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4. Pediatrics MCQs

Practice Set 132 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 2621

Topic: 4. Pediatrics

A 7-year-old boy sustained a head contusion and small bowel injuries in a motor vehicle accident in which he was wearing a lap belt. He subsequently required a bowel resection. Six weeks after the accident, his parents note a painful mass in his lower back. His neurologic examination is normal. A radiograph and CT scans are shown in Figures 47a through 47c. Definitive management should now consist of

. transcutaneous electrical stimulation and a lumbar corset.
. transforaminal interbody fusion.
. posterior instrumented L2-L3 reduction and fusion.
. anterior interbody fusion with a cage.
. spine extension bracing.

Correct Answer & Explanation

. transcutaneous electrical stimulation and a lumbar corset.

Explanation

The posttraumatic lumbar kyphotic deformity will not remodel and is likely to worsen with time because the central line of gravity lies anterior to the deformity and the ligamentous disruption will not heal. The worsening deformity also puts the patient at some risk for future neurologic damage. Ebraheim NA, Savolain ER, Southworth SR, et al: Pediatric lumbar seat belt injuries. Orthopedics 1991;14:1010-1013.

Question 2622

Topic: Pediatric Hip

A 13-year-old obese male presents with acute left hip pain and an inability to bear weight following a minor fall. He reports intermittent mild hip pain for 3 months prior. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most significant risk factor for developing avascular necrosis (AVN) in this patient?

. Duration of prodromal symptoms
. Inability to bear weight at presentation
. Degree of posterior slip angle
. Use of a single cannulated screw for fixation
. Age of the patient

Correct Answer & Explanation

. Duration of prodromal symptoms

Explanation

The inability to bear weight, with or without crutches, defines an unstable SCFE according to the Loder classification. Unstable slips carry a significantly higher risk of AVN (up to 47%) compared to stable slips.

Question 2623

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy falls from monkey bars and sustains a significantly displaced, extension-type supracondylar humerus fracture. On examination, he is unable to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. Which nerve 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) is the most commonly injured nerve in extension-type supracondylar humerus fractures. Injury presents as an inability to form the "OK" sign due to weakness of the flexor pollicis longus and flexor digitorum profundus to the index finger.

Question 2624

Topic: Pediatric Hip

A 6-week-old female infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 2-week follow-up, the parents report she has stopped actively kicking her left leg. Examination reveals decreased active knee extension on the left side. What is the most appropriate next step in management?

. Immediate surgical exploration
. Adjustment of the anterior straps to increase hip flexion
. Discontinuation of the Pavlik harness for a period of rest
. Application of a rigid abduction orthosis
. Reassurance and continued use of the harness as prescribed

Correct Answer & Explanation

. Immediate surgical exploration

Explanation

The infant has developed a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The harness should be discontinued temporarily until active quadriceps function returns, followed by a reassessment of treatment options.

Question 2625

Topic: Pediatric Hip
A 12-year-old boy presents with right hip pain and inability to bear weight for the past 24 hours. Radiographs confirm a slipped capital femoral epiphysis (SCFE). According to the Loder classification, which of the following is the most likely major complication associated with his condition?
. Chondrolysis
. Avascular necrosis (AVN)
. Legg-Calvé-Perthes disease
. Femoroacetabular impingement
. Premature physeal closure

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

The inability to bear weight with or without crutches defines an unstable SCFE according to the Loder classification. Unstable slips carry a high risk of avascular necrosis (AVN), ranging from 20% to 50%, compared to nearly 0% in stable slips.

Question 2626

Topic: Pediatric Hip

A 3-month-old girl with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, her parents report that she is no longer actively extending her knee on the treated side. Which of the following positioning errors is the most likely cause of this complication?

. Hyperabduction of the hip
. Hyperadduction of the hip
. Hyperflexion of the hip
. Hyperextension of the hip
. Excessive internal rotation

Correct Answer & Explanation

. Hyperabduction of the hip

Explanation

Hyperflexion of the hip in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a femoral nerve palsy and decreased active knee extension. Hyperabduction increases the risk of avascular necrosis (AVN) of the femoral head.

Question 2627

Topic: Pediatric Upper Extremity & Spine

A 14-year-old female presents with a progressive right thoracic scoliotic curve. Radiographs reveal an adolescent idiopathic scoliosis (AIS) curve measuring 55 degrees. Her Risser stage is 0. What is the primary indication for surgical intervention in this patient?

. Presence of an unsegmented congenital bar
. Curve magnitude > 50 degrees with significant remaining growth
. Axial back pain unresponsive to physical therapy
. Preventing progression to a neuromuscular curve
. Associated syrinx on MRI

Correct Answer & Explanation

. Presence of an unsegmented congenital bar

Explanation

In Adolescent Idiopathic Scoliosis, surgical fusion is generally indicated for curves greater than 45-50 degrees, especially in patients with significant remaining growth (Risser 0). This prevents further progression, which inevitably occurs even after skeletal maturity for curves >50 degrees.

