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4. Pediatrics MCQs

Practice Set 133 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 2641

Topic: Pediatric Hip

A 7-year-old boy presents with a painless limp of 2 months duration. Radiographs reveal fragmentation and increased density of the right capital femoral epiphysis consistent with Legg-Calve-Perthes disease. Which of the following is the most significant prognostic factor for the final outcome of his hip?

. Gender
. Weight at onset
. Age at clinical presentation
. Duration of symptoms prior to diagnosis
. Presence of a limp

Correct Answer & Explanation

. Gender

Explanation

Age at clinical presentation is the most critical prognostic factor in Legg-Calve-Perthes disease. Children who present at an older age (typically >8 years) have a higher risk of a poor radiographic and clinical outcome compared to younger children.

Question 2642

Topic: Pediatric Hip

A 2-month-old girl is being treated with a Pavlik harness for developmental dysplasia of the hip. At her 2-week follow-up, the mother reports that the infant has stopped kicking her left leg. On examination, the left knee does not actively extend, but passive range of motion is normal. Which of the following is the most appropriate management?

. Adjust the posterior strap to increase abduction
. Adjust the anterior strap to increase flexion
. Remove the harness and place in a spica cast
. Discontinue the harness temporarily
. Order an urgent MRI of the lumbar spine

Correct Answer & Explanation

. Adjust the posterior strap to increase abduction

Explanation

Transient femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion. The appropriate management is to temporarily discontinue or loosen the harness until active quadriceps function returns.

Question 2643

Topic: 4. Pediatrics
A 13-year-old boy sustains an ankle injury. Radiographs and CT scan demonstrate a fracture of the distal tibia with a sagittal fracture through the epiphysis, an axial fracture through the physis, and a coronal fracture through the posterior metaphysis. This injury is best classified as an equivalent to which Salter-Harris pattern?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type IV

Explanation

A triplane fracture involves the epiphysis, physis, and metaphysis of the distal tibia. Because the fracture line traverses all three zones, it acts biomechanically and anatomically as a Salter-Harris Type IV equivalent.

Question 2644

Topic: 4. Pediatrics
A 14-year-old girl sustains a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. What is the primary mechanism of injury for this specific fracture pattern?
. Axial loading
. Plantar flexion and inversion
. External rotation of the foot
. Direct anterior trauma
. Hyperdorsiflexion

Correct Answer & Explanation

. External rotation of the foot

Explanation

A juvenile fracture of Tillaux is an avulsion of the anterolateral distal tibial epiphysis caused by tension from the anterior inferior tibiofibular ligament (AITFL). This typically occurs due to external rotation of the foot within the mortise as the physis begins its asymmetric medial-to-lateral closure.

Question 2645

Topic: Pediatric Hip

A 14-year-old girl underwent uncomplicated in situ pinning for a stable SCFE 6 months ago. She now presents with a worsening limp and a stiff hip. Examination reveals a painful, global restriction of hip motion. Radiographs show concentric narrowing of the hip joint space. What is the most likely diagnosis?

. Avascular necrosis
. Chondrolysis
. Implant failure
. Septic arthritis
. Femoroacetabular impingement

Correct Answer & Explanation

. Avascular necrosis

Explanation

Chondrolysis is a recognized complication of SCFE characterized by acute cartilage necrosis, presenting with severe stiffness, global loss of motion, and concentric joint space narrowing on radiographs. It can occur spontaneously or secondary to hardware penetration.

Question 2646

Topic: 4. Pediatrics

A 4-week-old infant is referred for congenital muscular torticollis. The head is tilted to the right and rotated to the left. A firm mass is palpable in the right sternocleidomastoid muscle. In addition to physical therapy for the neck, what additional screening is most strongly indicated?

. Cervical spine MRI
. Ophthalmologic examination
. Ultrasound of the hips
. Renal ultrasound
. Hearing screening

Correct Answer & Explanation

. Cervical spine MRI

Explanation

Congenital muscular torticollis has a known association with developmental dysplasia of the hip (DDH), occurring in up to 10-20% of cases. Screening with a hip ultrasound is strongly recommended for these infants.

Question 2647

Topic: 4. Pediatrics

A 10-year-old boy is evaluated for a leg length discrepancy 2 years after sustaining a distal femoral physeal fracture. Radiographs show a central 30% bony bar across the distal femoral physis with 2 years of growth remaining. What is the most appropriate management?

. Physeal bar resection with fat interposition
. Complete epiphysiodesis of the distal femur
. Distal femoral osteotomy
. Ilizarov lengthening
. Observation until skeletal maturity

Correct Answer & Explanation

. Physeal bar resection with fat interposition

Explanation

For a physeal bar occupying less than 50% of the physis in a child with at least 2 years of remaining growth, resection of the bar with interposition of fat or Cranioplast is the recommended treatment to restore longitudinal growth.

Question 2648

Topic: 4. Pediatrics

A 7-year-old girl with spastic quadriplegic cerebral palsy presents for routine evaluation. Pelvic radiographs demonstrate a Reimers migration percentage of 55% in the right hip. There is no evidence of joint space narrowing or femoral head deformity. What is the most appropriate surgical management?

