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4. Pediatrics MCQs

Practice Set 124 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 2461

Topic: Pediatric Hip

A 6-week-old infant undergoes a screening ultrasound for developmental dysplasia of the hip (DDH) due to a breech presentation. The report mentions the alpha and beta angles according to the Graf classification. What anatomical structure does the alpha angle primarily evaluate?

. The cartilaginous acetabular roof
. The bony acetabular roof
. The femoral head sphericity
. The degree of labral inversion
. The triradiate cartilage width

Correct Answer & Explanation

. The bony acetabular roof

Explanation

In the Graf ultrasound classification for DDH, the alpha angle measures the concavity and depth of the bony acetabular roof. The beta angle measures the cartilaginous roof.

Question 2462

Topic: Pediatric Hip

A 13-year-old boy whose body mass index (BMI) is in the 95th percentile presents with a 4-month history of vague left knee pain. Examination of the knee shows no effusion, and there is full, painless range of motion. Examination of the left hip reveals obligatory external rotation when the hip is flexed to 90 degrees. What is the most appropriate next step in diagnosis?

. MRI of the left knee
. AP and frog-leg lateral radiographs of the pelvis
. Diagnostic ultrasound of the left knee
. Reassurance and nonsteroidal anti-inflammatory drugs
. Technetium-99m bone scan

Correct Answer & Explanation

. AP and frog-leg lateral radiographs of the pelvis

Explanation

This classic presentation (knee pain, obesity, obligatory external rotation with hip flexion) is highly suspicious for a Slipped Capital Femoral Epiphysis (SCFE). Pain is often referred to the knee via the obturator nerve, making AP and frog-leg lateral pelvis radiographs mandatory.

Question 2463

Topic: 4. Pediatrics

A newborn with arthrogryposis multiplex congenita is noted to have bilateral rigid, dislocated hips on examination. Ultrasound confirms bilateral high dislocations. What is the most appropriate initial management for these hips?

. Immediate application of a Pavlik harness
. Immediate closed reduction and spica casting
. Observation in the neonatal period, with planned open reduction later if walking is anticipated
. Bilateral femoral nerve blocks to reduce tone
. Serial casting of the hips in flexion and abduction

Correct Answer & Explanation

. Observation in the neonatal period, with planned open reduction later if walking is anticipated

Explanation

Teratologic hip dislocations (seen in arthrogryposis or severe syndromic conditions) are stiff and do not respond to Pavlik harness treatment. The standard of care is observation during early infancy, followed by open reduction (often with osteotomies) when the child is older and approaching walking age.

Question 2464

Topic: Pediatric Hip

A 14-year-old girl who underwent in situ pinning for a stable left SCFE 6 months ago presents with increasing left hip stiffness and pain. Radiographs demonstrate a diffuse 50% loss of the joint space in the left hip compared to the right, with no signs of hardware failure. What is the most likely diagnosis?

. Avascular necrosis (AVN)
. Chondrolysis
. Septic arthritis
. Implant failure
. Heterotopic ossification

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is characterized by diffuse joint space narrowing, severe stiffness, and pain after SCFE treatment. It is highly associated with unrecognized pin penetration into the hip joint during surgical fixation.

Question 2465

Topic: Pediatric Hip

While performing a closed reduction and spica casting for a 9-month-old with developmental dysplasia of the hip (DDH), the surgeon evaluates the 'safe zone' of Ramsey. The hip dislocates in adduction. To minimize the risk of iatrogenic avascular necrosis (AVN) of the femoral head, what position must the surgeon strictly avoid when applying the cast?

. Extreme hip flexion (greater than 100 degrees)
. Extreme hip internal rotation
. Extreme hip abduction (frog-leg position)
. Extreme hip adduction
. Knee flexion of 90 degrees

Correct Answer & Explanation

. Extreme hip abduction (frog-leg position)

Explanation

The safe zone of Ramsey lies between the angle of adduction where the hip dislocates and the angle of maximum abduction. Casting in extreme or forced abduction (the 'frog-leg' position) compromises the retinacular vessels, dramatically increasing the risk of avascular necrosis (AVN).

Question 2466

Topic: 4. Pediatrics

A 4-week-old infant with developmental dysplasia of the hip (DDH) has been treated in a Pavlik harness for 1 week. The mother brings the child in, noting that the infant is no longer actively kicking or extending the knee on the affected side. What is the most appropriate next step in management?

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

Correct Answer & Explanation

. Discontinue the harness and observe

Explanation

The clinical presentation describes a femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness. The most appropriate management is to remove or loosen the harness and observe until nerve function recovers.

