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4. Pediatrics MCQs

Practice Set 312 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 6221

Topic: 4. Pediatrics

A 22-year-old professional wide receiver suffers a severe hyperextension injury to his first metatarsophalangeal (MTP) joint, diagnosed as a "turf toe" injury. MRI reveals a Grade 3 injury. Which of the following is the most absolute indication for surgical repair rather than conservative management in this scenario?

. A capsular sprain without clinical instability
. Traumatic proximal migration of the sesamoids with gross MTP instability
. The presence of a congenital bipartite tibial sesamoid
. Mild dorsal osteophyte formation at the MTP joint
. A partial tear of the medial collateral ligament of the MTP joint

Correct Answer & Explanation

. Traumatic proximal migration of the sesamoids with gross MTP instability

Explanation

Operative intervention for turf toe (a plantar plate tear) is primarily indicated for Grade 3 injuries demonstrating gross instability, traumatic proximal migration of the sesamoids, or large intra-articular loose bodies. Lesser grades are managed non-operatively.

Question 6222

Topic: Pediatric Hip

A 12-year-old obese boy presents with left groin pain and an obligatory external rotation of the hip during flexion. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic in situ pinning of the asymptomatic contralateral hip?

. Age greater than 14 years
. Male sex
. Endocrine disorder (e.g., hypothyroidism)
. Body mass index > 95th percentile
. Presentation with an unstable slip

Correct Answer & Explanation

. Endocrine disorder (e.g., hypothyroidism)

Explanation

Correct Answer: Endocrine disorder (e.g., hypothyroidism)Patients with endocrine disorders (such as hypothyroidism, renal osteodystrophy, or growth hormone deficiency) have a significantly higher risk of developing bilateral SCFE, often presenting at an atypical age. Prophylactic pinning of the contralateral hip is highly recommended in this population to prevent future displacement and associated complications.

Question 6223

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 right leg. On examination, there is absent active knee extension on the right, but ankle and toe movements are normal. What is the most likely cause of this finding?

. Excessive flexion of the anterior straps causing femoral nerve palsy
. Excessive abduction of the posterior straps causing obturator nerve palsy
. Inadequate flexion of the anterior straps causing sciatic nerve palsy
. Avascular necrosis of the femoral head
. Septic arthritis of the hip

Correct Answer & Explanation

. Excessive flexion of the anterior straps causing femoral nerve palsy

Explanation

Correct Answer: Excessive flexion of the anterior straps causing femoral nerve palsyFemoral nerve palsy is a known complication of Pavlik harness treatment, typically caused by excessive hyperflexion of the hip due to the anterior straps being too tight. It presents with decreased or absent active knee extension. If this occurs, the harness should be adjusted to reduce flexion or temporarily discontinued until nerve function returns.

Question 6224

Topic: Pediatric Lower Extremity

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

. Cavus, Adduction, Varus, Equinus
. Equinus, Varus, Adduction, Cavus
. Cavus, Varus, Adduction, Equinus
. Adduction, Varus, Cavus, Equinus
. Varus, Cavus, Adduction, Equinus

Correct Answer & Explanation

. Cavus, Adduction, Varus, Equinus

Explanation

Correct Answer: Cavus, Adduction, 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 (which often requires a percutaneous Achilles tenotomy as the final step).

Question 6225

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Which of the following radiographic findings is considered a 'head-at-risk' sign according to Catterall, indicating a poorer prognosis?
. Medial subluxation of the femoral head
. Gage sign (V-shaped radiolucency in the lateral epiphysis)
. Ossification of the capital femoral epiphysis
. Narrowing of the medial joint space
. Hypertrophy of the greater trochanter

Correct Answer & Explanation

. Gage sign (V-shaped radiolucency in the lateral epiphysis)

Explanation

Catterall described several 'head-at-risk' signs for Perthes disease that correlate with a poorer prognosis and potential for hinge abduction. These include Gage sign (a V-shaped radiolucency in the lateral portion of the epiphysis and adjacent metaphysis), lateral subluxation of the femoral head, calcification lateral to the epiphysis, and a horizontal growth plate.