. Adductor tenotomy alone
. Varus derotational osteotomy (VDRO) and pelvic osteotomy
. Proximal femoral resection (Girdlestone)
. Total hip arthroplasty
. Observation with serial radiographs

Correct Answer & Explanation

. Adductor tenotomy alone

Explanation

In a child with spastic cerebral palsy and hip subluxation with a migration percentage >50%, soft tissue release alone is insufficient. Bony reconstruction with a varus derotational osteotomy (VDRO) and a concurrent pelvic osteotomy is required to provide stable, long-term coverage.

Question 2649

Topic: Pediatric Hip

A 12-year-old obese boy presents with acute-on-chronic left hip pain and inability to bear weight. Radiographs confirm an unstable slipped capital femoral epiphysis (SCFE). Which of the following is the most appropriate initial management to minimize the risk of avascular necrosis?

. Urgent open reduction and internal fixation
. Closed reduction and spica casting
. In situ pinning with a single cannulated screw
. Urgent capsulotomy and in situ pinning
. Prophylactic pinning of the contralateral hip

Correct Answer & Explanation

. Urgent open reduction and internal fixation

Explanation

Unstable SCFE is associated with a high rate of avascular necrosis. Urgent capsulotomy and in situ pinning or gentle reduction are recommended to decompress the joint and stabilize the epiphysis.

Question 2650

Topic: Pediatric Hip

A 3-month-old girl is being treated for developmental dysplasia of the hip with a Pavlik harness. During a follow-up visit, the mother notes that the child is no longer kicking her left leg. Examination reveals absent active knee extension on the left. The most appropriate next step is to:

. Adjust the anterior straps to increase flexion
. Adjust the posterior straps to decrease abduction
. Discontinue the harness immediately
. Schedule an urgent MRI of the lumbar spine
. Transition to a rigid hip spica cast

Correct Answer & Explanation

. Adjust the anterior straps to increase flexion

Explanation

Absent active knee extension indicates a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The harness should be discontinued immediately to allow the nerve to recover.

Question 2651

Topic: Pediatric Hip
A 6-year-old boy presents with a limp and hip pain. Radiographs demonstrate Legg-Calve-Perthes disease with >50% lateral pillar collapse (Herring Group C). According to the literature, which of the following best describes the expected outcome?
. Excellent outcome regardless of treatment
. Poor outcome regardless of treatment in this age group
. Significant benefit from varus derotational osteotomy
. Complete head revascularization within 3 months
. Benefit from conservative management with a Scottish Rite brace

Correct Answer & Explanation

. Poor outcome regardless of treatment in this age group

Explanation

According to the Herring lateral pillar classification, patients over 8 years with Group B/C have better outcomes with surgery. However, Group C hips (regardless of age) generally have poor outcomes, and surgical containment does not significantly alter the natural history.

Question 2652

Topic: Pediatric Upper Extremity & Spine

A 5-year-old boy sustains a completely displaced extension-type supracondylar fracture of the humerus. On examination, the hand is pink and warm, but the radial pulse is absent. After urgent closed reduction and percutaneous pinning, the hand remains pink and warm, but the radial pulse remains non-palpable. What is the most appropriate next step?

. Immediate vascular exploration
. Arteriography
. Observation and admission
. Administration of intra-arterial vasodilators
. Revision of the reduction

Correct Answer & Explanation

. Immediate vascular exploration

Explanation

In a pulseless, pink, and well-perfused hand following a completely displaced supracondylar fracture, observation is the standard of care if perfusion remains intact after reduction and pinning. Vascular exploration is reserved for a pulseless, white (ischemic) hand.

Question 2653

Topic: Pediatric Upper Extremity & Spine

A 13-year-old premenarchal girl presents with adolescent idiopathic scoliosis. Radiographs demonstrate a right thoracic curve of 55 degrees and a Risser stage of 0. Which of the following is the most appropriate treatment?

. Observation with repeat radiographs in 6 months
. Thoracolumbosacral orthosis (TLSO) for 23 hours a day
. Nighttime bending brace
. Posterior spinal fusion with instrumentation
. Anterior tethering procedure

Correct Answer & Explanation

. Observation with repeat radiographs in 6 months

Explanation

A curve of 55 degrees in a skeletally immature patient (Risser 0, premenarchal) has a very high risk of progression. Posterior spinal fusion with instrumentation is the standard treatment for curves >50 degrees.

Question 2654

Topic: 4. Pediatrics

A 7-month-old infant is brought to the emergency department with a swollen right thigh. Radiographs reveal a spiral fracture of the femoral shaft. The parents state the child caught his leg in the crib rails. What is the most critical next step in management?

. Immediate spica casting
. Application of a Pavlik harness
. Skeletal survey and notification of child protective services
. Bone density scan to rule out osteogenesis imperfecta
. Open reduction and flexible intramedullary nailing

Correct Answer & Explanation

. Immediate spica casting

Explanation

A spiral femur fracture in a non-ambulatory infant is highly suspicious for non-accidental trauma (child abuse). The most critical next step is a skeletal survey and involvement of child protective services.

