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4. Pediatrics MCQs

Practice Set 29 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 561

Topic: Pediatric Hip

A 5-year-old boy presents with a limp and hip pain. Radiographs demonstrate sclerosis and fragmentation of the proximal femoral epiphysis. Which radiographic sign is considered a 'head-at-risk' sign in Legg-Calve-Perthes disease?

. Crescent sign
. Gage sign
. Klein's line disruption
. Waldenstrom sign
. Trethowan sign

Correct Answer & Explanation

. Gage sign

Explanation

The Gage sign (a V-shaped radiolucency in the lateral portion of the epiphysis and adjacent metaphysis) is a classic 'head-at-risk' sign indicating potential for poor outcomes in Perthes disease.

Question 562

Topic: 4. Pediatrics

A 9-year-old boy with a midshaft femur fracture is treated with flexible intramedullary nails. He presents 6 months later with a 1.5 cm leg length discrepancy (treated leg is longer). What is the primary mechanism for this finding?

. Hardware migration stimulating the physis
. Fracture hyperaemia causing physeal overgrowth
. Failure to anatomically reduce the fracture initially
. Premature closure of the contralateral physis
. Loss of fixation leading to distraction

Correct Answer & Explanation

. Fracture hyperaemia causing physeal overgrowth

Explanation

Pediatric femur fractures often undergo a period of overgrowth (typically 1-2 cm) due to fracture hyperemia stimulating the proximal and distal physes. This effect is most prominent in children aged 2 to 10 years.

Question 563

Topic: 4. Pediatrics

A child with cerebral palsy (GMFCS Level IV) is noted to have lateral subluxation of the hip on AP pelvic radiographs. The Reimers migration index is measured at 45%. What is the most appropriate management?

. Observation with repeat radiographs in 1 year
. Botulinum toxin injections to the adductors
. Soft tissue release alone (adductor tenotomy)
. Varus derotational osteotomy (VDRO) with or without pelvic osteotomy
. Total hip arthroplasty

Correct Answer & Explanation

. Varus derotational osteotomy (VDRO) with or without pelvic osteotomy

Explanation

In cerebral palsy patients, a Reimers migration index >40% typically requires bony reconstructive surgery (VDRO and pelvic osteotomy) because soft tissue releases alone are insufficient to reliably stabilize the hip.

Question 564

Topic: 4. Pediatrics

A neonate is found to have bilateral posteromedial bowing of the tibia. Which of the following conditions is most commonly associated with this specific type of tibial bowing?

. Neurofibromatosis type 1
. Osteogenesis imperfecta
. Calcaneovalgus foot deformity
. Congenital pseudoarthrosis of the tibia
. Fibular hemimelia

Correct Answer & Explanation

. Calcaneovalgus foot deformity

Explanation

Posteromedial bowing of the tibia in a newborn is typically benign and is strongly associated with a calcaneovalgus foot deformity. Unlike anterolateral bowing, it does not lead to pseudoarthrosis and often resolves spontaneously.

Question 565

Topic: Pediatric Hip

A 13-year-old obese male presents with acute worsening of chronic left hip pain. On examination, he has an obligatory external rotation of the hip during passive flexion. Radiographs demonstrate a severe, unstable slipped capital femoral epiphysis (SCFE). What is the most severe and frequent complication specifically associated with an unstable SCFE?

. Chondrolysis
. Avascular necrosis of the femoral head
. Femoroacetabular impingement
. Leg length discrepancy
. Slipped progression

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Unstable SCFE carries a significantly higher risk of avascular necrosis (AVN) of the femoral head, with rates up to 50%. Chondrolysis is more commonly associated with prominent hardware following in situ pinning.

Question 566

Topic: Pediatric Hip

A 3-month-old female is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. Her parents report that she is no longer actively extending her knee on the treated side. Which of the following nerve palsies is most likely occurring?

. Sciatic nerve palsy
. Obturator nerve palsy
. Femoral nerve palsy
. Common peroneal nerve palsy
. Superior gluteal nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, typically occurring when the hip is in hyperflexion. The harness should be adjusted or discontinued until active quadriceps function returns.

Question 567

Topic: Pediatric Hip

In a 6-year-old boy diagnosed with Legg-Calve-Perthes disease, the Herring lateral pillar classification is used to determine prognosis. A Type B classification indicates that what percentage of the lateral pillar height is maintained on the anteroposterior radiograph?

. Less than 25%
. Between 25% and 50%
. Greater than 50%
. Exactly 100%
. 0%

Correct Answer & Explanation

. Greater than 50%

Explanation

According to the Herring classification, Type B is defined by the maintenance of >50% of the lateral pillar height. Type C indicates <50% height maintenance, portending a worse prognosis.

