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4. Pediatrics MCQs

Practice Set 22 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 421

Topic: 4. Pediatrics

The parameter most often recommended to follow the reciprocal relationship of the femoral head to the acetabulum in patients with cerebral palsy is known as the:

. Migration index
. Epiphyseal extrusion index
. Stulberg index
. Acetabular index
. Tonnis index

Correct Answer & Explanation

. Migration index

Explanation

The migration index (of Reimer) is most commonly used to track the femoral-acetabular relationship in patients with cerebral palsy because it most accurately portrays the progressive migration of the femoral head that may occur. The acetabular index only measures the acetabular response. The epiphyseal extrusion index is used for patients with Perthes disease (where the epiphysis deforms). The Stulberg index is for late outcome of Perthes, and the Tonnis index is for developmental dysplasia of the hip.

Question 422

Topic: 4. Pediatrics

The upper limit for a normal migration index in young children is less than:

. 0%
. 5%
. 10%
. 25%
. 35%

Correct Answer & Explanation

. 25%

Explanation

The migration index (of Reimer) is the percentage of the femoral head lateral to the Perkins line. The index is used to quantify hip migration in patients with cerebral palsy. It is more useful than the center-edge angle because it is a linear variable angle and because the center of the aspherical, immature femoral head may be hard to accurately identify. The upper limit of a normal migration in young children is listed as 25%.

Question 423

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal female presents with right thoracic idiopathic scoliosis. Radiographs demonstrate a Cobb angle of 30 degrees and a Risser stage of 0. What is the most appropriate management?

. Observation with follow-up in 6 months
. Thoracolumbosacral orthosis (TLSO) bracing for 18 hours per day
. Nighttime bending brace
. Posterior spinal fusion
. Physical therapy and core strengthening

Correct Answer & Explanation

. Thoracolumbosacral orthosis (TLSO) bracing for 18 hours per day

Explanation

Bracing is indicated for skeletally immature patients (Risser 0-2) with idiopathic scoliosis curves between 25 and 45 degrees. A TLSO worn for at least 18 hours daily has been shown to significantly decrease the risk of curve progression to the surgical threshold.

Question 424

Topic: 4. Pediatrics

A 3-year-old child is diagnosed with congenital scoliosis secondary to a fully segmented hemivertebra. Which of the following is the most appropriate routine screening test required in this patient?

. Echocardiogram
. Renal ultrasound
. Pulmonary function tests
. Brain MRI
. DEXA scan

Correct Answer & Explanation

. Renal ultrasound

Explanation

Congenital scoliosis is highly associated with genitourinary anomalies (up to 30%), most commonly unilateral kidney. A renal ultrasound is a mandatory screening test in these patients to evaluate for associated defects.

Question 425

Topic: 4. Pediatrics

A 6-year-old boy presents with a completely displaced, extension-type supracondylar humerus fracture. He is unable to flex his interphalangeal joint of the thumb or the distal interphalangeal joint of the index finger. Which nerve is most likely injured?

. Radial nerve
. Ulnar nerve
. Anterior interosseous nerve
. Musculocutaneous nerve
. Recurrent motor branch of median nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type pediatric supracondylar humerus fractures. Injury presents with the inability to make an 'OK' sign, indicating weakness of the flexor pollicis longus and flexor digitorum profundus.

Question 426

Topic: Pediatric Upper Extremity & Spine

According to the Lenke classification for adolescent idiopathic scoliosis, what criteria define a structural proximal thoracic curve?

. Cobb angle > 25 degrees on side-bending radiographs or kyphosis > 20 degrees between T2 and T5
. Cobb angle > 10 degrees on side-bending radiographs
. Apical vertebral rotation > Grade II
. Cobb angle > 25 degrees on AP standing radiograph
. Cobb angle > 20 degrees on side-bending radiographs or lordosis > 10 degrees

Correct Answer & Explanation

. Cobb angle > 25 degrees on side-bending radiographs or kyphosis > 20 degrees between T2 and T5

Explanation

In the Lenke classification, minor curves are considered structural if they do not bend out to less than 25 degrees on side-bending films, or if there is regional kyphosis of at least +20 degrees. For the proximal thoracic curve, the kyphosis is measured between T2 and T5.

Question 427

Topic: Pediatric Upper Extremity & Spine

To prevent the 'crankshaft phenomenon' in a skeletally immature patient with adolescent idiopathic scoliosis (Risser 0, open triradiate cartilages) undergoing posterior spinal fusion, what surgical strategy has historically been indicated?

. Combined anterior and posterior spinal fusion
. Use of pedicle screw only constructs without osteotomies
. Extension of fusion to the sacrum
. Sublaminar wiring techniques
. Postoperative halo-gravity traction

Correct Answer & Explanation

. Combined anterior and posterior spinal fusion

Explanation

The crankshaft phenomenon occurs due to continued anterior vertebral growth after a solid posterior fusion in very immature patients. Historically, a combined anterior (to arrest growth) and posterior fusion was required to prevent this progressive deformity.

