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4. Pediatrics MCQs

Practice Set 123 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 2441

Topic: 4. Pediatrics

A 4-week-old infant is prescribed a Pavlik harness for developmental dysplasia of the hip. At a follow-up visit, the anterior straps are noted to be adjusted so tightly that the hips are held in 135 degrees of flexion. This excessive flexion puts the infant at greatest risk for which of the following?

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

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion of the hips in a Pavlik harness (>120 degrees) risks femoral nerve palsy. Conversely, excessive forced abduction risks avascular necrosis (AVN) of the femoral head.

Question 2442

Topic: Pediatric Hip

An 11-year-old overweight boy complains of left knee pain. Knee radiographs are unremarkable. An AP pelvis radiograph is obtained.

A line drawn along the superior margin of the left femoral neck fails to intersect any portion of the femoral epiphysis. What is the name of this radiographic line?

. Shenton's line
. Hilgenreiner's line
. Perkin's line
. Klein's line
. Skinner's line

Correct Answer & Explanation

. Klein's line

Explanation

Klein's line is drawn along the superior edge of the femoral neck. In a normal hip, it should intersect the lateral portion of the femoral epiphysis. Failure to do so is highly suggestive of a Slipped Capital Femoral Epiphysis (SCFE).

Question 2443

Topic: Pediatric Hip

Which of the following surgical techniques is the most widely accepted standard to minimize the risk of complications when treating a typical stable Slipped Capital Femoral Epiphysis (SCFE)?

. Forceful closed reduction to anatomic alignment followed by pinning
. In situ fixation with a single central fully threaded screw
. In situ fixation with three parallel pins to maximize rotational control
. Immediate subtrochanteric derotational osteotomy
. Open reduction via surgical dislocation (Dunn procedure) for all stable slips

Correct Answer & Explanation

. In situ fixation with a single central fully threaded screw

Explanation

The gold standard for a typical stable SCFE is in situ fixation using a single, central, partially or fully threaded screw. Forceful reduction increases the risk of AVN, and multiple pins increase the risk of chondrolysis and joint penetration without significant added biomechanical benefit.

Question 2444

Topic: Pediatric Upper Extremity & Spine

In a 12-year-old girl with Adolescent Idiopathic Scoliosis (AIS), which of the following radiographic markers indicates that she is currently at or very near the phase of peak height velocity, representing the highest risk for curve progression?

. Risser stage 4
. Closure of the triradiate cartilage
. Appearance of the iliac apophysis
. Risser stage 5
. Fusion of the proximal humeral physis

Correct Answer & Explanation

. Closure of the triradiate cartilage

Explanation

Closure of the triradiate cartilage typically occurs just before or during the period of peak height velocity. An open triradiate cartilage indicates significant remaining growth and a high risk of curve progression.

Question 2445

Topic: 4. Pediatrics

According to the AAOS Clinical Practice Guidelines, which of the following infants should routinely undergo a screening ultrasound for developmental dysplasia of the hip (DDH) at 6 weeks of age, assuming normal serial physical examinations?

. A male infant with torticollis
. A female infant born in the breech presentation
. A male infant born prematurely at 32 weeks
. A female infant born via cesarean section for fetal distress
. A male infant with metatarsus adductus

Correct Answer & Explanation

. A female infant born in the breech presentation

Explanation

Breech presentation is the most significant single risk factor for DDH. The AAOS strongly recommends routine ultrasound screening at 4 to 6 weeks for infants born in the breech position, particularly females, even if physical exams are normal.

Question 2446

Topic: Pediatric Hip

A 4-week-old female is placed in a Pavlik harness for developmental dysplasia of the hip (DDH). Two weeks later, the parents report that the child has stopped kicking her right leg. On exam, there is an absent quadriceps reflex and no active knee extension. What is the most appropriate next step in management?

. Continue harness but loosen the anterior straps
. Discontinue the harness and observe
. Switch to a rigid abduction orthosis
. Proceed to closed reduction and spica casting
. Perform immediate ultrasound to check for femoral head AVN

Correct Answer & Explanation

. Discontinue the harness and observe

Explanation

This patient has a femoral nerve palsy, the most common neurologic complication of the Pavlik harness, typically caused by hyperflexion. The harness should be discontinued and the patient observed; function almost always returns within a few weeks.

Question 2447

Topic: Pediatric Hip

A 13-year-old obese male presents with 2 days of severe left hip pain and an inability to bear weight after a minor fall. Radiographs show a severe slipped capital femoral epiphysis (SCFE). He is treated with an urgent gentle closed reduction and pinning. Which of the following is the most significant risk associated with this specific presentation and intervention?

. Chondrolysis
. Avascular necrosis (AVN)
. Femoroacetabular impingement (FAI)
. Contralateral slip
. Septic arthritis

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

This is an unstable SCFE, defined by the inability to bear weight even with crutches. Unstable slips, especially when treated with forceful or inadvertent closed reduction, carry a high risk of avascular necrosis (AVN), historically up to 47-50%.