Question 2655

Topic: 4. Pediatrics

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the left hip. The parents report that the child has stopped kicking the left leg. On examination, the left knee remains actively flexed, but the infant does not actively extend it. Patellar reflex is absent on the left. What is the most appropriate next step in management?

. Perform an immediate open reduction
. Adjust the anterior strap to decrease hip abduction
. Adjust the anterior strap to decrease hip flexion
. Switch the patient to a rigid hip spica cast
. Order an urgent MRI of the lumbar spine

Correct Answer & Explanation

. Perform an immediate open reduction

Explanation

The scenario describes a femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness that manifests as an inability to extend the knee. The appropriate management is to temporarily remove the harness or adjust the anterior straps to decrease the degree of hip flexion, allowing the nerve to recover.

Question 2656

Topic: 4. Pediatrics

A 6-year-old boy falls from the monkey bars and sustains a significantly displaced extension-type supracondylar humerus fracture. Prior to reduction, the examiner notes that the child cannot flex the interphalangeal joint of the thumb or the distal interphalangeal joint of the index finger. Which of the following nerves is most likely injured?

. Radial nerve
. Ulnar nerve
. Anterior interosseous nerve
. Posterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Radial nerve

Explanation

The anterior interosseous nerve (AIN), a branch of the median nerve, is the most commonly injured nerve in extension-type pediatric supracondylar humerus fractures. Injury clinically presents with the inability to flex the IP joint of the thumb and DIP joint of the index finger, disrupting the normal "OK" sign.

Question 2657

Topic: Pediatric Hip

A 13-year-old obese boy presents to the emergency department with sudden, severe left hip pain after tripping on a step. He is entirely unable to bear weight on the left leg, even with the use of crutches. Radiographs demonstrate a displaced slipped capital femoral epiphysis (SCFE). Which of the following represents the most significant complication risk specific to this presentation compared to a patient who can bear weight?

. Chondrolysis
. Osteonecrosis (avascular necrosis)
. Femoroacetabular impingement
. Contralateral SCFE development
. Premature physeal closure

Correct Answer & Explanation

. Chondrolysis

Explanation

The inability to bear weight even with assistive devices clinically defines an unstable SCFE. Unstable SCFE carries a significantly higher risk of osteonecrosis (up to 47%) compared to stable SCFE, necessitating careful surgical management and often joint decompression.

Question 2658

Topic: Pediatric Hip

A 6-week-old infant with developmental dysplasia of the hip (DDH) is placed in a Pavlik harness. Two weeks later, the parents report that the infant is no longer actively kicking the right leg. On examination, the knee lacks active extension. Which of the following is the most likely cause of this complication?

. Excessive abduction in the anterior straps
. Excessive flexion in the anterior straps
. Inadequate flexion in the posterior straps
. Avascular necrosis of the femoral head
. Transient synovitis

Correct Answer & Explanation

. Excessive abduction in the anterior straps

Explanation

Excessive flexion in the anterior straps of a Pavlik harness (typically >120 degrees) can compress the femoral nerve against the inguinal ligament, leading to a transient femoral nerve palsy. The harness should be temporarily discontinued or adjusted.

Question 2659

Topic: Pediatric Upper Extremity & Spine

A 5-year-old boy sustains a completely displaced, extension-type supracondylar humerus fracture. Upon presentation, his hand is pink and well-perfused, but the radial pulse is absent. Following closed reduction and percutaneous pinning, the fracture is perfectly aligned, but the radial pulse remains absent while the hand remains pink. What is the most appropriate next step in management?

. Immediate exploration of the brachial artery
. Removal of the pins and open reduction
. Observation and hospital admission for close neurovascular monitoring
. Performance of a sympathectomy
. Obtain an urgent CT angiogram of the upper extremity

Correct Answer & Explanation

. Immediate exploration of the brachial artery

Explanation

In a 'pulseless, pink' hand following adequate reduction and stabilization of a supracondylar humerus fracture, observation is appropriate. Collateral circulation provides adequate perfusion, and the brachial artery spasm usually resolves over 24-48 hours.

Question 2660

Topic: Pediatric Hip

A 2-year-old girl presents with a limp. Radiographs reveal a previously undiagnosed left-sided developmental dysplasia of the hip (DDH) with complete dislocation. What is the most appropriate definitive management?

. Application of a Pavlik harness
. Closed reduction and spica casting
. Open reduction, capsulorrhaphy, and pelvic osteotomy
. Botulinum toxin injection to the adductors
. Wait until skeletal maturity for a total hip arthroplasty

Correct Answer & Explanation

. Application of a Pavlik harness

Explanation

In a child over 18-24 months of age with a completely dislocated hip, closed reduction is rarely successful or stable. Open reduction combined with a pelvic osteotomy (and sometimes a femoral shortening osteotomy) is indicated to address secondary acetabular dysplasia.

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