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4. Pediatrics MCQs

Practice Set 125 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 2481

Topic: Pediatric Hip

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). After 1 week, the mother notes the child is no longer kicking her right leg, and the knee rests in extension. What is the most likely cause?

. Obturator nerve palsy
. Femoral nerve palsy
. Sciatic nerve palsy
. Avascular necrosis of the femoral head
. Transient synovitis

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion of the hips in a Pavlik harness can compress the femoral nerve, leading to a transient femoral nerve palsy, indicated by a lack of active knee extension. The harness should be temporarily removed or adjusted (flexion reduced) to resolve the palsy.

Question 2482

Topic: Pediatric Upper Extremity & Spine

Which of the following factors indicates the highest risk for curve progression in a patient with Adolescent Idiopathic Scoliosis (AIS)?

. Male gender
. Risser 4
. Peak height velocity
. Thoracolumbar curve pattern
. Closed triradiate cartilage

Correct Answer & Explanation

. Peak height velocity

Explanation

The highest risk for curve progression in AIS occurs during the period of peak height velocity. Skeletal immaturity (e.g., Risser 0, open triradiate cartilage), female gender, and larger initial curve magnitudes are also significant risk factors.

Question 2483

Topic: Pediatric Upper Extremity & Spine

In the Lenke classification for Adolescent Idiopathic Scoliosis, how is a structural minor curve defined on supine side-bending radiographs?

. The Cobb angle fails to reduce to less than 25 degrees
. The Cobb angle reduces to exactly 10 degrees
. Vertebral rotation remains greater than Grade II
. Regional kyphosis exceeds 40 degrees
. The apex of the curve fails to cross the midline

Correct Answer & Explanation

. The Cobb angle fails to reduce to less than 25 degrees

Explanation

A minor curve is considered structural in the Lenke classification if it does not bend out to less than 25 degrees on supine side-bending radiographs. Additionally, regional kyphosis greater than +20 degrees also classifies a curve as structural.

Question 2484

Topic: Pediatric Hip

A 12-year-old girl with a history of DDH treated with closed reduction at infancy presents with a limp. Radiographs show a shortened, widened femoral neck and an enlarged, flat femoral head. This deformity is most likely a sequela of which complication?

. Septic arthritis
. Unrecognized slipped capital femoral epiphysis
. Missed acetabular dysplasia
. Iatrogenic avascular necrosis
. Legg-Calve-Perthes disease

Correct Answer & Explanation

. Iatrogenic avascular necrosis

Explanation

The classic radiographic findings of coxa magna, coxa brevis, and a flat femoral head in a patient with a history of DDH treatment are indicative of iatrogenic avascular necrosis. This is typically sustained during early immobilization, often due to excessive hip abduction.

Question 2485

Topic: Pediatric Hip

A 6-month-old female presents with an asymmetric thigh crease. An AP pelvis radiograph is obtained. Which of the following acetabular index measurements is considered normal for this age?

. 10 degrees
. 22 degrees
. 35 degrees
. 42 degrees
. 50 degrees

Correct Answer & Explanation

. 22 degrees

Explanation

The normal acetabular index in a 6-month-old is generally less than 25 degrees. Values greater than 28-30 degrees are highly suspicious for developmental dysplasia of the hip requiring intervention.

Question 2486

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal girl (Risser 0) is diagnosed with Adolescent Idiopathic Scoliosis. Her right thoracic curve measures 32 degrees. What is the most appropriate recommended management?

. Observation with radiographs in 6 months
. Physical therapy and Schroth exercises alone
. Full-time TLSO bracing
. Posterior spinal fusion
. Anterior vertebral body tethering

Correct Answer & Explanation

. Full-time TLSO bracing

Explanation

Bracing is indicated in skeletally immature patients (Risser 0-2, premenarchal) with curve magnitudes between 25 and 45 degrees. A TLSO worn at least 16-18 hours a day has been shown to significantly decrease the risk of curve progression to surgical magnitude.

Question 2487

Topic: Pediatric Hip

A 4-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up exam, she exhibits absent active knee extension on the treated side. What is the most likely cause of this finding?

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

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion of the hips in a Pavlik harness can lead to femoral nerve palsy, presenting as decreased active knee extension. The harness must be adjusted or temporarily discontinued until full nerve function recovers.

Question 2488

Topic: Pediatric Upper Extremity & Spine

A 13-year-old premenarchal girl presents with a right thoracic adolescent idiopathic scoliosis. Standing AP radiographs demonstrate a Cobb angle of 32 degrees. Her Risser stage is 1. What is the most appropriate management?