Question 568

Topic: Pediatric Upper Extremity & Spine

A 5-year-old girl falls from monkey bars and sustains an extension-type supracondylar humerus fracture. On examination, which finding is most indicative of the most commonly injured nerve in this specific fracture pattern?

. Inability to extend the wrist
. Inability to flex the distal interphalangeal joint of the index finger
. Numbness over the dorsal first web space
. Inability to cross the index and middle fingers
. Weakness of shoulder abduction

Correct Answer & Explanation

. Inability to flex the distal interphalangeal joint of the index finger

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. Injury is assessed by the inability to flex the IP joint of the thumb and the DIP joint of the index finger (the 'OK' sign).

Question 569

Topic: Pediatric Lower Extremity

An infant with idiopathic clubfoot is undergoing serial casting using the Ponseti method. According to the principles of this method, which component of the deformity is corrected first?

. Equinus
. Varus
. Adductus
. Cavus
. Internal rotation

Correct Answer & Explanation

. Cavus

Explanation

The Cavus deformity is corrected first in the Ponseti method by elevating the first ray to supinate the forefoot and align it with the hindfoot. Equinus is the final deformity corrected, often requiring a percutaneous Achilles tenotomy.

Question 570

Topic: 4. Pediatrics
A 4-year-old child presents with a history of multiple low-energy fractures and bluish discoloration of the sclerae. Genetic testing would most likely reveal a defect involving the production of which of the following?
. Type I collagen
. Type II collagen
. Type III collagen
. Type IV collagen
. Fibroblast growth factor receptor 3 (FGFR3)

Correct Answer & Explanation

. Type I collagen

Explanation

The clinical presentation is classic for Osteogenesis Imperfecta (OI). OI is primarily caused by mutations in the COL1A1 or COL1A2 genes, which lead to quantitative or qualitative defects in Type I collagen.

Question 571

Topic: 4. Pediatrics

A 12-year-old boy sustains a Salter-Harris Type IV fracture of the medial malleolus. The primary orthopaedic rationale for precise, anatomic open reduction and internal fixation of this injury is to prevent which of the following?

. Nonunion
. Avascular necrosis of the talus
. Premature physeal closure and bar formation
. Post-traumatic osteoarthritis of the syndesmosis
. Chronic regional pain syndrome

Correct Answer & Explanation

. Premature physeal closure and bar formation

Explanation

Salter-Harris IV fractures cross the epiphysis, physis, and metaphysis. Anatomic reduction is mandatory to align the physeal zones and prevent the formation of a bony bar, which leads to growth arrest and angular deformity.

Question 572

Topic: 4. Pediatrics

A 3-year-old boy is diagnosed with infantile Blount disease. Radiographs show a Langenskiold stage II lesion of the medial proximal tibia. What is the most appropriate initial management?

. Observation alone
. Proximal tibial valgus-producing osteotomy
. Hemiepiphysiodesis of the lateral proximal tibia
. Knee-ankle-foot orthosis (KAFO)
. Guided growth with tension-band plates

Correct Answer & Explanation

. Knee-ankle-foot orthosis (KAFO)

Explanation

For children under 4 years of age with Langenskiold stage I or II infantile Blount disease, a bracing regimen with a KAFO is the initial treatment of choice. Surgery is indicated if bracing fails or if the child is older or has advanced staging.

Question 573

Topic: 4. Pediatrics

A newborn is noted to have a prominent anterolateral bow of the distal tibia. Radiographs show medullary sclerosis and cortical thickening. This condition has the strongest association with which of the following systemic disorders?

. Osteogenesis imperfecta
. Neurofibromatosis type 1
. Achondroplasia
. Marfan syndrome
. Cleidocranial dysplasia

Correct Answer & Explanation

. Neurofibromatosis type 1

Explanation

Congenital anterolateral bowing of the tibia is a precursor to congenital pseudarthrosis of the tibia. It has a strong clinical association with Neurofibromatosis type 1 (NF1).

Question 574

Topic: 4. Pediatrics

A 10-year-old boy jumps to catch a basketball and feels a 'pop' in his right knee. On examination, he has a palpable defect inferior to the patella and an extensor lag of 30 degrees. Lateral radiograph reveals a high-riding patella with a small bony fragment inferior to it. What is the most likely diagnosis?

. Tibial tubercle avulsion fracture
. Mid-substance patellar tendon rupture
. Patellar sleeve fracture
. Bipartite patella
. Sinding-Larsen-Johansson syndrome

Correct Answer & Explanation

. Patellar sleeve fracture

Explanation

A patellar sleeve fracture is a pediatric injury involving avulsion of the unossified distal patellar cartilage along with a small shell of bone. It presents with an extensor lag, patella alta, and a characteristic small inferior pole bony fragment on X-ray.

