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4. Pediatrics MCQs

Practice Set 148 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 2941

Topic: Pediatric Hip

A 4-year-old girl presents with an untreated, completely dislocated left hip. Radiographs confirm developmental dysplasia of the hip (DDH) with a false acetabulum and significant superior migration of the femoral head. What is the most appropriate surgical management?

. Closed reduction and spica cast application
. Open reduction alone
. Open reduction with femoral shortening osteotomy and pelvic osteotomy
. Innominate osteotomy alone
. Varus derotational femoral osteotomy alone

Correct Answer & Explanation

. Closed reduction and spica cast application

Explanation

In a 4-year-old with an untreated dislocated hip, open reduction is required. Femoral shortening is necessary to reduce joint reaction forces and minimize the risk of osteonecrosis, while a pelvic osteotomy addresses the secondary acetabular dysplasia.

Question 2942

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy falls from monkey bars and sustains a widely displaced extension-type supracondylar humerus fracture. Examination reveals an absent radial pulse but a warm, pink hand. After closed reduction and percutaneous pinning, the hand remains warm and pink, but the pulse remains absent. What is the next best step in management?

. Immediate exploration of the brachial artery
. Arteriography
. Observation and admission for neurovascular checks
. Removal of pins and open reduction
. Prophylactic forearm fasciotomy

Correct Answer & Explanation

. Immediate exploration of the brachial artery

Explanation

A "pink, pulseless" hand after anatomical reduction and pinning of a supracondylar humerus fracture typically indicates adequate collateral circulation. Observation is indicated as the pulse often returns within a few days; vascular exploration is reserved for a pale, pulseless hand.

Question 2943

Topic: 4. Pediatrics

A 3-month-old infant is being treated with a Pavlik harness for a reducible, dislocated right hip. During the follow-up visit, you notice the infant lacks active knee extension on the right side. What complication is most likely occurring?

. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Sciatic nerve palsy
. Obturator nerve palsy
. Inferior dislocation of the hip

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Femoral nerve palsy in a Pavlik harness is typically caused by excessive hip flexion. The harness must be adjusted to reduce flexion or temporarily removed to allow nerve recovery, as persistent hyperflexion can lead to permanent palsy or inferior hip dislocation.

Question 2944

Topic: 4. Pediatrics

A 13-year-old boy presents with a painful, swollen ankle after a skateboarding injury. Radiographs show a Salter-Harris III fracture of the anterolateral distal tibia. What is the primary pathomechanical force and structure responsible for this specific fracture pattern?

. Avulsion by the anterior inferior tibiofibular ligament (AITFL) due to external rotation
. Avulsion by the posterior inferior tibiofibular ligament (PITFL) due to internal rotation
. Direct axial load on a plantarflexed foot causing talar impaction
. Avulsion by the deltoid ligament due to an eversion force
. Shear force from the fibula during forced dorsiflexion

Correct Answer & Explanation

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

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia epiphysis. It occurs secondary to an external rotation force where the AITFL avulses the anterolateral fragment due to the asymmetric closure pattern of the distal tibial physis.

Question 2945

Topic: Pediatric Upper Extremity & Spine

A 14-year-old girl with adolescent idiopathic scoliosis (AIS) has a right thoracic curve of 55 degrees and a left lumbar curve of 30 degrees. On side-bending radiographs, the lumbar curve reduces to 10 degrees. According to the Lenke classification, what type of curve pattern is this, and what is the recommended surgical approach?

. Lenke 1: Selective thoracic fusion
. Lenke 2: Double thoracic fusion
. Lenke 3: Thoracic and lumbar fusion
. Lenke 5: Selective lumbar fusion
. Lenke 6: Thoracolumbar/lumbar fusion

Correct Answer & Explanation

. Lenke 1: Selective thoracic fusion

Explanation

This is a Lenke 1 (main thoracic) curve pattern, because the lumbar curve is nonstructural (bends out to less than 25 degrees). The standard surgical management is a selective thoracic fusion, which spares the lumbar spine to preserve spinal mobility.

Question 2946

Topic: 4. Pediatrics

A 6-week-old female infant, born breech at 39 weeks gestation, presents for a routine check-up. Clinical examination of the hips reveals symmetric thigh folds and negative Barlow and Ortolani maneuvers bilaterally. What is the most appropriate next step in hip screening for this patient?

. No further imaging is required due to normal clinical exam
. AP radiograph of the pelvis today
. Ultrasound of the hips today
. Re-examine the hips at 4 months of age and obtain a radiograph if abnormal
. Immediate application of a Pavlik harness prophylactically

Correct Answer & Explanation

. No further imaging is required due to normal clinical exam

Explanation

Breech presentation and female sex are major risk factors for DDH. Current clinical practice guidelines strongly recommend screening ultrasound at 4 to 6 weeks of age for infants with these risk factors, regardless of a normal clinical examination.