Question 2448

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal female with a Risser stage 0 presents with a right thoracic curve of 32 degrees on standing posteroanterior radiograph. She is prescribed a thoracolumbosacral orthosis (TLSO). What is the primary established goal of this treatment?

. To permanently reduce the curve magnitude by at least 50%
. To prevent curve progression to greater than 50 degrees
. To delay the need for surgery until she reaches skeletal maturity
. To improve pulmonary function tests
. To completely resolve the associated rib hump

Correct Answer & Explanation

. To prevent curve progression to greater than 50 degrees

Explanation

The primary goal of bracing in Adolescent Idiopathic Scoliosis (AIS) is to halt curve progression and prevent it from reaching 50 degrees. Curves greater than 50 degrees often continue to progress in adulthood and typically require surgical intervention.

Question 2449

Topic: Pediatric Hip

An 18-month-old female presents with a waddling gait. Radiographs reveal a dislocated left hip with an acetabular index of 40 degrees. During the planned open reduction, which structure is considered the most inferior block to concentric reduction of the femoral head into the true acetabulum?

. Inverted limbus
. Ligamentum teres
. Pulvinar
. Transverse acetabular ligament
. Iliopsoas tendon

Correct Answer & Explanation

. Transverse acetabular ligament

Explanation

Blocks to reduction in DDH include the pulvinar, ligamentum teres, inverted limbus, iliopsoas, and the transverse acetabular ligament. The transverse acetabular ligament spans the inferior acetabular notch and must often be incised or tensioned to allow concentric reduction.

Question 2450

Topic: Pediatric Hip

A 9-year-old boy presents with a unilateral stable slipped capital femoral epiphysis (SCFE). His height is in the 10th percentile and weight in the 90th percentile. Based on his age and body habitus, which of the following screening tests is most appropriate?

. Growth hormone levels
. Thyroid-stimulating hormone (TSH) and free T4
. Serum calcium and phosphate
. Hemoglobin A1c
. Testosterone levels

Correct Answer & Explanation

. Thyroid-stimulating hormone (TSH) and free T4

Explanation

Patients presenting with SCFE under the age of 10 or over the age of 16, or those with atypical body habitus (e.g., short stature), should be evaluated for endocrine disorders. Hypothyroidism is the most common endocrine disorder associated with atypical SCFE.

Question 2451

Topic: Pediatric Upper Extremity & Spine

In the Lenke classification system for Adolescent Idiopathic Scoliosis, a minor thoracic curve is defined as structural if it exhibits a Cobb angle of at least what magnitude on supine side-bending radiographs?

. 10 degrees
. 15 degrees
. 20 degrees
. 25 degrees
. 30 degrees

Correct Answer & Explanation

. 25 degrees

Explanation

In the Lenke classification, a minor curve is considered structural if it fails to correct to less than 25 degrees on supine side-bending radiographs. Alternatively, it is structural if there is kyphosis of at least +20 degrees in that region.

Question 2452

Topic: Pediatric Hip

A 6-month-old male with DDH undergoes a closed reduction and spica casting. A post-reduction MRI is obtained to confirm reduction. To minimize the risk of avascular necrosis (AVN), the hip must NOT be immobilized in which of the following excessive positions?

. Excessive flexion > 120 degrees
. Excessive abduction > 60 degrees
. Excessive adduction > 10 degrees
. Excessive internal rotation > 30 degrees
. Excessive external rotation > 45 degrees

Correct Answer & Explanation

. Excessive abduction > 60 degrees

Explanation

To minimize the risk of AVN, the hip should be immobilized in the 'human position' of roughly 90-100 degrees of flexion and moderate abduction. Excessive abduction (e.g., >60 degrees) significantly increases the tension on the medial circumflex femoral artery, leading to AVN.

Question 2453

Topic: Pediatric Hip

A 14-year-old male presents with global hip stiffness and pain 8 months after undergoing in-situ single-screw fixation for a stable right SCFE. Radiographs show a joint space of 2 mm and profound osteopenia. The screw tip is positioned 3 mm from the subchondral bone. What is the most likely cause of his current symptoms?

. Avascular necrosis
. Implant failure
. Chondrolysis
. Septic arthritis
. Heterotopic ossification

Correct Answer & Explanation

. Chondrolysis

Explanation

The patient has chondrolysis, characterized by diffuse joint space narrowing (<3 mm) and global loss of motion. The most common cause in the setting of SCFE treatment is unrecognized hardware penetration into the joint space.

Question 2454

Topic: Pediatric Hip

During a surgical dislocation and subcapital realignment (modified Dunn procedure) for a severe SCFE, which of the following blood supply sources is most critical to protect while developing the retinacular flap?

. Ascending branch of the lateral femoral circumflex artery
. Deep branch of the medial femoral circumflex artery
. Ligamentum teres artery
. Inferior gluteal artery
. Obturator artery

Correct Answer & Explanation

. Deep branch of the medial femoral circumflex artery

Explanation

The deep branch of the medial femoral circumflex artery (MFCA) provides the primary blood supply to the femoral head. It must be meticulously protected within the retinacular flap during surgical hip dislocation to prevent AVN.

