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4. Pediatrics MCQs

Practice Set 313 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 6241

Topic: 4. Pediatrics
A 14-year-old boy sustains an ankle injury while playing soccer. Radiographs reveal a Salter-Harris III fracture of the anterolateral distal tibia. Which of the following ligaments is responsible for the avulsion of this fracture fragment?
. Anterior talofibular ligament (ATFL)
. Calcaneofibular ligament (CFL)
. Anterior inferior tibiofibular ligament (AITFL)
. Posterior inferior tibiofibular ligament (PITFL)
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament (AITFL)

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. It occurs in adolescents because the distal tibial physis closes in a specific pattern: central, then anteromedial, then posteromedial, and finally anterolateral. An external rotation force of the foot within the mortise causes the anterior inferior tibiofibular ligament (AITFL) to avulse the anterolateral epiphysis, which is the last portion of the physis to close.

Question 6242

Topic: 4. Pediatrics
A 3-year-old girl presents with progressive bowing of her left leg. Radiographs demonstrate a sharp varus angulation at the proximal tibial metaphysis with beaking and fragmentation of the medial aspect of the epiphysis. She is diagnosed with infantile Blount disease. According to the Langenskiöld classification, at what stage is a proximal tibial osteotomy generally recommended to prevent permanent physeal damage?
. Stage I
. Stage II
. Stage III
. Stage V
. Stage VI

Correct Answer & Explanation

. Stage III

Explanation

Infantile Blount disease is characterized by disordered endochondral ossification of the medial aspect of the proximal tibial physis. The Langenskiöld classification describes the radiographic progression from Stage I to VI. Bracing (KAFO) is typically attempted for Stages I and II in children under 3 years of age. However, by Stage III (characterized by a step-off in the metaphysis), or if the child is older than 3-4 years, surgical intervention with a proximal tibial valgus osteotomy is recommended. Surgery at this stage restores normal mechanical alignment and prevents irreversible physeal damage, which typically occurs in Stages V and VI with the formation of a physeal bar.

Question 6243

Topic: Pediatric Hip

A 9-year-old boy with a BMI in the 99th percentile presents with a stable slipped capital femoral epiphysis (SCFE) of the left hip. He has a known medical history of hypothyroidism. What is the most appropriate management for the contralateral right hip?

. Observation with serial radiographs every 6 months
. Spica casting in internal rotation
. Prophylactic in situ pinning
. Closed reduction and percutaneous pinning
. Open reduction and internal fixation

Correct Answer & Explanation

. Prophylactic in situ pinning

Explanation

Correct Answer: Prophylactic in situ pinningProphylactic pinning of the contralateral hip is highly recommended in patients with SCFE who have underlying endocrine disorders (such as hypothyroidism or panhypopituitarism), renal osteodystrophy, previous radiation therapy, or are under 10 years of age. These patients have a significantly higher risk of developing bilateral involvement compared to idiopathic cases.

Question 6244

Topic: Pediatric Hip

During an open reduction of a developmental dysplasia of the hip (DDH) via a medial approach, the surgeon encounters resistance to concentric reduction. Which of the following structures is considered an intra-articular block to reduction?

. Iliopsoas tendon
. Adductor longus
. Transverse acetabular ligament
. Rectus femoris
. Tensor fasciae latae

Correct Answer & Explanation

. Transverse acetabular ligament

Explanation

Correct Answer: Transverse acetabular ligamentBlocks to reduction in DDH are categorized as extra-articular or intra-articular. Extra-articular blocks include the iliopsoas tendon and adductor longus. Intra-articular blocks include the inverted limbus, hypertrophied pulvinar, ligamentum teres, and a contracted transverse acetabular ligament. The transverse acetabular ligament must often be incised to allow the femoral head to seat deeply within the true acetabulum.

Question 6245

Topic: Pediatric Lower Extremity

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

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

Correct Answer: Cavus, Adductus, Varus, EquinusThe Ponseti method corrects clubfoot deformities in a specific, sequential order remembered by the acronym CAVE: Cavus (corrected first by elevating the first ray to align the forefoot with the hindfoot), Adductus, Varus, and finally Equinus. Equinus is corrected last, often requiring a percutaneous Achilles tenotomy once the other deformities are fully resolved.