Question 6226

Topic: 4. Pediatrics

In a child with cerebral palsy, which of the following factors is the most significant predictor for the development of hip displacement (subluxation or dislocation)?

. Gross Motor Function Classification System (GMFCS) level
. Type of movement disorder (spastic vs. dyskinetic)
. Age at diagnosis
. Presence of upper extremity contractures
. History of selective dorsal rhizotomy

Correct Answer & Explanation

. Gross Motor Function Classification System (GMFCS) level

Explanation

Correct Answer: Gross Motor Function Classification System (GMFCS) levelThe GMFCS level is the most reliable and significant predictor of hip displacement in children with cerebral palsy. There is a direct linear relationship: children with higher GMFCS levels (IV and V), who are non-ambulatory, have the highest risk of hip subluxation and dislocation, necessitating strict and frequent radiographic surveillance.

Question 6227

Topic: Pediatric Hip

A 12-year-old obese boy presents with left groin pain and an obligatory external rotation of the hip during flexion. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic pinning of the contralateral asymptomatic hip?

. Age greater than 14 years
. Underlying endocrine disorder
. Male sex
. Grade I slip on the symptomatic side
. BMI greater than the 95th percentile

Correct Answer & Explanation

. Underlying endocrine disorder

Explanation

Correct Answer: Underlying endocrine disorderProphylactic pinning of the contralateral hip in SCFE is highly recommended in patients with underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) due to the significantly increased risk of bilateral involvement. While obesity and young age (e.g., males < 12, females < 10) are also risk factors for bilaterality, an underlying endocrinopathy is the strongest absolute indication for prophylactic fixation.

Question 6228

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 treated side. On examination, there is an absence of active knee extension. What is the most appropriate next step in management?

. Adjust the anterior straps to increase hip flexion
. Adjust the posterior straps to increase hip abduction
. Remove the harness and observe
. Transition to a rigid abduction orthosis
. Perform an immediate closed reduction and spica casting

Correct Answer & Explanation

. Remove the harness and observe

Explanation

Correct Answer: Remove the harness and observeThe clinical presentation is consistent with a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The femoral nerve becomes compressed against the rim of the pelvis. The most appropriate next step is to remove the harness and observe until neurologic function returns, which typically occurs within a few days to weeks. Continuing the harness or increasing flexion can lead to permanent nerve damage or failure of treatment.

Question 6229

Topic: Pediatric Lower Extremity

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

. Cavus, Adductus, Varus, Equinus
. Equinus, Varus, Adductus, Cavus
. 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 the deformities of clubfoot in a specific sequence summarized 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 if dorsiflexion to 15 degrees cannot be achieved through casting alone.

Question 6230

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 tibial epiphysis. Which ligament is responsible for the avulsion of this fracture fragment?
. Anterior talofibular ligament
. Calcaneofibular ligament
. Anterior inferior tibiofibular ligament
. Posterior inferior tibiofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament

Explanation

A 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 lateral. An external rotation force causes the anterior inferior tibiofibular ligament (AITFL) to avulse the unfused anterolateral epiphysis.

Question 6231

Topic: Pediatric Hip

In the evaluation of Legg-Calve-Perthes disease, the lateral pillar classification is used to determine prognosis. During which stage of the disease is this classification most accurately applied?

. Initial (necrosis) stage
. Fragmentation stage
. Reossification stage
. Remodeling stage
. Residual stage

Correct Answer & Explanation

. Fragmentation stage

Explanation

Correct Answer: Fragmentation stageThe Herring lateral pillar classification is most accurately applied during the early fragmentation stage of Legg-Calve-Perthes disease. It assesses the height of the lateral pillar of the capital femoral epiphysis on an AP radiograph. A lateral pillar height of >100% is Group A, >50% is Group B, and <50% is Group C. This classification correlates strongly with the long-term outcome and risk of aspherical femoral head development.