Question 428

Topic: Pediatric Upper Extremity & Spine

A 14-year-old pre-menarchal female (Risser 0) presents with a 35-degree right thoracic idiopathic scoliosis curve. What is the most appropriate initial management?

. Observation with serial radiographs every 6 months
. Thoracolumbosacral orthosis (TLSO) bracing
. Posterior spinal fusion with pedicle screw instrumentation
. Anterior vertebral body tethering
. Physiotherapy and core strengthening alone

Correct Answer & Explanation

. Thoracolumbosacral orthosis (TLSO) bracing

Explanation

In a skeletally immature patient (e.g., Risser 0, pre-menarchal) with a progressing idiopathic curve between 25 and 45 degrees, bracing is the standard of care. A TLSO has been shown to be highly effective in preventing curve progression to surgical thresholds.

Question 429

Topic: Pediatric Upper Extremity & Spine

A 12-year-old girl with adolescent idiopathic scoliosis presents with a right thoracic curve of 32 degrees. She is premenarcheal and has a Risser stage of 0. What is the most appropriate management?

. Observation with repeat radiographs in 6 months
. Thoracolumbosacral orthosis (TLSO) bracing for 16-23 hours daily
. Nighttime bending brace only
. Posterior spinal fusion
. Physical therapy and core strengthening

Correct Answer & Explanation

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

Explanation

Bracing is indicated for growing children (Risser 0-2, premenarcheal) with curves between 25 and 45 degrees. A TLSO worn 16-23 hours a day significantly decreases the risk of curve progression to the surgical threshold.

Question 430

Topic: Pediatric Upper Extremity & Spine

According to the Lonstein and Carlson formula, which combination of factors carries the highest risk for curve progression in a patient with idiopathic scoliosis?

. Low Risser sign, chronological age greater than 15, small curve magnitude
. High Risser sign, large curve magnitude, postmenarcheal status
. Low Risser sign, large curve magnitude, chronologically young age
. High Risser sign, small curve magnitude, chronologically young age
. High Risser sign, double major curve, chronologically older age

Correct Answer & Explanation

. Low Risser sign, large curve magnitude, chronologically young age

Explanation

Risk of curve progression in idiopathic scoliosis is highest in young, skeletally immature patients (low Risser sign, premenarcheal) with larger curve magnitudes at the time of presentation.

Question 431

Topic: Pediatric Upper Extremity & Spine
A 5-year-old girl sustains an extension-type Gartland III supracondylar humerus fracture with posteromedial displacement. Which nerve is most commonly injured in this specific displacement pattern?
. Radial nerve
. Median nerve
. Ulnar nerve
. Anterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Radial nerve

Explanation

In posteromedial displacement of extension-type supracondylar humerus fractures, the distal fragment goes medially, leaving the proximal fragment protruding laterally. This lateral spike puts the radial nerve at the highest risk of injury.

Question 432

Topic: Pediatric Upper Extremity & Spine
A 13-year-old girl with adolescent idiopathic scoliosis presents with a 25-degree right thoracic curve. Her Risser stage is 0, and she is premenarcheal. What is the most appropriate initial management?
. Observation with radiographs in 1 year
. Thoracolumbosacral orthosis (TLSO) bracing for 18 hours per day
. Nighttime only rigid bending brace
. Posterior spinal fusion
. Anterior vertebral body tethering

Correct Answer & Explanation

. Thoracolumbosacral orthosis (TLSO) bracing for 18 hours per day

Explanation

For a growing child (Risser 0-2) with an idiopathic curve between 25 and 45 degrees, TLSO bracing for a minimum of 18 hours per day is the standard of care to prevent curve progression. The BRAIST trial demonstrated a dose-dependent success rate with brace wear.

Question 433

Topic: Pediatric Upper Extremity & Spine

In the Lenke classification for adolescent idiopathic scoliosis, a lumbar curve modifier of 'C' indicates that the center sacral vertical line (CSVL) falls in which relation to the apical lumbar vertebra?

. Between the pedicles
. Touches the medial aspect of the apical pedicle
. Falls completely medial to the medial edge of the apical pedicle
. Falls completely lateral to the lateral edge of the apical vertebra
. Intersects the spinous process exactly

Correct Answer & Explanation

. Falls completely medial to the medial edge of the apical pedicle

Explanation

A Lenke 'C' modifier indicates a substantial lumbar curve where the CSVL falls completely medial to the medial border of the apical lumbar pedicle. A 'B' modifier touches the pedicle, and an 'A' modifier falls between the pedicles.