Question 6246

Topic: Pediatric Hip
In the evaluation of a 7-year-old boy with Legg-Calvé-Perthes disease, which of the following radiographic classifications is considered the most reliable prognostic indicator for long-term hip outcome?
. Catterall classification
. Salter-Thompson classification
. Herring lateral pillar classification
. Stulberg classification
. Waldenström stages

Correct Answer & Explanation

. Herring lateral pillar classification

Explanation

The Herring lateral pillar classification, assessed during the fragmentation phase of the disease, is the most reliable prognostic indicator for Legg-Calvé-Perthes disease. It evaluates the height of the lateral pillar of the capital femoral epiphysis. Group A has no lateral pillar involvement, Group B has >50% lateral pillar height maintained, and Group C has <50% lateral pillar height maintained. Group C has the poorest prognosis.

Question 6247

Topic: 4. Pediatrics

The pathogenesis of infantile Blount disease (tibia vara) is best explained by which of the following biomechanical principles?

. Wolff's law
. Hueter-Volkmann principle
. Delpech principle
. Pauwels' principle
. Hooke's law

Correct Answer & Explanation

. Hueter-Volkmann principle

Explanation

Correct Answer: Hueter-Volkmann principleThe Hueter-Volkmann principle states that increased compressive forces on a physis inhibit growth, while decreased forces stimulate growth. In infantile Blount disease, excessive compressive forces on the medial proximal tibial physis (often due to early walking and obesity) lead to growth suppression medially, resulting in a progressive varus deformity.

Question 6248

Topic: 4. Pediatrics

A 5-year-old child with spastic quadriplegic cerebral palsy (GMFCS Level V) is undergoing routine hip surveillance. Which of the following radiographic measurements is most critical for determining the need for surgical intervention to prevent hip dislocation?

. Acetabular index
. Center-edge angle of Wiberg
. Reimers migration percentage
. Neck-shaft angle
. Alpha angle

Correct Answer & Explanation

. Reimers migration percentage

Explanation

Correct Answer: Reimers migration percentageReimers migration percentage (or index) is the standard measurement used in cerebral palsy hip surveillance to quantify the lateral displacement of the femoral head out of the acetabulum. A migration percentage >30% indicates subluxation and warrants closer monitoring or soft tissue intervention, while a percentage >50% typically requires bony reconstructive surgery (VDRO and pelvic osteotomy) to prevent painful dislocation.

Question 6249

Topic: 4. Pediatrics

A 3-year-old girl presents with multiple fractures following minimal trauma, blue sclerae, and dentinogenesis imperfecta. Genetic testing is most likely to reveal a mutation affecting the synthesis of which of the following proteins?

. Type I collagen
. Type II collagen
. Type X collagen
. Fibroblast growth factor receptor 3 (FGFR3)
. Cartilage oligomeric matrix protein (COMP)

Correct Answer & Explanation

. Type I collagen

Explanation

Correct Answer: Type I collagenOsteogenesis imperfecta is primarily caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, which encode the alpha-1 and alpha-2 chains of Type I collagen. This structural defect leads to brittle bones, blue sclerae, hearing loss, and dentinogenesis imperfecta. Type II collagen defects cause spondyloepiphyseal dysplasia, FGFR3 mutations cause achondroplasia, and COMP mutations cause pseudoachondroplasia.

Question 6250

Topic: Pediatric Hip

A 13-year-old obese male undergoes in situ pinning for a stable slipped capital femoral epiphysis (SCFE). Postoperatively, he develops severe hip stiffness and pain. Radiographs show concentric joint space narrowing. What is the most likely cause of this complication?

