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4. Pediatrics MCQs

Practice Set 146 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 2901

Topic: Pediatric Upper Extremity & Spine

A 12-year-old girl presents with adolescent idiopathic scoliosis. She is premenarchal and has a Risser stage of 0. Standing radiographs demonstrate a right thoracic curve of 32 degrees. What is the most appropriate management?

. Observation with repeat radiographs in 6 months
. Physical therapy and stretching exercises
. Thoracolumbosacral orthosis (TLSO) bracing
. Posterior spinal fusion
. Anterior vertebral body tethering

Correct Answer & Explanation

. Observation with repeat radiographs in 6 months

Explanation

Bracing is definitively indicated in a growing child (Risser 0-2, premenarchal) with an idiopathic curve measuring 25 to 45 degrees. Evidence shows it significantly decreases the likelihood of curve progression to the surgical threshold.

Question 2902

Topic: 4. Pediatrics

An ultrasound of the hip is performed on a 6-week-old infant suspected of having DDH. Which of the following sonographic measurements is most diagnostic of a dysplastic hip?

. Alpha angle > 60 degrees
. Beta angle < 55 degrees
. Alpha angle < 60 degrees
. Femoral head coverage > 50%
. Presence of the femoral head ossific nucleus

Correct Answer & Explanation

. Alpha angle > 60 degrees

Explanation

The alpha angle measures the osseous roof of the acetabulum on coronal ultrasound. An alpha angle of less than 60 degrees indicates inadequate osseous coverage and acetabular dysplasia.

Question 2903

Topic: Pediatric Upper Extremity & Spine

A 14-year-old girl with adolescent idiopathic scoliosis presents for follow-up. Standing full-spine radiographs show a right thoracic curve of 55 degrees. She is post-menarchal and Risser 4. What is the most appropriate treatment recommendation?

. Continuation of TLSO bracing until Risser 5
. Posterior spinal fusion
. Anterior vertebral body tethering
. Night-time only bracing
. Observation with radiographs in 1 year

Correct Answer & Explanation

. Continuation of TLSO bracing until Risser 5

Explanation

In a skeletally mature or nearly mature adolescent (Risser 4), a thoracic curve of 50 degrees or more is highly likely to continue progressing into adulthood. Surgical correction with posterior spinal fusion is the standard indication.

Question 2904

Topic: 4. Pediatrics

An infant is born with bilateral dislocated hips and severe contractures of multiple joints consistent with arthrogryposis multiplex congenita. What is the expected outcome regarding the management of these teratologic hip dislocations?

. High success rate with a Pavlik harness
. Rigid abduction bracing is the definitive treatment
. Spontaneous relocation occurs frequently during the first year of life
. High likelihood of requiring open surgical reduction
. Surgical intervention is absolutely contraindicated

Correct Answer & Explanation

. High success rate with a Pavlik harness

Explanation

Teratologic hip dislocations, such as those associated with arthrogryposis or spina bifida, are inherently rigid and typically fail conservative orthotic treatment. They almost universally require open reduction to achieve stable relocation.

Question 2905

Topic: 4. Pediatrics

A 12-year-old boy presents with an acute ankle injury. Radiographs reveal a distal tibia fracture that appears as a Salter-Harris III injury on the AP view and a Salter-Harris II injury on the lateral view. What is the most appropriate anatomical classification of this fracture?

. Tillaux fracture
. Triplane fracture
. Pilon fracture
. Cotton fracture
. Wagstaffe fracture

Correct Answer & Explanation

. Tillaux fracture

Explanation

A triplane fracture is a transitional fracture of the distal tibia occurring in three planes. It is anatomically a Salter-Harris IV equivalent but classically presents with the appearance of a Salter-Harris III on the AP radiograph and a Salter-Harris II on the lateral radiograph.

Question 2906

Topic: 4. Pediatrics

During the application of a spica cast for DDH, the hip is forcefully placed in a position of extreme abduction (the "frog-leg" position). What is the most devastating complication associated with this specific positioning?

. Femoral nerve palsy
. Acetabular retroversion
. Avascular necrosis of the femoral head
. Redislocation of the hip
. Premature physeal closure of the distal femur

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Forced abduction in a spica cast dramatically increases intracapsular pressure and mechanical compression on the extraosseous epiphyseal vessels. This "frog-leg" position is the primary risk factor for iatrogenic avascular necrosis (AVN) in DDH treatment.

Question 2907

Topic: Pediatric Hip

A 4-week-old female with a history of breech presentation is evaluated for hip instability. Ultrasound reveals an alpha angle of 45 degrees, a beta angle of 77 degrees, and 30% femoral head coverage bilaterally. What is the most appropriate initial management?

