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4. Pediatrics MCQs

Practice Set 128 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 2541

Topic: Pediatric Hip

A 14-year-old boy undergoes in situ percutaneous pinning for a stable slipped capital femoral epiphysis (SCFE). Which of the following screw configurations provides the optimal balance of biomechanical stability and minimized complication risk?

. Two parallel screws placed in the center of the epiphysis
. One single screw placed in the center-center position
. Three divergent screws spanning the physis
. One single screw placed in the anterosuperior quadrant
. Two crossed screws engaging the posterior cortex

Correct Answer & Explanation

. One single screw placed in the center-center position

Explanation

A single screw placed in the center-center of the epiphysis provides sufficient biomechanical stability for a stable SCFE. Adding a second screw does not clinically improve stability but significantly increases the risk of articular penetration and chondrolysis.

Question 2542

Topic: Pediatric Hip

Following pinning of a SCFE, a 13-year-old patient develops a stiff, painful hip with a 15-degree flexion contracture. Radiographs reveal global narrowing of the joint space to less than 3 mm. What is the most likely diagnosis?

. Osteonecrosis of the femoral head
. Septic arthritis
. Chondrolysis
. Hardware failure
. Heterotopic ossification

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis involves the acute dissolution of articular cartilage, presenting with marked stiffness, pain, and global joint space narrowing on radiographs. It is a severe complication of SCFE, highly associated with unrecognized intra-articular hardware penetration.

Question 2543

Topic: 4. Pediatrics

A 2.5-year-old child presents with an untreated, completely dislocated left hip (DDH) and is scheduled for an open reduction. To minimize the risk of osteonecrosis during the reduction in a child of this age, which adjunctive procedure is most commonly required?

. Adductor tenotomy alone
. Iliopsoas transfer
. Femoral shortening osteotomy
. Chiari osteotomy
. Greater trochanteric epiphysiodesis

Correct Answer & Explanation

. Femoral shortening osteotomy

Explanation

In children older than 2 to 3 years, chronically contracted soft tissues severely increase the joint reactive forces upon reduction. A femoral shortening osteotomy decompresses the joint, significantly reducing the risk of avascular necrosis during open reduction.

Question 2544

Topic: Pediatric Hip

When evaluating an AP pelvis radiograph for a suspected slipped capital femoral epiphysis (SCFE), what defines an abnormal Klein's line?

. The line drawn along the superior femoral neck intersects more of the epiphysis than the contralateral side
. The line drawn along the superior femoral neck intersects less or none of the lateral epiphysis compared to the contralateral side
. The line drawn along the inferior femoral neck fails to intersect the lesser trochanter
. The line drawn along the physeal plate intersects the fovea capitis
. The line drawn along the central neck axis passes superior to the fovea

Correct Answer & Explanation

. The line drawn along the superior femoral neck intersects less or none of the lateral epiphysis compared to the contralateral side

Explanation

Klein's line is drawn along the superior border of the femoral neck on an AP radiograph. In SCFE, the epiphysis is displaced posteriorly and inferiorly, causing Klein's line to intersect less of the lateral epiphysis (or miss it entirely) compared to the normal contralateral hip.

Question 2545

Topic: 4. Pediatrics

An infant is diagnosed with a teratologic hip dislocation associated with arthrogryposis multiplex congenita. What is the most appropriate initial management strategy for the hip?

. Immediate application of a Pavlik harness
. Immediate application of a hip spica cast without reduction
. Observation only until skeletal maturity
. Early open reduction, often with femoral shortening
. Serial steroid injections into the hip joint capsule

Correct Answer & Explanation

. Early open reduction, often with femoral shortening

Explanation

Teratologic dislocations involve severe, rigid soft-tissue contractures and typically do not respond to a Pavlik harness or closed reduction methods. Early open reduction, frequently combined with capsulorrhaphy and a femoral shortening osteotomy, is the standard of care to achieve a concentric reduction.

Question 2546

Topic: 4. Pediatrics

A 6-year-old boy falls from monkey bars and sustains a displaced 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 warm and pink, and capillary refill is less than 2 seconds, but the pulse is still absent on Doppler. What is the most appropriate next step in management?