. Avascular necrosis
. Unrecognized hardware penetration into the joint
. Septic arthritis
. Femoroacetabular impingement
. Slipped contralateral hip

Correct Answer & Explanation

. Unrecognized hardware penetration into the joint

Explanation

Correct Answer: Unrecognized hardware penetration into the jointChondrolysis is characterized by concentric joint space narrowing and severe stiffness following treatment for SCFE. The most common iatrogenic cause is unrecognized pin penetration into the joint space. Avascular necrosis typically presents with segmental collapse rather than concentric joint space narrowing.

Question 6251

Topic: Pediatric Hip

A 6-week-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, the parents report that the infant has stopped kicking her leg on the affected side. On examination, there is absent active knee extension. Which of the following adjustments to the harness is most appropriate?

. Increase the flexion of the anterior straps
. Decrease the flexion of the anterior straps
. Increase the abduction of the posterior straps
. Decrease the abduction of the posterior straps
. Discontinue the harness immediately and schedule closed reduction

Correct Answer & Explanation

. Decrease the flexion of the anterior straps

Explanation

Correct Answer: Decrease the flexion of the anterior strapsHyperflexion in a Pavlik harness can lead to a compressive femoral nerve palsy, presenting as decreased active knee extension and a lack of kicking. The appropriate management is to decrease the flexion of the anterior straps or temporarily discontinue the harness until nerve function recovers.

Question 6252

Topic: Pediatric Lower Extremity

A 3-year-old boy who was successfully treated for idiopathic clubfoot with the Ponseti method and an Achilles tenotomy presents with a recurrent equinovarus deformity. What is the most common cause of relapse in this patient population?

. Failure to perform an anterior tibial tendon transfer
. Noncompliance with bracing
. Under-correction during the initial casting phase
. Premature Achilles tenotomy
. Neuromuscular etiology

Correct Answer & Explanation

. Noncompliance with bracing

Explanation

Correct Answer: Noncompliance with bracingThe most common cause of clubfoot relapse after successful Ponseti casting and tenotomy is noncompliance with the foot abduction orthosis (bracing). Strict adherence to the bracing protocol (full-time for 3 months, then nights/naps until age 4) is critical to maintaining the correction.

Question 6253

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Which of the following factors is considered the most significant predictor of the final radiographic and clinical outcome?
. Gender of the patient
. Age at the time of clinical onset
. Body mass index (BMI)
. Presence of a limp at presentation
. Family history of the disease

Correct Answer & Explanation

. Age at the time of clinical onset

Explanation

Age at the onset of symptoms is the most critical prognostic factor in Legg-Calvé-Perthes disease. Children who develop the disease at a younger age (typically under 6-8 years) have a better prognosis due to greater potential for remodeling of the femoral head before skeletal maturity.

Question 6254

Topic: 4. Pediatrics

The pathogenesis of infantile Blount disease is best explained by which of the following biomechanical principles?

. Wolff's Law
. Hueter-Volkmann principle
. Pauwels' principle
. Tension band principle
. Hooke's Law

Correct Answer & Explanation

. Hueter-Volkmann principle

Explanation

Correct Answer: Hueter-Volkmann principleThe Hueter-Volkmann principle states that increased compressive forces on a physis inhibit growth, while decreased forces stimulate growth. In Blount disease, excessive compressive forces on the medial aspect of the proximal tibial physis (often due to early walking and obesity) lead to growth suppression and progressive varus deformity.

Question 6255

Topic: 4. Pediatrics

A 6-year-old child with spastic quadriplegic cerebral palsy (GMFCS Level V) is undergoing routine hip surveillance. Radiographs reveal a Reimers migration percentage of 45% bilaterally. What is the most appropriate management?

. Observation with repeat radiographs in 1 year
. Botulinum toxin injections to the adductors
. Bilateral adductor tenotomies alone
. Bilateral varus derotational osteotomies (VDRO) and pelvic osteotomies
. Bilateral total hip arthroplasties

Correct Answer & Explanation

. Bilateral varus derotational osteotomies (VDRO) and pelvic osteotomies

Explanation

Correct Answer: Bilateral varus derotational osteotomies (VDRO) and pelvic osteotomiesIn children with CP, a Reimers migration percentage >40% indicates significant hip subluxation that is unlikely to respond to soft tissue releases alone. Bony reconstruction, typically involving a proximal femoral varus derotational osteotomy (VDRO) and often a pelvic osteotomy (e.g., Dega or San Diego), is indicated to stabilize the hip and prevent painful dislocation.