Question 2467

Topic: Pediatric Upper Extremity & Spine
A 12-year-old pre-menarcheal girl presents with a right thoracic adolescent idiopathic scoliosis (AIS). Her Risser stage is 0, and her curve measures 32 degrees on a standing PA radiograph. What is the most evidence-based management strategy?
. Observation with serial radiographs every 6 months
. Thoracolumbosacral orthosis (TLSO) bracing for 16-23 hours daily
. Nighttime only bending brace
. Immediate posterior spinal fusion
. Vertebral body tethering (VBT)

Correct Answer & Explanation

. Thoracolumbosacral orthosis (TLSO) bracing for 16-23 hours daily

Explanation

The patient is a growing child (Risser 0, pre-menarcheal) with a curve between 25 and 45 degrees. According to the BRAIST trial, full-time bracing (TLSO for 16-23 hours/day) is highly effective in preventing curve progression to surgical thresholds in this population.

Question 2468

Topic: Pediatric Hip

A 7-month-old girl presents for her first pediatric orthopedic evaluation and is diagnosed with bilateral DDH. Ultrasound confirms bilateral dislocated hips that are irreducible on dynamic examination. What is the most appropriate initial treatment?

. Pavlik harness application
. Closed reduction and spica casting
. Open reduction with bilateral capsulorrhaphy
. Bilateral Salter innominate osteotomies
. Bilateral femoral shortening osteotomies

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

The Pavlik harness has a high failure rate in children older than 6 months and in those with irreducible dislocations. Closed reduction with spica casting under anesthesia is the most appropriate initial intervention for late-presenting DDH at this age.

Question 2469

Topic: 4. Pediatrics

A 6-week-old female infant is evaluated for DDH. Coronal ultrasound of the right hip reveals an alpha angle of 55 degrees and a beta angle of 65 degrees. According to the Graf classification, what is the appropriate management?

. No follow-up required
. Observation with repeat ultrasound in 4 weeks
. Immediate application of a Pavlik harness
. Closed reduction and spica casting
. Abduction bracing for 23 hours a day

Correct Answer & Explanation

. Observation with repeat ultrasound in 4 weeks

Explanation

An alpha angle between 50 and 59 degrees in a child younger than 3 months represents a Graf Type IIa hip (physiologic immaturity). The standard of care is observation with a follow-up ultrasound, as the majority will resolve spontaneously.

Question 2470

Topic: 4. Pediatrics
A 10-year-old boy with a history of DDH treated by closed reduction at age 1 presents for follow-up. Radiographs demonstrate a progressive coxa valga deformity and a short femoral neck, but the medial physis remains open. According to the Kalamchi-MacEwen classification, what type of vascular insult occurred?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type II

Explanation

The Kalamchi-MacEwen classification describes AVN after DDH treatment. Type II involves damage to the lateral portion of the physis, resulting in a progressive valgus deformity of the femoral head and neck.

Question 2471

Topic: 4. Pediatrics

A 10-month-old infant who is not yet cruising or walking presents to the emergency department with a swollen, painful thigh. Radiographs reveal a closed spiral fracture of the mid-diaphyseal femur. What is the most critical next step in management?

. DEXA scan to rule out osteogenesis imperfecta
. Child protective services consultation and skeletal survey
. Genetic testing for collagen disorders
. Immediate rigid intramedullary nailing
. Reassurance and discharge with a soft splint

Correct Answer & Explanation

. Child protective services consultation and skeletal survey

Explanation

Femur fractures in non-ambulatory infants are highly suspicious for non-accidental trauma (child abuse). The standard of care mandates immediate involvement of child protective services and a full skeletal survey to identify other hidden injuries.

Question 2472

Topic: Pediatric Hip

A 5-year-old girl with residual DDH undergoes preoperative planning for a pelvic osteotomy. The chosen technique is an incomplete pericapsular osteotomy that hinges on the triradiate cartilage, dynamically reducing the volume of the acetabulum. Which osteotomy is described?

. Salter
. Pemberton
. Steel
. Chiari
. Dega

Correct Answer & Explanation

. Pemberton

Explanation

The Pemberton osteotomy is an incomplete pericapsular procedure that hinges at the triradiate cartilage. By changing the shape of the acetabular roof, it inherently reduces the acetabular volume, making it highly effective for true dysplastic, capacious acetabula.

Question 2473

Topic: 4. Pediatrics

A 4-week-old infant sustains a closed midshaft femur fracture after a roll-over injury in a stroller. What is the most appropriate initial management?

. Spica casting
. Pavlik harness
. Elastic stable intramedullary nailing
. Submuscular plating
. Traction

Correct Answer & Explanation

. Pavlik harness

Explanation

The Pavlik harness is the standard of care for infants younger than 6 months with femur fractures. It provides excellent outcomes, is easier to apply than a spica cast, and has lower rates of skin complications.