Question 575

Topic: Pediatric Hip

A 13-year-old obese male undergoes in situ pinning for a stable slipped capital femoral epiphysis (SCFE). Six months postoperatively, he presents with severe hip stiffness, pain, and a 50% reduction in joint space on radiographs. No signs of infection are present. What is the most likely diagnosis?

. Avascular necrosis
. Chondrolysis
. Implant failure
. Femoroacetabular impingement
. Septic arthritis

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a known complication of SCFE, characterized by acute cartilage destruction, joint space narrowing to less than 3 mm, and severe stiffness. It can occur secondary to unrecognized pin penetration into the joint or intrinsically from the disease process.

Question 576

Topic: Pediatric Hip
In evaluating a 9-year-old boy with Legg-Calvรฉ-Perthes disease, which of the following is the most significant prognostic factor for long-term hip deformity?
. Degree of medial subluxation
. Age at the onset of symptoms
. Presence of a Gage sign
. Metaphyseal cysts
. Extent of anterior epiphyseal involvement

Correct Answer & Explanation

. Age at the onset of symptoms

Explanation

The two most critical prognostic factors in Legg-Calvรฉ-Perthes disease are the age of onset (worse prognosis if older than 8 years) and the lateral pillar classification (extent of lateral epiphyseal involvement). Older children have less time for spherical remodeling before skeletal maturity.

Question 577

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy presents with a completely displaced posterolateral supracondylar humerus fracture. Which of the following neurologic deficits is most likely to be observed?

. Inability to extend the wrist
. Inability to cross the fingers
. Inability to flex the interphalangeal joint of the thumb
. Loss of sensation over the dorsal first web space
. Loss of sensation over the small finger

Correct Answer & Explanation

. Inability to flex the interphalangeal joint of the thumb

Explanation

Posterolateral displacement of a supracondylar humerus fracture stretches anterior structures, predominantly putting the anterior interosseous nerve (AIN) at risk. AIN palsy presents with weakness in the flexor pollicis longus and flexor digitorum profundus to the index finger, resulting in an inability to make the 'A-OK' sign.

Question 578

Topic: 4. Pediatrics

When treating idiopathic congenital talipes equinovarus using the Ponseti method, what is the correct sequence of deformity correction?

. Cavus, Adductus, Varus, Equinus
. Adductus, Varus, Cavus, Equinus
. Equinus, Cavus, Varus, Adductus
. Varus, Cavus, Adductus, Equinus
. Cavus, Varus, Adductus, Equinus

Correct Answer & Explanation

. Cavus, Varus, Adductus, Equinus

Explanation

The Ponseti method corrects the deformities of clubfoot in a specific sequence summarized by the acronym CAVE: Cavus (by elevating the first ray), Adductus, Varus, and finally Equinus. The equinus is corrected last, often requiring a percutaneous Achilles tenotomy.

Question 579

Topic: Pediatric Hip

A 24-month-old girl is newly diagnosed with developmental dysplasia of the hip (DDH) demonstrating a completely dislocated right hip. What is the most appropriate initial management?

. Pavlik harness application
. Closed reduction and spica casting
. Open reduction and spica casting
. Open reduction, pelvic osteotomy, and femoral shortening
. Observation until age 4 followed by salvage osteotomy

Correct Answer & Explanation

. Open reduction, pelvic osteotomy, and femoral shortening

Explanation

In children older than 18 to 24 months with a completely dislocated hip, open reduction is generally required as closed reduction is rarely successful. Concomitant pelvic and femoral shortening osteotomies are frequently necessary to safely reduce the hip without excessive tension that risks avascular necrosis.

Question 580

Topic: 4. Pediatrics

A 7-year-old child with spastic diplegic cerebral palsy presents for routine follow-up. Pelvic radiographs reveal a Reimers migration percentage of 45% in the left hip. What is the most appropriate management?

. Botulinum toxin injections to the adductors
. Adductor tenotomy and obturator neurectomy
. Observation with repeat radiographs in 1 year
. Varus derotational osteotomy (VDRO) of the femur and pelvic osteotomy
. Total hip arthroplasty

Correct Answer & Explanation

. Varus derotational osteotomy (VDRO) of the femur and pelvic osteotomy

Explanation

A Reimers migration percentage greater than 40% in a child with cerebral palsy indicates significant hip subluxation that is unlikely to respond to soft-tissue releases alone. Bony reconstruction with a varus derotational femoral osteotomy (VDRO), often combined with a pelvic osteotomy, is the standard of care to stabilize the hip.

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