Question 6256

Topic: 4. Pediatrics

A 4-year-old girl with a history of multiple low-energy fractures, blue sclerae, and dentinogenesis imperfecta is diagnosed with osteogenesis imperfecta (OI). The most common genetic mutations associated with this condition affect the synthesis of which of the following proteins?

. Type II collagen
. Type I collagen
. Fibrillin-1
. Fibroblast growth factor receptor 3 (FGFR3)
. Cartilage oligomeric matrix protein (COMP)

Correct Answer & Explanation

. Type I collagen

Explanation

Correct Answer: Type I collagenOsteogenesis imperfecta is primarily caused by mutations in the COL1A1 or COL1A2 genes, which encode the alpha-1 and alpha-2 chains of Type I collagen. This leads to quantitative or qualitative defects in Type I collagen, the major structural protein in bone.

Question 6257

Topic: 4. Pediatrics

A 4-year-old boy presents with a displaced lateral condyle fracture of the humerus. Radiographs show a Milch Type II fracture with 3 mm of displacement. Which of the following is the most appropriate definitive management?

. Long arm cast immobilization in full extension
. Long arm cast immobilization in 90 degrees of flexion
. Open reduction and internal fixation (ORIF) with Kirschner wires
. Closed reduction and percutaneous pinning without an arthrogram
. Collar and cuff immobilization

Correct Answer & Explanation

. Open reduction and internal fixation (ORIF) with Kirschner wires

Explanation

Lateral condyle fractures with >2 mm of displacement are generally treated with ORIF to ensure anatomic reduction of the articular surface and physis. Closed reduction and pinning may be attempted, but typically requires an arthrogram to confirm perfect articular alignment.

Question 6258

Topic: Pediatric Hip

A 24-month-old girl recently emigrated from a developing country and is evaluated for a painless limp. Examination reveals a positive Galeazzi sign and asymmetric thigh folds. Radiographs confirm an untreated unilateral developmental dysplasia of the hip (DDH) with a dislocated left hip. What is the most appropriate initial management?

. Pavlik harness trial
. Closed reduction and spica casting
. Open reduction and spica casting
. Observation until skeletal maturity
. Total hip arthroplasty

Correct Answer & Explanation

. Open reduction and spica casting

Explanation

For children over 18-24 months of age with a completely dislocated hip, open reduction is generally the initial treatment of choice. Closed reduction and Pavlik harness have unacceptably high failure and AVN rates in this older age group.

Question 6259

Topic: Pediatric Lower Extremity

An infant with a severe idiopathic clubfoot is undergoing serial manipulation and casting using the Ponseti method. According to the principles of this method, which of the following deformity components is corrected last?

. Cavus
. Adductus
. Varus
. Equinus
. Supination

Correct Answer & Explanation

. Equinus

Explanation

The Ponseti method corrects the components of clubfoot in a specific sequence summarized by the acronym CAVE: Cavus, Adductus, Varus, and finally Equinus. Equinus is typically corrected last and often requires a percutaneous Achilles tenotomy.

Question 6260

Topic: 4. Pediatrics

A 3-year-old child presents with a history of recurrent long bone fractures after minimal trauma, blue sclerae, and dentinogenesis imperfecta. A genetic defect in which of the following is most likely responsible for this condition?

. Fibroblast growth factor receptor 3 (FGFR3)
. Type I collagen (COL1A1 or COL1A2)
. Fibrillin-1 (FBN1)
. Cartilage oligomeric matrix protein (COMP)
. Core-binding factor alpha-1 (CBFA1/RUNX2)

Correct Answer & Explanation

. Type I collagen (COL1A1 or COL1A2)

Explanation

The clinical presentation is classic for Osteogenesis Imperfecta (OI). Approximately 90% of OI cases are caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, which encode Type I collagen.

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