Question 2628

Topic: Pediatric Hip
A 9-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Anteroposterior pelvis radiographs reveal that the lateral pillar of the femoral head has collapsed to less than 50% of its original height. According to the Herring Lateral Pillar Classification, into which group does he fall, and what is the general prognosis?
. Group A; Excellent prognosis with non-operative care
. Group B; Good prognosis with surgical containment
. Group C; Poor prognosis regardless of treatment
. Group B/C border; Excellent prognosis with physical therapy
. Group C; Good prognosis with immediate femoral osteotomy

Correct Answer & Explanation

. Group C; Poor prognosis regardless of treatment

Explanation

Maintaining <50% of the lateral pillar height defines Herring Group C. Children over the age of 8 with Group C involvement have a generally poor prognosis regarding joint congruency and early osteoarthritis, regardless of whether surgical containment is performed.

Question 2629

Topic: Pediatric Upper Extremity & Spine
A 5-year-old girl sustains a Gartland type III supracondylar humerus fracture. Upon evaluation in the emergency department, her hand is pink and warm, but the radial pulse is absent. What is the most appropriate next step in management?
. Immediate exploration of the brachial artery
. Closed reduction and percutaneous pinning, then re-evaluate the pulse
. CT angiogram of the upper extremity
. Application of a hyperflexion long arm cast
. Open reduction and internal fixation with prophylactic fasciotomies

Correct Answer & Explanation

. Closed reduction and percutaneous pinning, then re-evaluate the pulse

Explanation

A "pulseless, pink" hand following a supracondylar humerus fracture indicates adequate collateral perfusion. The standard of care is urgent closed reduction and percutaneous pinning (CRPP), which frequently restores the anatomic alignment and the radial pulse.

Question 2630

Topic: 4. Pediatrics

A 5-year-old girl presents with a painless waddling gait. Radiographs reveal developmental coxa vara. The Hilgenreiner Epiphyseal Angle (HEA) is measured at 65 degrees. What is the most appropriate management?

. Observation with annual radiographs
. Abduction bracing for 6 months
. Proximal femoral varus osteotomy
. Proximal femoral valgus osteotomy
. In situ pinning of the capital femoral epiphysis

Correct Answer & Explanation

. Observation with annual radiographs

Explanation

An HEA greater than 60 degrees in congenital coxa vara indicates a high risk of progression and nonunion of the cartilaginous defect. The definitive treatment is a valgus-producing proximal femoral osteotomy to convert shear forces into compressive forces.

Question 2631

Topic: 4. Pediatrics

A 4-month-old infant presents to the emergency department with a swollen left thigh. Radiographs reveal a metaphyseal "corner" fracture of the distal femur. Which of the following steps is the most critical next action?

. Genetic testing for Osteogenesis Imperfecta (COL1A1/COL1A2)
. Immediate closed reduction and spica casting under anesthesia
. Perform a complete skeletal survey and notify Child Protective Services
. Prescribe bisphosphonates for suspected metabolic bone disease
. Obtain a stat MRI of the femur to rule out osteomyelitis

Correct Answer & Explanation

. Genetic testing for Osteogenesis Imperfecta (COL1A1/COL1A2)

Explanation

Metaphyseal corner (or bucket-handle) fractures in non-ambulatory infants are highly specific for non-accidental trauma (child abuse). The immediate, mandatory next steps include ensuring the child's safety, performing a skeletal survey, and notifying CPS.

Question 2632

Topic: Pediatric Hip

A 9-year-old girl, whose weight is in the 40th percentile, presents with right groin pain and a limp. Radiographs confirm a slipped capital femoral epiphysis (SCFE).

Given her presentation, an endocrine workup is indicated. Which of the following is the most common underlying endocrine disorder associated with this condition?

. Hypothyroidism
. Growth hormone deficiency
. Hyperparathyroidism
. Hypogonadism
. Panhypopituitarism

Correct Answer & Explanation

. Hypothyroidism

Explanation

Atypical SCFE (patients aged <10 or >16, or weight < 50th percentile) warrants an endocrine workup. Hypothyroidism is the most common underlying endocrine disorder associated with atypical SCFE.

Question 2633

Topic: Pediatric Upper Extremity & Spine
A 5-year-old boy sustains a type III extension supracondylar humerus fracture. After closed reduction and percutaneous pinning, the hand is noted to be pink but lacks a palpable radial pulse. Doppler confirms a monophasic signal at the wrist. What is the most appropriate next step in management?
. Immediate exploration of the brachial artery
. Removal of all pins and open reduction
. Observation and elevation
. Stellate ganglion block
. Arteriography

Correct Answer & Explanation

. Observation and elevation

Explanation

A pink, pulseless hand following adequate closed reduction and pinning of a supracondylar humerus fracture indicates sufficient collateral circulation. Observation is the recommended management, as pulses typically return over several days.