Question 2474

Topic: 4. Pediatrics

A 7-year-old girl sustains a Delbet type II (transcervical) femoral neck fracture. Despite urgent closed reduction and internal fixation, she is at the highest risk for which of the following complications?

. Nonunion
. Avascular necrosis (AVN)
. Chondrolysis
. Premature physeal closure
. Coxa vara

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

AVN is the most common and devastating complication of pediatric femoral neck fractures. The risk is highest with Delbet type I and type II fractures due to disruption of the intracapsular blood supply.

Question 2475

Topic: Pediatric Hip

A 4-month-old girl is being treated in a Pavlik harness for developmental dysplasia of the hip (DDH). Her parents report that she is no longer actively extending her right knee. What is the most likely cause of this complication?

. Obturator nerve palsy from excessive abduction
. Femoral nerve palsy from excessive hip flexion
. Sciatic nerve palsy from excessive hip extension
. Superior gluteal nerve palsy from harness straps
. Avascular necrosis of the femoral head

Correct Answer & Explanation

. Femoral nerve palsy from excessive hip flexion

Explanation

Femoral nerve palsy in a Pavlik harness is caused by excessive hip flexion, leading to nerve impingement against the inguinal ligament. It usually resolves completely after temporarily releasing the anterior flexion straps.

Question 2476

Topic: 4. Pediatrics

A 6-week-old infant undergoes hip ultrasonography for suspected developmental dysplasia. The alpha angle is measured at 62 degrees and the beta angle is 50 degrees. According to the Graf classification, what is the appropriate management?

. Pavlik harness application
. Closed reduction and spica casting
. Rigid abduction bracing
. Observation and no treatment
. Surgical open reduction

Correct Answer & Explanation

. Observation and no treatment

Explanation

An alpha angle greater than 60 degrees and a beta angle less than 55 degrees indicates a Graf Type I (normal) hip. No treatment is necessary, and routine pediatric care should continue.

Question 2477

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal girl (Risser 0) has a right thoracic adolescent idiopathic scoliosis (AIS) curve of 35 degrees. Which of the following is the most appropriate management?

. Observation with radiographs in 6 months
. Physical therapy and Schroth exercises
. Thoracolumbosacral orthosis (TLSO) bracing
. Posterior spinal fusion
. Anterior tethering procedure

Correct Answer & Explanation

. Thoracolumbosacral orthosis (TLSO) bracing

Explanation

Bracing is indicated for skeletally immature patients (Risser 0-2) with idiopathic curves between 25 and 45 degrees. A TLSO brace significantly decreases the risk of curve progression to the surgical threshold.

Question 2478

Topic: 4. Pediatrics

A 9-month-old infant undergoes closed reduction and spica casting for late-diagnosed DDH. Postoperatively, the hip is noted to be immobilized in 65 degrees of abduction. What complication is the child at highest risk for?

. Redislocation
. Femoral nerve palsy
. Avascular necrosis (AVN)
. Acetabular dysplasia
. Coxa magna

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

Immobilizing the hip in excessive abduction (greater than 60 degrees) dramatically increases the risk of avascular necrosis of the femoral head. This is due to compression of the extracapsular epiphyseal vessels.

Question 2479

Topic: Pediatric Hip

An 18-month-old girl presents with untreated developmental dysplasia of the hip (DDH). She has a positive Galeazzi sign and limited hip abduction. What is the most appropriate initial intervention?

. Pavlik harness
. Closed reduction and spica casting
. Open reduction and spica casting
. Femoral shortening osteotomy
. Observation until age 3

Correct Answer & Explanation

. Open reduction and spica casting

Explanation

For DDH presenting at 18 months or older, open reduction is generally the initial treatment of choice. Closed reduction at this age has a high failure rate and an increased risk of AVN.

Question 2480

Topic: 4. Pediatrics

In an infant with idiopathic scoliosis, which radiographic parameter most strongly predicts the likelihood of curve progression?

. Cobb angle greater than 10 degrees
. Risser sign of 0
. Rib-vertebral angle difference (RVAD) greater than 20 degrees
. Apical vertebral rotation of Grade I
. Presence of a hemivertebra

Correct Answer & Explanation

. Rib-vertebral angle difference (RVAD) greater than 20 degrees

Explanation

Mehta's rib-vertebral angle difference (RVAD) is the primary prognostic indicator in infantile idiopathic scoliosis. An RVAD greater than 20 degrees strongly predicts progressive deformity rather than spontaneous resolution.

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