Question 6232

Topic: 4. Pediatrics

A 4-year-old girl with frequent fractures, blue sclerae, and dentinogenesis imperfecta is diagnosed with Osteogenesis Imperfecta. This condition is most commonly caused by a mutation affecting which of the following?

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

Correct Answer & Explanation

. Type I collagen

Explanation

Correct Answer: Type I collagenOsteogenesis Imperfecta (OI) 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. Type I collagen is the major structural protein in bone, sclerae, and dentin, explaining the classic triad of brittle bones, blue sclerae, and dentinogenesis imperfecta. FGFR3 mutations cause achondroplasia, and COMP mutations cause pseudoachondroplasia or multiple epiphyseal dysplasia.

Question 6233

Topic: 4. Pediatrics

In a child with spastic quadriplegic cerebral palsy (GMFCS Level V), what is the most critical radiographic parameter to monitor during routine hip surveillance to prevent hip dislocation?

. Acetabular index
. Center-edge angle of Wiberg
. Reimer's migration percentage
. Alpha angle
. Neck-shaft angle

Correct Answer & Explanation

. Reimer's migration percentage

Explanation

Correct Answer: Reimer's migration percentageReimer's migration percentage is the most critical radiographic parameter used in hip surveillance for children with cerebral palsy. It measures the percentage of the femoral head that is laterally displaced outside the ossified acetabular roof (Perkin's line). A migration percentage greater than 30% indicates subluxation and often warrants closer monitoring or prophylactic surgical intervention (e.g., adductor release or varus derotational osteotomy).

Question 6234

Topic: 4. Pediatrics
A 3-year-old girl presents with progressive bilateral genu varum. Radiographs reveal a sharp varus angulation at the proximal tibial metaphysis with medial beaking. According to the Langenskiold classification, which radiographic feature defines Stage IV infantile Blount disease?
. Irregularity of the metaphyseal beak
. A sharp depression of the medial metaphyseal beak
. Stepping of the medial physis with a bony bridge forming across the physis
. Closure of the medial physis with an established bony bar
. Restoration of the normal physeal architecture

Correct Answer & Explanation

. Closure of the medial physis with an established bony bar

Explanation

In the Langenskiold classification of infantile Blount disease, Stage IV is characterized by the closure of the medial physis and the formation of an established bony bar (epiphyseometaphyseal bridge). Stage I shows metaphyseal beaking, Stage II shows a sharp depression, Stage III shows 'stepping' of the metaphysis, Stage V shows a cleft in the epiphysis, and Stage VI shows a fully formed medial physeal bar with severe deformity.

Question 6235

Topic: Pediatric Hip
A 12-year-old boy with a BMI in the 99th percentile undergoes in situ pinning for a stable left slipped capital femoral epiphysis (SCFE). Which of the following is the most widely accepted indication for prophylactic pinning of the contralateral asymptomatic hip?
. Age greater than 14 years
. Presence of an endocrine disorder (e.g., hypothyroidism)
. Female sex
. Grade III slip on the affected side
. Presentation with knee pain rather than hip pain

Correct Answer & Explanation

. Presence of an endocrine disorder (e.g., hypothyroidism)

Explanation

Prophylactic pinning of the contralateral hip in SCFE remains a topic of debate, but it is generally recommended for patients at high risk for bilateral involvement. High-risk factors include the presence of an endocrine disorder (such as hypothyroidism, renal osteodystrophy, or panhypopituitarism), previous radiation therapy, and young age at presentation (typically less than 10 years old for boys). Older age, severity of the initial slip, and presentation with knee pain do not independently mandate prophylactic contralateral pinning.

Question 6236

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 an absence of active knee extension. What is the most appropriate next step in management?