. Observation and repeat ultrasound in 4 weeks
. Application of a Pavlik harness
. Rigid abduction orthosis
. Closed reduction and spica casting
. Open reduction

Correct Answer & Explanation

. Observation and repeat ultrasound in 4 weeks

Explanation

An alpha angle < 60 degrees with subluxation or dislocation on ultrasound in a 4-week-old is diagnostic of DDH. The first-line treatment is a Pavlik harness to achieve reduction and promote acetabular development.

Question 2908

Topic: Pediatric Hip

A 6-month-old girl has been treated with a Pavlik harness for 4 weeks for a dislocated left hip. A follow-up ultrasound confirms that the hip remains dislocated within the harness. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 2 weeks
. Switch to a rigid abduction orthosis (e.g., Ilfeld brace)
. Closed reduction and spica casting
. Open reduction and spica casting
. Femoral varus derotational osteotomy

Correct Answer & Explanation

. Continue the Pavlik harness for an additional 2 weeks

Explanation

Continued use of a Pavlik harness for a dislocated hip beyond 3 to 4 weeks without achieving reduction increases the risk of posterior acetabular wear ("Pavlik harness disease"). The next appropriate step is closed reduction and spica casting under anesthesia.

Question 2909

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a widely displaced extension-type supracondylar humerus fracture. After closed reduction and percutaneous pinning, the hand is pink and warm, but the radial pulse remains nonpalpable. Capillary refill is less than 2 seconds. What is the most appropriate next step?

. Remove the pins and re-reduce the fracture
. Perform an immediate brachial artery exploration
. Perform a CT angiogram of the upper extremity
. Admit for observation and arm elevation
. Consult vascular surgery for a bypass graft

Correct Answer & Explanation

. Remove the pins and re-reduce the fracture

Explanation

A "pink, pulseless" hand after anatomic reduction and pinning of a supracondylar humerus fracture typically indicates vascular spasm. It is best managed with close observation and elevation, as collateral circulation is adequate.

Question 2910

Topic: Pediatric Upper Extremity & Spine

An 11-year-old girl presents with adolescent idiopathic scoliosis. Standing radiographs reveal a right thoracic curve measuring 35 degrees. She is premenarchal and has a Risser stage of 0. What is the most appropriate management?

. Observation with repeat radiographs in 6 months
. Physical therapy focusing on core strengthening
. Thoracolumbosacral orthosis (TLSO) bracing
. 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) who present with an idiopathic scoliotic curve between 25 and 45 degrees to prevent curve progression.

Question 2911

Topic: 4. Pediatrics

A newborn is diagnosed with congenital scoliosis. Radiographs demonstrate a fully segmented unilateral unsegmented bar on the left side with a contralateral fully formed hemivertebra on the right side at the exact same level. What is the anticipated risk of curve progression for this specific deformity pattern?

. Less than 10%
. Approximately 25%
. Approximately 50%
. Approximately 75%
. Near 100%

Correct Answer & Explanation

. Less than 10%

Explanation

A unilateral unsegmented bar with a contralateral hemivertebra at the same level represents the most severe failure of formation and segmentation. This pattern carries the highest risk of curve progression, approaching 100%, and requires early prophylactic fusion.

Question 2912

Topic: Pediatric Hip

During the treatment of developmental dysplasia of the hip (DDH) with closed reduction and spica casting, which position places the hip at the greatest risk for avascular necrosis (AVN) of the femoral head?

. Hip flexion greater than 90 degrees
. Hip extension less than 0 degrees
. Hip abduction greater than 60 degrees
. Hip adduction greater than 10 degrees
. Internal rotation greater than 20 degrees

Correct Answer & Explanation

. Hip flexion greater than 90 degrees

Explanation

Extreme hip abduction (the "frog-leg" position) forces the cartilaginous femoral head tightly against the acetabulum, compressing the extracapsular epiphyseal vessels and significantly increasing the risk of avascular necrosis.

Question 2913

Topic: Pediatric Hip

A 4-year-old girl is brought in for a painless limp. Pelvic radiographs show a unilaterally dislocated left hip with a false acetabulum and severe dysplasia of the true acetabulum. She has had no prior treatment. What is the recommended management?

. Application of a Pavlik harness
. Closed reduction and spica casting
. Open reduction alone
. Open reduction, femoral shortening osteotomy, and pelvic osteotomy
. Total hip arthroplasty

Correct Answer & Explanation

. Application of a Pavlik harness

Explanation

In a child older than 3 years presenting with untreated DDH, soft tissue contractures and severe bony dysplasia require a comprehensive approach. This includes open reduction, a femoral shortening derotational osteotomy (to reduce AVN risk), and a pelvic osteotomy to provide adequate coverage.

Question 2914

Topic: Pediatric Hip

An infant being treated in a Pavlik harness for developmental dysplasia of the hip (DDH) is noted by the parents to have stopped kicking the knee on the treated side. Physical examination confirms decreased active extension of the knee, though the foot and ankle move symmetrically. What is the most appropriate next step in management?

