the most appropriate next step in evaluating this patient?

. Perform a CT scan of the chest
. Obtain an MRI of the entire neuraxis
. Schedule immediate posterior spinal fusion
. Measure leg length discrepancy with scanograms
. Prescribe a nighttime brace

Correct Answer & Explanation

. Perform a CT scan of the chest

Explanation

Atypical curve patterns, such as a left thoracic curve in AIS, are considered 'red flags' for underlying intraspinal pathology (e.g., syringomyelia, Chiari malformation, tethered cord). An MRI of the entire neuraxis is mandatory to rule out these anomalies.

Question 2666

Topic: 4. Pediatrics

Which of the following positions during spica casting for DDH places the infant at the highest risk for developing avascular necrosis of the femoral head?

. Flexion of 100 degrees and abduction of 40 degrees
. Flexion of 90 degrees and adduction of 0 degrees
. Flexion of 120 degrees and abduction of 70 degrees (frog-leg position)
. Extension of 0 degrees and abduction of 30 degrees
. Flexion of 45 degrees and internal rotation of 20 degrees

Correct Answer & Explanation

. Flexion of 100 degrees and abduction of 40 degrees

Explanation

Extreme abduction (the 'frog-leg' position) in a spica cast dramatically increases the pressure on the medial circumflex femoral artery, leading to a high rate of avascular necrosis. The safe zone requires moderating abduction to 40-50 degrees.

Question 2667

Topic: 4. Pediatrics
A 14-year-old boy sustains a triplane fracture of the distal tibia. Radiographically, the fracture appears as a Salter-Harris type III fracture on the anteroposterior (AP) view. What does it resemble on the lateral view?
. Salter-Harris type I
. Salter-Harris type II
. Salter-Harris type III
. Salter-Harris type IV
. Salter-Harris type V

Correct Answer & Explanation

. Salter-Harris type II

Explanation

A triplane fracture is a transitional fracture that acts as a Salter-Harris IV equivalent in 3D. Radiographically, it appears as a Salter-Harris III on the AP view and a Salter-Harris II on the lateral view.

Question 2668

Topic: Pediatric Hip

During a Pemberton pericapsular osteotomy for DDH, the osteotomy cut is directed toward and hinges on which of the following structures?

. Sacroiliac joint
. Symphysis pubis
. Ischial spine
. Triradiate cartilage
. Greater sciatic notch

Correct Answer & Explanation

. Sacroiliac joint

Explanation

The Pemberton osteotomy is an incomplete pericapsular pelvic osteotomy that hinges on the flexible triradiate cartilage. It relies on the plasticity of this cartilage to allow the acetabular roof to be rotated downward, thus improving coverage and decreasing acetabular volume.

Question 2669

Topic: Pediatric Hip

A 2-month-old infant is diagnosed with developmental dysplasia of the hip (DDH). In which of the following scenarios is the use of a Pavlik harness absolutely contraindicated?

. Bilateral hip dislocation
. Alpha angle of 45 degrees on ultrasound
. Teratologic hip dislocation associated with arthrogryposis
. Positive Ortolani sign on examination
. Failure of previous double-diapering therapy

Correct Answer & Explanation

. Bilateral hip dislocation

Explanation

The Pavlik harness relies on active infant motion to achieve and maintain reduction. It is contraindicated in teratologic dislocations, such as those associated with arthrogryposis or spina bifida, where muscle imbalance and stiffness prevent successful reduction.

Question 2670

Topic: Pediatric Upper Extremity & Spine

A 13-year-old girl with adolescent idiopathic scoliosis (AIS) presents for evaluation. Her menarche was 6 months ago. Radiographs reveal a right thoracic curve of 35 degrees and a Risser stage of 0. What is the most appropriate management?

. Observation with radiographs in 6 months
. Nighttime bending brace alone
. Full-time thoracolumbosacral orthosis (TLSO) bracing
. Posterior spinal fusion
. Anterior spinal tethering

Correct Answer & Explanation

. Observation with radiographs in 6 months

Explanation

Full-time bracing is indicated for skeletally immature patients (Risser 0-2) with progressive curves between 25 and 45 degrees. At 35 degrees with significant remaining growth potential, a TLSO is the standard of care to prevent curve progression.

Question 2671

Topic: Pediatric Upper Extremity & Spine

A 5-year-old boy sustains a severe extension-type supracondylar humerus fracture. On presentation, his hand is warm and pink, but the radial pulse is not palpable. After closed reduction and percutaneous pinning, the hand remains well-perfused with an oxygen saturation of 99%, but the pulse remains non-palpable. What is the next best step in management?

. Immediate exploration of the brachial artery
. Fasciotomy of the forearm
. Observation and hospital admission for close monitoring
. Removal of the pins and open reduction
. CT angiography of the upper extremity

Correct Answer & Explanation

. Immediate exploration of the brachial artery

Explanation

A pulseless but well-perfused (pink) hand after reduction and pinning of a supracondylar fracture should be closely observed. Collateral circulation is typically adequate, and the pulse often returns over time; surgical exploration is reserved for a pulseless, pale, and poorly perfused hand.

Question 2672

Topic: 4. Pediatrics
A 14-year-old boy sustains a juvenile Tillaux fracture of the ankle. What is the characteristic mechanism of injury for this fracture pattern?
. Internal rotation of the foot relative to the tibia
. External rotation of the foot relative to the tibia
. Pure hyper-plantarflexion
. Axial loading with a valgus force
. Direct impaction to the anterior ankle joint

Correct Answer & Explanation

. External rotation of the foot relative to the tibia

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. It is caused by an external rotation force that avulses the bony fragment via the anterior inferior tibiofibular ligament as the medial physis has already fused.