. Adjust the anterior straps to increase hip flexion
. Adjust the posterior straps to increase hip abduction
. Discontinue the Pavlik harness immediately
. Switch to a rigid hip spica cast
. Order an urgent MRI of the lumbar spine

Correct Answer & Explanation

. Discontinue the Pavlik harness immediately

Explanation

Correct Answer: Discontinue the Pavlik harness immediatelyThe clinical presentation describes a femoral nerve palsy, which is a known complication of excessive hip flexion in a Pavlik harness. The femoral nerve becomes compressed against the rim of the pelvis or the inguinal ligament. The appropriate management is to discontinue the harness (or significantly loosen the anterior straps to reduce hip flexion) to relieve the pressure on the nerve. Most cases resolve spontaneously within a few days to weeks after removing the hyperflexion force. Continuing the harness or switching to a spica cast without allowing nerve recovery is contraindicated.

Question 6237

Topic: Pediatric Lower Extremity

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

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

Correct Answer & Explanation

. Cavus, Varus, Adductus, Equinus

Explanation

Correct Answer: Cavus, Adductus, Varus, EquinusThe Ponseti method corrects clubfoot deformities in a specific, sequential order summarized by the acronym CAVE: Cavus, Adductus, Varus, and Equinus. The first step is to correct the cavus by elevating the first ray to align the forefoot with the hindfoot. Subsequent casts correct the adductus and varus by abducting the foot around the head of the talus. Finally, the equinus is corrected, which often requires a percutaneous Achilles tenotomy.

Question 6238

Topic: Pediatric Hip
In the evaluation of a 7-year-old boy with Legg-Calvé-Perthes disease, which of the following radiographic classification systems is most predictive of the long-term outcome and risk of early osteoarthritis?
. Catterall classification
. Salter-Thompson classification
. Herring Lateral Pillar classification
. Waldenström classification
. Stulberg classification

Correct Answer & Explanation

. Herring Lateral Pillar classification

Explanation

The Herring Lateral Pillar classification, assessed during the fragmentation phase of Legg-Calvé-Perthes disease, is the most reliable and widely used prognostic indicator. It evaluates the height of the lateral pillar of the femoral head (Group A: >100% height maintained; Group B: >50% height maintained; Group C: <50% height maintained). The Stulberg classification is used at skeletal maturity to assess the final joint congruency, not during the active disease process. Waldenström describes the temporal stages of the disease.

Question 6239

Topic: 4. Pediatrics

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

. Observation and repeat radiographs in 1 year
. Botulinum toxin injections to the adductors
. Bilateral adductor tenotomies alone
. Bilateral varus derotational osteotomies (VDRO) and pelvic osteotomies
. Bilateral proximal femoral resection (Girdlestone)

Correct Answer & Explanation

. Bilateral varus derotational osteotomies (VDRO) and pelvic osteotomies

Explanation

Correct Answer: Bilateral varus derotational osteotomies (VDRO) and pelvic osteotomiesIn a child with cerebral palsy, a Reimers migration percentage greater than 40-50% indicates significant hip subluxation with a high risk of progression to dislocation. In a 6-year-old child, soft tissue releases alone (such as adductor tenotomies) are generally insufficient to halt or reverse the progression when the migration percentage is this high. Bony reconstruction, typically consisting of a proximal femoral varus derotational osteotomy (VDRO) combined with a pelvic osteotomy (e.g., Dega or San Diego), is the standard of care to stabilize the hip and prevent painful dislocation.

Question 6240

Topic: 4. Pediatrics

A 4-year-old boy presents with multiple fractures after 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 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 collagenThe clinical presentation of multiple fragility fractures, blue sclerae, and dentinogenesis imperfecta is classic for Osteogenesis Imperfecta (OI). OI is most commonly caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, which encode the alpha-1 and alpha-2 chains of Type I collagen. Type I collagen is the major structural protein in bone, sclera, dentin, and ligaments. Type II collagen mutations cause skeletal dysplasias like achondrogenesis or SED. Fibrillin-1 is associated with Marfan syndrome, FGFR3 with achondroplasia, and COMP with pseudoachondroplasia.

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