Question 2455

Topic: 4. Pediatrics

A 6-week-old female infant born via breech presentation has a completely normal clinical hip examination with negative Barlow and Ortolani maneuvers. Which of the following is the most appropriate management regarding her hip development?

. Discharge from further hip follow-up
. Schedule an AP pelvis radiograph today
. Schedule an ultrasound of the hips at 6 weeks of age
. Prophylactic placement in a Pavlik harness for 6 weeks
. Schedule an AP pelvis radiograph at 6 months of age

Correct Answer & Explanation

. Schedule an ultrasound of the hips at 6 weeks of age

Explanation

Infants with major risk factors for DDH, such as breech presentation at term, should undergo a screening ultrasound at 6 weeks of age (or an AP radiograph at 4-6 months) even if the physical examination is completely normal.

Question 2456

Topic: 4. Pediatrics

A 5-week-old female infant is currently being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, the parents report that the child has stopped actively kicking her left leg. On examination, the infant lacks active knee extension on the left side, though distal perfusion and sensation appear intact. What is the most appropriate next step in management?

. Adjust the posterior straps to increase hip abduction
. Tighten the anterior straps to increase hip flexion
. Perform a closed reduction and apply a hip spica cast
. Discontinue the harness temporarily or loosen the anterior straps
. Order an urgent MRI of the lumbar spine

Correct Answer & Explanation

. Discontinue the harness temporarily or loosen the anterior straps

Explanation

Decreased active knee extension in a Pavlik harness indicates a femoral nerve palsy, typically caused by hyperflexion of the hip. The appropriate management is to loosen the anterior straps or provide a 'harness holiday' until nerve function recovers.

Question 2457

Topic: Pediatric Hip

A 12-year-old boy presents with a 3-week history of right hip pain and a limp. He is diagnosed with a stable slipped capital femoral epiphysis (SCFE). Medical history is significant for primary hypothyroidism. Regarding surgical intervention, which of the following is the most appropriate management strategy?

. In situ pinning of the right hip only
. In situ pinning of the right hip and prophylactic pinning of the left hip
. Spica cast application for 6 weeks
. Open reduction and internal fixation of the right hip
. Bilateral proximal femoral osteotomies

Correct Answer & Explanation

. In situ pinning of the right hip and prophylactic pinning of the left hip

Explanation

Patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) have a significantly higher risk of bilateral SCFE. Prophylactic pinning of the contralateral asymptomatic hip is strongly indicated in these populations.

Question 2458

Topic: Pediatric Hip

A 24-month-old girl presents with a painless waddling gait. Radiographs reveal a unilaterally dislocated right hip with a false acetabulum and significant dysplasia of the true acetabulum. She has no prior treatment history for this condition. What is the most appropriate definitive management?

. Application of a Pavlik harness
. Closed reduction and spica casting
. Open reduction, capsulorrhaphy, and pelvic/femoral osteotomies
. Observation until skeletal maturity followed by total hip arthroplasty
. Botulinum toxin injections to the adductors and bracing

Correct Answer & Explanation

. Open reduction, capsulorrhaphy, and pelvic/femoral osteotomies

Explanation

In children older than 18 to 24 months presenting with neglected DDH, closed reduction is usually impossible or highly unstable. Open reduction combined with pelvic and/or femoral osteotomies is required to correct the bony dysplasia and maintain reduction.

Question 2459

Topic: Pediatric Hip

A 13-year-old boy presents to the emergency department unable to bear weight on his left leg after a minor fall. Radiographs demonstrate a severe slipped capital femoral epiphysis (SCFE). He is scheduled for urgent in situ percutaneous pinning. Based on the stability of his slip, what is the most significant anticipated complication?

. Chondrolysis
. Avascular necrosis (AVN)
. Femoral nerve palsy
. Developmental dysplasia of the hip
. Infection

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

An unstable SCFE is defined clinically by the inability to bear weight, even with crutches. Unstable slips carry a high risk of avascular necrosis (AVN), which can occur in up to 50% of cases regardless of the treatment method.

Question 2460

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarcheal girl is evaluated for adolescent idiopathic scoliosis (AIS). Upright standing radiographs reveal a right thoracic curve of 32 degrees. Her Risser stage is 0. What is the most appropriate management recommendation?

. Observation with follow-up radiographs in 1 year
. Thoracolumbosacral orthosis (TLSO) bracing
. Posterior spinal fusion with pedicle screws
. Anterior spinal tethering
. Physical therapy focusing on core strengthening only

Correct Answer & Explanation

. Thoracolumbosacral orthosis (TLSO) bracing

Explanation

Bracing is indicated in growing children (Risser 0-2, premenarcheal) with idiopathic scoliosis curves between 25 and 45 degrees. A TLSO brace aims to halt curve progression during the period of rapid adolescent growth.

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