. Continue the harness and observe for 48 hours
. Discontinue the harness for 1 to 2 weeks
. Switch immediately to a rigid hip spica cast
. Perform immediate closed reduction under anesthesia
. Adjust the anterior straps to increase hip flexion

Correct Answer & Explanation

. Continue the harness and observe for 48 hours

Explanation

Femoral nerve palsy is a known complication of hyperflexion in a Pavlik harness. The harness should be discontinued until quadriceps function returns, which usually occurs within 1 to 2 weeks.

Question 2915

Topic: 4. Pediatrics

During attempted closed reduction of a dislocated hip in a 12-month-old child with DDH, concentric reduction cannot be achieved. Which of the following anatomic structures is NOT a typical obstacle to closed reduction?

. Inverted limbus
. Hypertrophied ligamentum teres
. Hypertrophied pulvinar
. Pectineus muscle
. Transverse acetabular ligament

Correct Answer & Explanation

. Inverted limbus

Explanation

Common blocks to closed reduction in DDH include an inverted limbus, pulvinar, elongated ligamentum teres, contracted iliopsoas, and tight transverse acetabular ligament. The pectineus muscle does not typically impede reduction.

Question 2916

Topic: 4. Pediatrics

A 14-year-old boy sustains a twisting ankle injury. Radiographs reveal a Salter-Harris III avulsion fracture of the anterolateral aspect of the distal tibial epiphysis (Tillaux fracture). Which ligament is responsible for avulsing this fragment?

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

Correct Answer & Explanation

. Anterior talofibular ligament

Explanation

A Tillaux fracture is caused by an external rotation force that creates tension on the anterior inferior tibiofibular ligament (AITFL). This tension avulses the anterolateral distal tibial epiphysis because the medial physis has already fused.

Question 2917

Topic: 4. Pediatrics

A classic triplane fracture of the distal tibia in an adolescent traverses the metaphysis, physis, and epiphysis. Based on the Salter-Harris classification system, what type of physeal injury does this represent?

. Salter-Harris I
. Salter-Harris II
. Salter-Harris III
. Salter-Harris IV
. Salter-Harris V

Correct Answer & Explanation

. Salter-Harris I

Explanation

A triplane fracture has a coronal fracture in the metaphysis, an axial fracture through the physis, and a sagittal fracture in the epiphysis. Because the fracture crosses all layers from the metaphysis to the joint surface, it is a Salter-Harris IV equivalent.

Question 2918

Topic: 4. Pediatrics

A 6-week-old female infant born in the breech position presents for a routine evaluation. Her physical examination reveals equal leg lengths and negative Ortolani and Barlow maneuvers. What is the most appropriate imaging modality to evaluate for DDH at this age?

. Anteroposterior pelvis radiograph
. Frog-leg lateral radiograph
. MRI of the pelvis
. Ultrasound of the hips
. CT scan of the hips

Correct Answer & Explanation

. Anteroposterior pelvis radiograph

Explanation

For an infant younger than 4 to 6 months with risk factors for DDH, dynamic ultrasound is the screening modality of choice. The femoral head and acetabulum are largely cartilaginous and not well visualized on plain radiographs at this age.

Question 2919

Topic: Pediatric Upper Extremity & Spine

Brace treatment for adolescent idiopathic scoliosis is generally most effective and indicated for which of the following patient profiles?

. A Risser 4 patient with a 30-degree curve
. A Risser 0 patient with a 35-degree curve
. A Risser 1 patient with a 55-degree curve
. A Risser 5 patient with a 20-degree curve
. A Risser 0 patient with an 15-degree curve

Correct Answer & Explanation

. A Risser 4 patient with a 30-degree curve

Explanation

Bracing in adolescent idiopathic scoliosis is indicated for skeletally immature patients (Risser 0-2) with progressive curves between 25 and 45 degrees. Curves over 45 degrees usually require surgery, while non-progressive curves under 25 degrees are observed.

Question 2920

Topic: Pediatric Hip

A 2-year-old girl recently immigrated to the United States and is noted to have a painless limp. Examination reveals a positive Galeazzi sign and severely limited hip abduction. Radiographs show a dislocated left hip with a dysplastic acetabulum. What is the most appropriate treatment?

. Pavlik harness trial for 6 weeks
. Closed reduction and spica casting
. Open reduction, femoral shortening, and pelvic osteotomy
. Proximal femoral epiphysiodesis
. In situ shelf arthroplasty

Correct Answer & Explanation

. Pavlik harness trial for 6 weeks

Explanation

In a child older than 18-24 months presenting with untreated DDH, closed reduction carries a very high risk of AVN and is rarely successful. Treatment requires open reduction, often combined with femoral shortening to reduce joint tension and a pelvic osteotomy for acetabular coverage.

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