. Observation and repeat radiograph in 6 months
. Physical therapy and core strengthening
. Night-time only bending brace
. Full-time TLSO bracing
. Posterior spinal fusion

Correct Answer & Explanation

. Full-time TLSO bracing

Explanation

Full-time TLSO bracing is indicated for growing children (premenarchal, Risser 0-2) with a Cobb angle between 25 and 45 degrees. Clinical trials have proven that full-time bracing significantly decreases the risk of curve progression to the surgical threshold.

Question 2489

Topic: Pediatric Hip

An 18-month-old girl presents with a painless limp and delayed walking. Examination reveals asymmetric thigh folds and a positive Galeazzi sign. Radiographs confirm a unilateral dislocated hip. What is the most appropriate initial treatment?

. Pavlik harness application
. Rigid abduction orthosis
. Closed reduction and spica casting
. Open reduction and pelvic osteotomy
. Observation until age 3

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

For DDH presenting between 6 and 18 months of age, closed reduction and spica casting under general anesthesia is the standard first-line treatment. A Pavlik harness is ineffective at this age due to infant size and mobility.

Question 2490

Topic: Pediatric Hip

On an AP pelvis radiograph of a 6-month-old evaluated for DDH, the proximal femoral metaphysis is located in the upper outer quadrant formed by Hilgenreiner's and Perkin's lines. What does this radiographic finding indicate?

. Normal hip development
. Slipped capital femoral epiphysis
. Acetabular retroversion
. Hip dislocation
. Coxa vara

Correct Answer & Explanation

. Hip dislocation

Explanation

Perkin's line (vertical) and Hilgenreiner's line (horizontal) divide the hip into quadrants. In a normal hip, the medial beak of the metaphysis is in the lower inner quadrant; presence in the upper outer quadrant signifies a dislocated hip.

Question 2491

Topic: 4. Pediatrics

A 7-month-old infant is brought to the emergency department with a spiral midshaft femur fracture. The parents state the child rolled off a low couch. What is the most appropriate next step in management?

. Discharge in a Pavlik harness with orthopedic follow-up in 1 week
. Perform a skeletal survey and consult child protective services
. Immediate flexible intramedullary nailing
. Application of a hip spica cast and routine discharge
. Obtain a DEXA scan to rule out osteogenesis imperfecta

Correct Answer & Explanation

. Perform a skeletal survey and consult child protective services

Explanation

A femur fracture in a non-ambulatory infant is highly suspicious for non-accidental trauma (child abuse). A complete skeletal survey and consultation with child protective services are mandatory to ensure the child's safety before definitive fracture management.

Question 2492

Topic: 4. Pediatrics
An ultrasound of a 6-week-old infant's hip reveals a rounded bony promontory, an alpha angle of 48 degrees, and a beta angle of 60 degrees. According to the Graf classification, what is the best description of this hip?
. Graf Type I (Normal)
. Graf Type II (Dysplastic)
. Graf Type III (Subluxated)
. Graf Type IV (Dislocated)
. Graf Type V (Teratologic)

Correct Answer & Explanation

. Graf Type II (Dysplastic)

Explanation

A Graf Type II hip is characterized by an alpha angle between 43 and 59 degrees, indicating mild dysplasia or physiologic delay. An alpha angle greater than 60 degrees is considered normal (Type I).

Question 2493

Topic: Pediatric Upper Extremity & Spine

In the Lenke classification for Adolescent Idiopathic Scoliosis, what radiographic criterion defines a "structural" minor curve that must be included in the operative fusion construct?

. The curve measures > 10 degrees on a standing AP radiograph
. The curve measures > 20 degrees on a standing AP radiograph
. The curve fails to correct to < 25 degrees on lateral bending radiographs
. The curve fails to correct to < 10 degrees on lateral bending radiographs
. The curve is associated with a kyphosis > 10 degrees

Correct Answer & Explanation

. The curve fails to correct to < 25 degrees on lateral bending radiographs

Explanation

The Lenke classification defines a minor curve as structural if it does not correct to less than 25 degrees on side-bending radiographs (or if there is a regional kyphosis of at least 20 degrees). Structural curves generally must be included in the fusion.

Question 2494

Topic: 4. Pediatrics

You are performing retrograde titanium elastic nailing for a pediatric femur fracture. To achieve optimal three-point fixation and biomechanical stability, how should the nails be contoured and positioned within the canal?

. Contoured into a C-shape and placed with apices facing each other
. Contoured into a C-shape with apices facing opposite directions to create an O-shape
. Kept perfectly straight to maintain maximum cortical contact
. Placed antegrade to avoid damage to the distal femoral physis
. Crossed exactly at the level of the fracture site

Correct Answer & Explanation

. Contoured into a C-shape with apices facing opposite directions to create an O-shape

Explanation

Elastic nails should be pre-bent into a C-shape and inserted such that the apices face in opposite directions, creating an O-shape inside the medullary canal. This provides maximum three-point fixation and rotational stability at the fracture site.