Question 2673

Topic: 4. Pediatrics
A 13-year-old girl sustains a twisting injury to her ankle. Radiographs reveal a triplane fracture. Which of the following best describes the typical Salter-Harris classification appearances on orthogonal radiographs?
. AP view: Salter-Harris II; Lateral view: Salter-Harris III
. AP view: Salter-Harris III; Lateral view: Salter-Harris II
. AP view: Salter-Harris IV; Lateral view: Salter-Harris II
. AP view: Salter-Harris I; Lateral view: Salter-Harris IV
. AP view: Salter-Harris III; Lateral view: Salter-Harris I

Correct Answer & Explanation

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

Explanation

A classic triplane fracture is a Salter-Harris IV equivalent but appears as a Salter-Harris III fracture on the anteroposterior (AP) radiograph and a Salter-Harris II fracture on the lateral radiograph. It typically occurs during the transitional period of physeal closure.

Question 2674

Topic: 4. Pediatrics

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip. At the 2-week follow-up, the parents report that the child has stopped extending the knee on the treated side. What is the most likely cause of this complication?

. Excessive hip abduction
. Excessive hip adduction
. Excessive hip flexion
. Inadequate hip flexion
. Avascular necrosis of the femoral head

Correct Answer & Explanation

. Excessive hip abduction

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, caused by excessive hip flexion that compresses the nerve. It presents as decreased active quadriceps function (lack of knee extension) and resolves with temporary loosening or discontinuation of the flexion straps.

Question 2675

Topic: 4. Pediatrics

A 4-year-old child presents with a congenital spinal deformity. Radiographs demonstrate a fully unsegmented unilateral bar with a contralateral hemivertebra at the same level. What is the expected natural history of this specific deformity?

. Spontaneous resolution with growth
. Slow progression manageable with a TLSO brace
. Rapid, inexorable progression requiring early surgical fusion
. Progression only during the adolescent growth spurt
. Stable deformity not requiring intervention

Correct Answer & Explanation

. Spontaneous resolution with growth

Explanation

An unsegmented bar with a contralateral hemivertebra has the highest risk of rapid and severe progression among congenital scoliosis patterns. Early surgical intervention (in situ fusion or hemivertebra excision with fusion) is essential to prevent severe deformity.

Question 2676

Topic: Pediatric Hip

A 3-year-old girl presents with a painless limp. Examination reveals a positive Trendelenburg sign on the right. Radiographs confirm an untreated, complete right-sided developmental dislocation of the hip (DDH). What is the most appropriate initial definitive management?

. Pavlik harness application
. Closed reduction and spica cast application
. Open reduction alone
. Open reduction combined with pelvic and femoral shortening osteotomies
. Observation until skeletal maturity followed by total hip arthroplasty

Correct Answer & Explanation

. Pavlik harness application

Explanation

In a child older than 2 to 3 years with an untreated complete DDH, significant acetabular dysplasia and soft tissue contractures are present. Management typically requires an open reduction, a pelvic osteotomy to correct acetabular dysplasia, and a femoral shortening osteotomy to reduce the joint without excessive pressure.

Question 2677

Topic: Pediatric Hip

A 12-year-old obese boy presents with acute, severe hip pain and inability to bear weight after a minor twisting injury. Radiographs confirm a severe, unstable slipped capital femoral epiphysis (SCFE). What is the most devastating complication directly associated with the instability of this specific fracture pattern?

. Chondrolysis
. Avascular necrosis of the femoral head
. Early onset osteoarthritis
. Femoroacetabular impingement
. Contralateral slip

Correct Answer & Explanation

. Chondrolysis

Explanation

An unstable SCFE (defined by the inability to bear weight even with crutches) has a significantly higher risk of avascular necrosis (up to 47%) compared to stable slips. The disruption of the precarious retinacular blood supply during the acute slip or forced reduction causes the AVN.

Question 2678

Topic: Pediatric Upper Extremity & Spine
A 6-year-old girl sustains an extension-type Gartland III supracondylar humerus fracture. Upon initial clinical evaluation, she is unable to flex the interphalangeal joint of her thumb and the distal interphalangeal joint of her index finger. Which nerve is most likely injured?
. Anterior interosseous nerve
. Radial nerve
. Ulnar nerve
. Posterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The anterior interosseous nerve (AIN), a branch of the median nerve, is the most commonly injured nerve in extension-type supracondylar fractures. An AIN palsy presents with the inability to form an 'OK' sign due to weakness of the flexor pollicis longus and flexor digitorum profundus to the index finger.

Question 2679

Topic: Pediatric Hip

During ultrasound screening for DDH in a 6-week-old infant, the Graf classification is utilized. What specifically does the alpha angle measure on the coronal ultrasound image?

. The degree of cartilaginous roof coverage
. The degree of bony roof coverage
. The depth of the pulvinar
. The inversion of the limbus
. The angle of the femoral neck anteversion

Correct Answer & Explanation

. The degree of cartilaginous roof coverage

Explanation

In the Graf ultrasound method, the alpha angle measures the concavity of the bony acetabular roof relative to the straight iliac bone. An alpha angle greater than 60 degrees is considered normal and indicates adequate bony coverage.

Question 2680

Topic: Pediatric Hip

A 4-month-old girl with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the infant exhibits decreased spontaneous movement of the affected side's knee and no active knee extension. What is the most likely cause of this finding?

. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Obturator nerve palsy
. Septic arthritis of the hip
. Sciatic nerve palsy

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Excessive hip flexion in a Pavlik harness can lead to femoral nerve palsy, presenting as decreased active knee extension. The harness must be adjusted or temporarily discontinued to allow neurological recovery.

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