Question 2634

Topic: Pediatric Hip

A 3-month-old girl with developmental dysplasia of the hip (DDH) is being treated in a Pavlik harness. During a follow-up examination, the orthopedist notes decreased active extension of the left knee. What is the most likely cause of this finding?

. Sciatic nerve palsy
. Femoral nerve palsy
. Obturator nerve palsy
. Avascular necrosis of the femoral head
. Septic arthritis

Correct Answer & Explanation

. Sciatic nerve palsy

Explanation

Hyperflexion of the hip in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a transient femoral nerve palsy. This presents as decreased active knee extension and usually resolves with temporary relaxation of the anterior straps.

Question 2635

Topic: 4. Pediatrics
A 14-year-old boy sustains a juvenile Tillaux fracture of the distal tibia while skateboarding. This fracture pattern occurs due to the specific sequence of distal tibial physeal closure. What mechanism of injury is most classically responsible for this fracture?
. External rotation
. Internal rotation
. Hyperplantarflexion
. Direct medial trauma
. Axial loading

Correct Answer & Explanation

. External rotation

Explanation

A juvenile Tillaux fracture is a Salter-Harris III avulsion of the anterolateral distal tibial epiphysis caused by an external rotation force on the foot. It occurs because the lateral portion of the distal tibial physis is the last to close.

Question 2636

Topic: 4. Pediatrics

A 6-year-old child falls from monkey bars and sustains a displaced extension-type supracondylar humerus fracture. Which of the following physical examination findings corresponds to the most common neurological injury associated with this specific fracture pattern?

. Inability to abduct the fingers against resistance
. Inability to flex the interphalangeal joint of the thumb
. Loss of sensation over the dorsal first web space
. Inability to extend the wrist
. Clawing of the ring and small fingers

Correct Answer & Explanation

. Inability to abduct the fingers against resistance

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. Injury results in the inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger (an abnormal "A-OK" sign).

Question 2637

Topic: Pediatric Hip

A 13-year-old boy underwent in situ pinning for a stable slipped capital femoral epiphysis (SCFE) 6 months ago. He now presents with a severely stiff, painful hip. Radiographs show a concentric, severe narrowing of the joint space. What is the most likely diagnosis?

. Avascular necrosis (AVN)
. Chondrolysis
. Septic arthritis
. Implant failure
. Femoroacetabular impingement

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

Chondrolysis is a devastating complication of SCFE characterized by acute loss of articular cartilage and a globally stiff, painful hip. It is strongly associated with unrecognized intra-articular hardware penetration.

Question 2638

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal girl presents with adolescent idiopathic scoliosis. Radiographs demonstrate a right thoracic curve of 32 degrees. Her Risser stage is 0. What is the most appropriate management?

. Observation with repeat radiographs in 6 months
. TLSO bracing
. Posterior spinal fusion
. Anterior vertebral body tethering
. Physical therapy (Schroth method) alone

Correct Answer & Explanation

. Observation with repeat radiographs in 6 months

Explanation

Bracing in adolescent idiopathic scoliosis is indicated for curves between 25 and 40 degrees in skeletally immature patients (Risser 0-2). The goal of the TLSO brace is to halt progression, not to correct the existing deformity.

Question 2639

Topic: Pediatric Hip

A 13-year-old obese boy presents with 3 weeks of left knee pain and a limp. Examination reveals obligatory external rotation of the left hip when it is passively flexed. Radiographs confirm a mild slipped capital femoral epiphysis (SCFE). Which of the following is the most appropriate initial management?

. Closed reduction and spica casting
. In situ pinning with a single cannulated screw
. In situ pinning with three cannulated screws
. Open reduction and internal fixation
. Proximal femoral osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

The standard of care for a stable, mild SCFE is in situ pinning with a single central cannulated screw. Multiple screws increase the risk of joint penetration and avascular necrosis without providing significant biomechanical advantage.

Question 2640

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a completely displaced extension-type supracondylar humerus fracture. On initial presentation, his hand is pink but the radial pulse is absent. Following closed reduction and percutaneous pinning, the hand remains pink and well-perfused, but the radial pulse is still non-palpable. What is the most appropriate next step in management?

. Immediate vascular exploration
. Perform a sympathetic block
. Close observation with pulse oximetry
. Remove the pins and open the fracture
. Angiography of the upper extremity

Correct Answer & Explanation

. Immediate vascular exploration

Explanation

A pink, pulseless hand following adequate reduction of a supracondylar humerus fracture should be managed with close clinical observation. Vascular exploration is indicated only if the hand is persistently cold, pale, and poorly perfused after reduction.

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