Question 434

Topic: Pediatric Lower Extremity

All of the following conditions may affect lower extremities in children. Which one of the conditions does not have a high incidence of spontaneous improvement:

. Posteromedial bow of the tibia
. C alcaneovalgus foot
. Metatarsus adductus
. Internal tibial torsion
. Anterolateral bowing of the tibia

Correct Answer & Explanation

. Anterolateral bowing of the tibia

Explanation

Anterolateral bowing of the tibia is usually associated with tibial dysplasia and may progress to pseudarthrosis. Anterolateral bowing of the tibia does not resolve in most patients. Posteromedial bowing of the tibia usually resolves, although there may be a residual shortening of the tibia. All of the other conditions often completely resolve.

Question 435

Topic: Pediatric Upper Extremity & Spine

The anterior interosseous nerve enables:

. Sensation and flexion of the thumb and index fingers
. Flexion of the thumb and index fingers
. Flexion of the lateral (ulnar) two fingers
. Flexion and sensation of the ulnar two fingers
. Abduction of the thumb

Correct Answer & Explanation

. Flexion of the thumb and index fingers

Explanation

The anterior interosseous nerve does not carry any sensory fibers. The anterior interosseous nerve enables flexion of the thumb (flexor digitorum pollicis) and index fingers (flexor digitorum profundus). This is the most commonly injured nerve in a supracondylar fracture, and it nearly always spontaneously recovers.

Question 436

Topic: Pediatric Upper Extremity & Spine

Closed reduction without internal fixation is most likely to produce a satisfactory result in which of the following types of supracondylar fracture:

. An intact posterior hinge and 20° of hyperextension
. An intact lateral hinge and 15° of varus
. Posterior and medial translation with no intact hinge
. Posterior and lateral translation with no intact hinge
. Anterior translation with 10° of varus

Correct Answer & Explanation

. An intact posterior hinge and 20° of hyperextension

Explanation

There are many options when treating a supracondylar fracture, but a surgeon should always choose the method with the highest percentage of good results for a given fracture. Answer A describes a type II supracondylar fracture with hyperextension and no varus-valgus displacement. The posterior hinge is intact, and it is relatively simple to reduce the fracture with flexion, immobilizing it at 120°. For the other fractures listed as possible answer choices, the reduction as well as the assessment of reduction is more complex. Therefore, most experts would prefer percutaneous fixation of these fractures once reduced.

Question 437

Topic: 4. Pediatrics

The highest rate of success in restoring growth after physeal bar resection is found in which location:

. Proximal femur
. Distal femur
. Proximal tibia
. Distal tibia
. Proximal humerus

Correct Answer & Explanation

. Distal tibia

Explanation

The highest rate of success after physeal bar resection is found in the distal tibia. The mean growth after resection in the series by Peterson was 93% of that expected, which is greater than the success rates of the other locations. The reasons for this remain speculative but may be due to the more peripheral location of the bar at the ankle, less complex physeal shape, and lower energy of injury. Physeal bars in the proximal femur and humerus are rarely surgically treated.

Question 438

Topic: 4. Pediatrics

Which of the following statements is true regarding congenital pseudarthrosis of the tibia:

. Congenital pseudarthrosis of the tibia is nearly always associated with neurofibromatosis.
. Congenital pseudarthrosis of the tibia usually occurs in the proximal one- third of the tibia.
. Congenital pseudarthrosis of the tibia usually presents with a valgus deformity.
. Congenital pseudarthrosis of the tibia usually presents with an apex- posterior bow.
. The surrounding bone is usually dysplastic.

Correct Answer & Explanation

. The surrounding bone is usually dysplastic.

Explanation

Congenital pseudarthrosis of the tibia is associated with neurofibromatosis in approximately one-half of patients. It usually occurs in the distal portion of the tibia, presents with a varus position, and an apex-anterior bow. The surrounding bone is usually dysplastic, displaying segments of sclerosis, tapering, and/or cystic changes. The fibula is often dysplastic as well.

Question 439

Topic: 4. Pediatrics

Which of the following elements is most critical to the success of the Williams rod procedure (intramedullary rod fixation) for congenital pseudarthrosis of the tibia:

. Fibular fixation
. Leaving the rod across the ankle at the time of surgery
. Prolonged orthotic protection
. Electrical stimulation
. Ultrasound stimulation

Correct Answer & Explanation

. Fibular fixation

Explanation

Fixation of the fibula allows shortening and compression of the tibia, as well as providing mechanical stability. Neither leaving the rod across the ankle nor prolonged orthotic protection beyond the initial postoperative period appears to be essential. Electrical stimulation does not have a quantifiable effect on the success of the procedure. Ultrasound has not been studied in this condition.

Question 440

Topic: 4. Pediatrics

In the absence of surgery, which of the following gait parameters in children with cerebral palsy tends to remain static with increasing age:

. Knee range of motion
. Ankle range of motion
. Normalized walking velocity
. Femoral anteversion
. Knee stiffness

Correct Answer & Explanation

. Femoral anteversion

Explanation

Most parameters of gait deteriorate over time in the absence of intervention in children with cerebral palsy. Knee and ankle range of motion decrease, as does walking velocity when normalized for height. Femoral anteversion remains unchanged. Knee stiffness increases.

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