. Immediate exploration of the brachial artery
. Observation and admission for close neurovascular monitoring
. Perform a CT angiogram of the upper extremity
. Remove the pins and attempt open reduction
. Administer intra-arterial vasodilators

Correct Answer & Explanation

. Observation and admission for close neurovascular monitoring

Explanation

In a pediatric supracondylar fracture with a "pulseless, pink" hand post-reduction, the extremity is well-perfused via collateral circulation. The standard of care is close clinical observation rather than immediate surgical exploration or angiography.

Question 2547

Topic: Pediatric Hip

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During the follow-up visit, the parents report the infant is no longer actively extending the knee on the treated side. What is the most appropriate management?

. Continue the harness and add physical therapy
. Tighten the anterior straps to increase flexion
. Remove the harness and transition to a spica cast
. Loosen the anterior straps or temporarily discontinue the harness
. Perform an immediate ultrasound to rule out hip dislocation

Correct Answer & Explanation

. Loosen the anterior straps or temporarily discontinue the harness

Explanation

Decreased active knee extension indicates a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. Management consists of loosening the anterior straps or temporarily discontinuing the harness until nerve function returns.

Question 2548

Topic: 4. Pediatrics

When correcting a classic congenital idiopathic clubfoot using the Ponseti method, what is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Varus, Equinus, Adductus

Explanation

The Ponseti method corrects deformities in a specific sequence remembered by the acronym CAVE: Cavus (elevating the first ray), Adductus, Varus, and finally Equinus (usually requiring a percutaneous Achilles tenotomy).

Question 2549

Topic: 4. Pediatrics
A 13-year-old girl sustains an ankle injury while skateboarding. Radiographs show a Salter-Harris III fracture of the anterolateral distal tibia. Which of the following ligaments imparts the avulsion force responsible for this specific fracture pattern?
. Anterior talofibular ligament
. Calcaneofibular ligament
. Anterior inferior tibiofibular ligament
. Posterior inferior tibiofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. It is caused by an avulsion force from the anterior inferior tibiofibular ligament (AITFL) during an external rotation injury.

Question 2550

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 32 presents with a left-sided stable slipped capital femoral epiphysis (SCFE). Which of the following is considered an absolute indication for prophylactic in situ pinning of the asymptomatic contralateral right hip?

. Age greater than 14 years
. Presence of endocrinopathy (e.g., hypothyroidism)
. Male sex
. Slit-like physis on radiograph
. Bilateral knee pain

Correct Answer & Explanation

. Presence of endocrinopathy (e.g., hypothyroidism)

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended in patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) or prior radiation therapy due to the high risk of bilateral involvement.

Question 2551

Topic: 4. Pediatrics

A 14-year-old boy sustains an ankle fracture. CT imaging confirms a classic triplane fracture. This injury consists of which of the following fracture patterns?

. Sagittal through the epiphysis, axial through the physis, and coronal through the metaphysis
. Coronal through the epiphysis, sagittal through the physis, and axial through the metaphysis
. Axial through the epiphysis, coronal through the physis, and sagittal through the metaphysis
. Sagittal through the epiphysis, coronal through the physis, and axial through the metaphysis
. Coronal through the epiphysis, axial through the physis, and sagittal through the metaphysis

Correct Answer & Explanation

. Sagittal through the epiphysis, coronal through the physis, and axial through the metaphysis

Explanation

A classic triplane ankle fracture features a sagittal fracture line through the epiphysis, an axial fracture through the physis, and a coronal fracture line extending through the posterior metaphysis.

Question 2552

Topic: 4. Pediatrics

A 9-month-old infant is brought to the emergency department with a swollen right thigh. Radiographs demonstrate a spiral fracture of the midshaft femur. The parents report the child tripped and fell while pulling to stand. Which of the following is the most appropriate next step in management?

. Immediate application of a spica cast and discharge home
. Open reduction and internal fixation with flexible nails
. Admit the patient, consult child protective services, and obtain a skeletal survey
. Perform a DEXA scan to rule out osteogenesis imperfecta
. Apply a Pavlik harness for stabilization

Correct Answer & Explanation

. Admit the patient, consult child protective services, and obtain a skeletal survey

Explanation

Femur fractures in non-ambulatory infants (under 1 year of age) are highly suspicious for non-accidental trauma. Admission, consultation with child protective services, and a full skeletal survey are mandatory.