Question 2947

Topic: Pediatric Hip

A 3-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the mother notes the child is no longer kicking her left leg. Examination reveals absent active knee extension on the left. What is the most appropriate next step in management?

. Increase the tension on the anterior straps
. Increase the tension on the posterior straps
. Discontinue the Pavlik harness
. Perform an emergent closed reduction
. Switch to a rigid hip abduction orthosis

Correct Answer & Explanation

. Increase the tension on the anterior straps

Explanation

The patient has developed a femoral nerve palsy, a known complication of Pavlik harness treatment caused by excessive hip flexion. The appropriate management is immediate discontinuation of the harness to allow for nerve recovery. Once neurologic function returns, alternative treatments such as rigid bracing or closed reduction should be considered.

Question 2948

Topic: 4. Pediatrics

A 6-week-old female infant undergoes a screening hip ultrasound. The alpha angle is 45 degrees and the beta angle is 80 degrees, indicating a laterally displaced cartilage roof. What is the most appropriate next step in management?

. Observation with repeat ultrasound in 4 weeks
. Application of a Pavlik harness
. Closed reduction and spica casting
. Open reduction
. Reassurance as this is a physiologically immature hip

Correct Answer & Explanation

. Observation with repeat ultrasound in 4 weeks

Explanation

An alpha angle of less than 50 degrees with a laterally displaced cartilage roof indicates a Graf Type III dysplastic hip. This requires immediate treatment with a Pavlik harness to achieve and maintain concentric reduction. Observation is only appropriate for physiologically immature hips (Graf IIa) with an alpha angle of 50-59 degrees in infants under 3 months of age.

Question 2949

Topic: 4. Pediatrics

A 13-year-old boy sustains an ankle injury resulting in a juvenile Tillaux fracture. Which of the following describes the normal sequence of closure of the distal tibial physis, predisposing the patient to this specific fracture pattern?

. Central, then anteromedial, then posteromedial, then lateral
. Lateral, then central, then medial
. Medial, then central, then lateral
. Posteromedial, then anteromedial, then lateral
. Central, then medial, then lateral

Correct Answer & Explanation

. Central, then anteromedial, then posteromedial, then lateral

Explanation

The distal tibial physis closes in a predictable sequence: central, then medial, and finally lateral. The anterolateral portion is the last to close, leaving it vulnerable to avulsion by the anterior inferior tibiofibular ligament during external rotation injuries (juvenile Tillaux fracture).

Question 2950

Topic: Pediatric Hip

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip. At the 2-week follow-up, the mother notes the child is no longer kicking her leg on the affected side. On examination, there is decreased active knee extension. What is the most appropriate next step in management?

. Continue the harness and reassure the mother
. Adjust the anterior straps to decrease hip flexion
. Adjust the posterior straps to increase hip abduction
. Remove the harness and switch to a rigid abduction orthosis
. Obtain an urgent MRI of the lumbar spine

Correct Answer & Explanation

. Continue the harness and reassure the mother

Explanation

The scenario describes a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The appropriate management is to adjust the anterior straps to decrease hip flexion or temporarily remove the harness until nerve function recovers.

Question 2951

Topic: 4. Pediatrics

Which of the following ultrasound findings is most consistent with a normal infant hip at 6 weeks of age?

. Alpha angle > 60 degrees and beta angle < 55 degrees
. Alpha angle < 50 degrees and beta angle > 77 degrees
. Alpha angle > 60 degrees and femoral head coverage < 30%
. Alpha angle < 60 degrees and beta angle < 55 degrees
. Alpha angle < 43 degrees and beta angle > 77 degrees

Correct Answer & Explanation

. Alpha angle > 60 degrees and beta angle < 55 degrees

Explanation

According to the Graf classification for developmental dysplasia of the hip, a normal infant hip (Type I) is characterized by an alpha angle greater than 60 degrees and a beta angle less than 55 degrees, with femoral head coverage greater than 50%.

Question 2952

Topic: Pediatric Upper Extremity & Spine

A 13-year-old girl with adolescent idiopathic scoliosis presents for evaluation. Radiographs reveal a right thoracic curve of 35 degrees. Her Risser sign is 1, and she is premenarcheal. What is the most appropriate management?

. Observation with serial radiographs every 6 months
. Part-time nighttime bracing
. Full-time TLSO bracing
. Posterior spinal fusion
. Anterior tethering procedure

Correct Answer & Explanation

. Observation with serial radiographs every 6 months

Explanation

Full-time bracing (TLSO) is indicated for immature patients (Risser 0-2, premenarcheal) with idiopathic curves between 25 and 45 degrees. It has been shown to significantly decrease the risk of curve progression to the surgical threshold.

Question 2953

Topic: 4. Pediatrics

A 14-year-old boy sustains a Salter-Harris type III fracture of the medial malleolus. The horizontal component of the fracture typically propagates through which of the following anatomic zones of the physis?

. 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 structurally weak zone of hypertrophy of the physis. A type III fracture then exits vertically through the epiphysis, involving the joint space.