Question 2495

Topic: Pediatric Hip

What is the most critical technical risk factor for the development of iatrogenic avascular necrosis (AVN) of the femoral head during closed reduction and spica casting for DDH?

. Hip extension during the initial reduction maneuver
. Immobilization of the hip in extreme abduction (>60 degrees)
. Inadequate duration of cast immobilization (less than 6 weeks)
. Bilateral hip involvement necessitating a bilateral spica cast
. Use of fiberglass cast material instead of plaster

Correct Answer & Explanation

. Immobilization of the hip in extreme abduction (>60 degrees)

Explanation

Immobilizing the hip in excessive abduction (greater than 60 degrees, the "frog-leg" position) places severe tension on the medial circumflex femoral artery. This is the most significant preventable risk factor for iatrogenic AVN in DDH treatment.

Question 2496

Topic: 4. Pediatrics

Figure 17 shows the AP radiograph of a 5-year old child who has mild short stature and a painless bilateral gluteus medius lurch. Initial work-up should include

. a bone scan.
. a skeletal survey.
. MRI of the hips.
. CT of the hips.
. a CBC count and a C-reactive protein.

Correct Answer & Explanation

. a skeletal survey.

Explanation

Bilateral flattening of the femoral heads suggests multiple epiphyseal dysplasia; therefore, a skeletal survey is indicated to look for involvement of other epiphyses. Unilateral flattening of the femoral head would suggest Legg-Perthes disease. Sponseller PD: Skeletal dysplasias, in Morrissy RT, Weinstein SL (eds): Lovell and Winter's Pediatric Orthopaedics, ed 5. Philadelphia, PA, Lippincott Williams & Wilkins, 2001, pp 269-270.

Question 2497

Topic: Pediatric Hip

A 6-week-old female born breech presents for evaluation of developmental dysplasia of the hip (DDH). Ultrasound of the hips reveals an alpha angle of 45 degrees and a beta angle of 78 degrees on the left side. The right hip is normal. What is the most appropriate next step in management?

. Observation with repeat ultrasound in 4 weeks
. Double diapering
. Pavlik harness application
. Closed reduction and spica casting
. Open reduction

Correct Answer & Explanation

. Pavlik harness application

Explanation

An alpha angle less than 60 degrees and a beta angle greater than 55 degrees (Graf Type IIc or worse) indicate significant acetabular dysplasia. The Pavlik harness is the gold standard for treatment of DDH in infants younger than 6 months of age.

Question 2498

Topic: Pediatric Hip

A 2-year-old female who recently immigrated is brought to the clinic for a noticeable limp and leg length discrepancy. Radiographs reveal an untreated, high-riding developmental dislocation of the right hip. What is the most appropriate definitive management?

. Pavlik harness application
. Hip abduction orthosis
. Closed reduction and spica casting
. Open reduction and pelvic osteotomy
. Proximal femoral varus derotational osteotomy alone

Correct Answer & Explanation

. Open reduction and pelvic osteotomy

Explanation

In a child older than 18 to 24 months with an untreated DDH, closed reduction has a high failure and avascular necrosis rate. Open reduction with a concomitant pelvic osteotomy (e.g., Salter or Pemberton) is generally required to address the secondary capsular and acetabular changes.

Question 2499

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department with severe right thigh pain after a minor slip on the ice. He is completely unable to bear weight on the right leg. Radiographs demonstrate a slipped capital femoral epiphysis (SCFE). Which of the following complications is he at the greatest risk of developing?

. Chondrolysis
. Osteonecrosis of the femoral head
. Deep space infection
. Premature osteoarthritis
. Subspine impingement

Correct Answer & Explanation

. Osteonecrosis of the femoral head

Explanation

The patient's inability to bear weight even with crutches categorizes this as an unstable SCFE. Unstable slips carry a significantly higher risk of osteonecrosis (avascular necrosis), reaching up to nearly 50% in some series.

Question 2500

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal female presents for a routine evaluation. Radiographs reveal a right thoracic adolescent idiopathic scoliosis (AIS) curve measuring 35 degrees. Her Risser stage is 0. What is the most appropriate management?

. Observation and follow-up in 6 months
. Physical therapy focusing on core strengthening
. Thoracolumbosacral orthosis (TLSO) bracing
. Vertebral body tethering
. Posterior spinal fusion

Correct Answer & Explanation

. Thoracolumbosacral orthosis (TLSO) bracing

Explanation

This patient has significant remaining growth (premenarchal, Risser 0) and a progressive curve between 25 and 45 degrees. TLSO bracing is indicated to halt progression and decrease the likelihood of requiring surgical intervention.

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