Question 2553

Topic: Pediatric Hip
In a 7-year-old child diagnosed with Legg-Calvรฉ-Perthes disease, which of the following radiographic classifications is most prognostic for long-term hip joint congruency and outcome?
. Catterall classification
. Salter-Thompson classification
. Herring Lateral Pillar classification
. Stulberg classification
. Tonnis classification

Correct Answer & Explanation

. Herring Lateral Pillar classification

Explanation

The Herring Lateral Pillar classification, assessed during the fragmentation phase, is the most accurate prognostic indicator for long-term outcomes in Legg-Calvรฉ-Perthes disease based on the height of the lateral pillar of the femoral head.

Question 2554

Topic: Pediatric Upper Extremity & Spine

A 12-year-old girl presents with adolescent idiopathic scoliosis (AIS). She has a right thoracic curve of 35 degrees. Her Risser stage is 0, and she is pre-menarchal. What is her approximate risk of curve progression to greater than 50 degrees?

. Less than 10%
. 20-30%
. 40-50%
. 60-70%
. Greater than 90%

Correct Answer & Explanation

. Greater than 90%

Explanation

Patients with large curves (greater than 30-35 degrees) before skeletal maturity (Risser 0, pre-menarchal) have a very high risk of progression, often cited as approaching or exceeding 90%. Bracing or surgery is indicated depending on exact curve magnitude and progression.

Question 2555

Topic: Pediatric Hip

A 13-year-old boy is brought to the ED after sudden onset of severe groin pain following a minor slip. He is unable to bear weight on the affected limb. Radiographs confirm a severe slipped capital femoral epiphysis. What is the most significant complication associated with this specific injury pattern?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Coxa magna
. Femoroacetabular impingement (FAI)
. Premature physeal closure

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The inability to bear weight defines an "unstable" SCFE. Unstable SCFE has a significantly higher rate of avascular necrosis (AVN) of the femoral head (up to 47%) compared to stable SCFE.

Question 2556

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from monkey bars and presents with a Gartland type III extension-type supracondylar humerus fracture. Examination reveals an inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. Which nerve is most likely injured?
. Radial nerve
. Ulnar nerve
. Anterior interosseous 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. It is assessed by asking the patient to make an "OK" sign, which requires FPL and FDP function.

Question 2557

Topic: Pediatric Hip

Prophylactic pinning of the contralateral, asymptomatic hip is most strongly indicated in which of the following patients presenting with a unilateral slipped capital femoral epiphysis (SCFE)?

. A 12-year-old boy with idiopathic SCFE
. A 13-year-old girl with trauma-induced SCFE
. A 10-year-old girl with renal osteodystrophy
. A 14-year-old obese boy
. A 15-year-old boy with acetabular retroversion

Correct Answer & Explanation

. A 10-year-old girl with renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip is indicated in patients with metabolic or endocrine disorders (e.g., renal osteodystrophy, hypothyroidism) due to an extremely high incidence of bilateral involvement.

Question 2558

Topic: 4. Pediatrics

Which of the following pediatric physeal fractures carries the highest risk of premature physeal closure and subsequent growth arrest?

. Distal radius
. Proximal humerus
. Proximal tibia
. Distal femur
. Distal fibula

Correct Answer & Explanation

. Distal femur

Explanation

Distal femur physeal fractures carry the highest risk of premature physeal closure and growth arrest, approaching 50% in some series, largely due to the undulating topography of the physis.

Question 2559

Topic: Pediatric Lower Extremity

When utilizing the Ponseti method for the treatment of idiopathic clubfoot, what is the correct sequential order of deformity correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method corrects deformities sequentially using the CAVE acronym: Cavus (by elevating the first ray), Adductus, Varus, and finally Equinus (which often requires a percutaneous Achilles tenotomy).

Question 2560

Topic: Pediatric Hip

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During follow-up, the anterior straps are found to be adjusted such that the hips are held in 130 degrees of flexion. The infant is noted to have decreased active knee extension. What is the most likely complication?

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

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion of the hip in a Pavlik harness (>120 degrees) can compress the femoral nerve against the inguinal ligament, causing a femoral nerve palsy characterized by decreased active knee extension.

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