Question 2954

Topic: Pediatric Hip

An 18-month-old child presents with untreated developmental dysplasia of the right hip. Closed reduction is attempted but is unsuccessful due to soft tissue interposition. Which of the following structures is most commonly a block to closed reduction in this setting?

. Ligamentum teres
. Gluteus medius muscle
. Ischiofemoral ligament
. Pectineus muscle
. Iliotibial band

Correct Answer & Explanation

. Ligamentum teres

Explanation

Common blocks to closed reduction in DDH include an inverted limbus, hypertrophied ligamentum teres, contracted transverse acetabular ligament, and a constricted iliopsoas tendon.

Question 2955

Topic: 4. Pediatrics

A 14-year-old girl presents with an acute distal tibial fracture. Radiographs show a Salter-Harris type III fracture of the anterolateral distal tibial epiphysis. What is the mechanism of injury and the deforming force?

. Supination-inversion; anterior talofibular ligament avulsion
. External rotation; anterior inferior tibiofibular ligament avulsion
. Pronation-abduction; deltoid ligament pull
. Plantarflexion; Achilles tendon avulsion
. Axial load; calcaneofibular ligament tear

Correct Answer & Explanation

. Supination-inversion; anterior talofibular ligament avulsion

Explanation

This describes a juvenile Tillaux fracture, caused by an external rotation force. The anterior inferior tibiofibular ligament (AITFL) avulses the anterolateral distal tibial epiphysis, which is the last portion of the physis to close.

Question 2956

Topic: 4. Pediatrics

A 9-year-old boy is found to have a physeal bar across the central 30% of his distal femoral physis following a previous Salter-Harris type II fracture. He has a 2 cm leg length discrepancy and 4 years of remaining growth. What is the most appropriate surgical management?

. Contralateral distal femoral epiphysiodesis
. Ipsilateral distal femoral completion epiphysiodesis
. Physeal bar resection and interposition of fat or cranioplast
. Femoral lengthening via an intramedullary device
. Observation until skeletal maturity

Correct Answer & Explanation

. Contralateral distal femoral epiphysiodesis

Explanation

Physeal bar resection is indicated when the bar occupies less than 50% of the cross-sectional area of the physis and the child has at least 2 years of remaining growth. Interposition material is used to prevent reformation.

Question 2957

Topic: Pediatric Hip

The "safe zone" of Ramsey in the treatment of DDH with a spica cast is defined as the position between:

. Maximum internal rotation and maximum external rotation
. Maximum hip flexion and minimum hip extension
. The angle of maximal abduction and the angle of redislocation
. Maximum adduction and minimum abduction
. The angle of functional coverage and the angle of subluxation

Correct Answer & Explanation

. Maximum internal rotation and maximum external rotation

Explanation

Ramsey's safe zone for DDH reduction is the arc of abduction between the angle of redislocation (when the hip adducts) and the angle of maximal abduction. Immobilization within this zone minimizes the risk of both redislocation and avascular necrosis.

Question 2958

Topic: 4. Pediatrics

A 6-week-old female infant, born in breech presentation, undergoes a screening hip ultrasound. The alpha angle is measured at 45 degrees, and the beta angle is 80 degrees. What is the most appropriate next step in management?

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

Correct Answer & Explanation

. Observation with repeat ultrasound in 4 weeks

Explanation

Graf type IIc or III indicates dysplasia or subluxation based on an alpha angle < 60 degrees and beta angle > 77 degrees. Treatment with a Pavlik harness is indicated to promote acetabular remodeling.

Question 2959

Topic: 4. Pediatrics

A 3-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip. The parents report that the child has stopped kicking the affected leg. On examination, there is decreased active knee extension. Which of the following harness adjustments is required?

. Decrease flexion of the anterior strap
. Increase flexion of the anterior strap
. Decrease abduction of the posterior strap
. Increase abduction of the posterior strap
. Discontinue the harness entirely

Correct Answer & Explanation

. Decrease flexion of the anterior strap

Explanation

Hyperflexion of the hips in a Pavlik harness can cause femoral nerve palsy due to compression against the rim of the pelvis. Decreasing the flexion of the anterior strap relieves this compression.

Question 2960

Topic: Pediatric Hip

An 18-month-old girl presents with a painless limp and a positive Trendelenburg sign on the right. Radiographs reveal a dislocated right hip with a false acetabulum and breaking of Shenton's line.

What is the most appropriate definitive management?

. Pavlik harness
. Closed reduction and spica casting
. Open reduction with possible pelvic/femoral osteotomy
. Observation until age 3
. Hip arthroscopy

Correct Answer & Explanation

. Pavlik harness

Explanation

Children over 18 months of age with a dislocated hip typically have significant soft tissue contractures and acetabular dysplasia. Open reduction, often combined with pelvic or femoral osteotomies, is required to achieve and maintain concentric reduction.

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