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4. Pediatrics MCQs

Practice Set 235 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 4681

Topic: 4. Pediatrics

An 18-month-old male is evaluated for congenital pseudarthrosis of the tibia (CPT). Examination reveals anterolateral bowing of the affected leg. Which genetic condition is most strongly associated with this finding?

. Marfan Syndrome
. Ehlers-Danlos Syndrome
. Neurofibromatosis Type 1
. Achondroplasia
. Osteogenesis Imperfecta

Correct Answer & Explanation

. Marfan Syndrome

Explanation

Anterolateral bowing of the tibia and congenital pseudarthrosis of the tibia are classic musculoskeletal manifestations of Neurofibromatosis Type 1 (NF-1). Approximately 50% of patients with CPT have an underlying diagnosis of NF-1.

Question 4682

Topic: 4. Pediatrics

A newborn is diagnosed with achondroplasia. Which zone of the epiphyseal physis (growth plate) is primarily affected by the genetic mutation underlying this condition?

. Resting (Reserve) zone
. Proliferative zone
. Hypertrophic zone
. Zone of provisional calcification
. Primary spongiosa

Correct Answer & Explanation

. Resting (Reserve) zone

Explanation

Achondroplasia is caused by an activating mutation in the Fibroblast Growth Factor Receptor 3 (FGFR3) gene. This mutation primarily inhibits chondrocyte proliferation, thus affecting the proliferative zone of the physis and leading to rhizomelic dwarfism.

Question 4683

Topic: Pediatric Hip
A 9-year-old boy presents with a limp and groin pain. Radiographs demonstrate Legg-Calvé-Perthes disease classified as Lateral Pillar B. He has maintained good range of motion. What is the most appropriate surgical treatment to prevent femoral head deformation in this patient?
. In situ pinning of the femoral head
. Varus derotation osteotomy of the proximal femur
. Valgus extension osteotomy
. Core decompression of the femoral head
. Hip arthrodesis

Correct Answer & Explanation

. Varus derotation osteotomy of the proximal femur

Explanation

For patients older than 8 years with Lateral Pillar B or B/C border Legg-Calvé-Perthes disease, surgical containment yields better outcomes than nonoperative management. A varus derotation osteotomy (VDRO) centers the femoral head within the acetabulum to allow spherical remodeling.

Question 4684

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from monkey bars and sustains a widely displaced posterolateral Gartland type III supracondylar humerus fracture. Which of the following neurologic deficits is most likely to be observed on physical examination?
. Inability to extend the wrist and digits
. Inability to actively flex the distal interphalangeal joint of the index finger
. Decreased sensation over the dorsal first web space
. Inability to abduct and adduct the fingers
. Decreased sensation over the volar small finger

Correct Answer & Explanation

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

Explanation

Posterolateral displacement in supracondylar humerus fractures places the anterior interosseous nerve (AIN) at the greatest risk. AIN palsy presents with an inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger (the "OK" sign).

Question 4685

Topic: 4. Pediatrics
A 4-year-old girl is evaluated for severe bowing of her left leg. Radiographs reveal a prominent physeal step-off with depression of the medial tibial plateau, consistent with Langenskiöld stage IV infantile Blount's disease. What is the most appropriate management?
. Observation and yearly radiographic follow-up
. Knee-ankle-foot orthosis (KAFO) bracing during the day
. Proximal tibial valgus-derotation osteotomy
. Guided growth with a medial tension band plate
. Lateral proximal tibial epiphysiodesis

Correct Answer & Explanation

. Proximal tibial valgus-derotation osteotomy

Explanation

Bracing for infantile Blount's disease is generally ineffective after 3 years of age or in advanced stages (Langenskiöld III and above). A proximal tibial osteotomy is required to correct the severe multiplanar deformity and restore normal joint mechanics.

Question 4686

Topic: Pediatric Hip

A 12-year-old boy with a BMI in the 99th percentile presents with left knee pain and an inability to bear weight on his left leg. Radiographs confirm a severe Slipped Capital Femoral Epiphysis (SCFE). Which of the following factors is the greatest predictor for the development of avascular necrosis (AVN) in this patient?

. The chronicity of symptoms exceeding 3 months
. The severity of the slip angle on the lateral radiograph
. The patient's obesity percentile
. Inability to bear weight even with crutches
. Bilateral epiphyseal involvement

Correct Answer & Explanation

. The chronicity of symptoms exceeding 3 months

Explanation

The inability to bear weight defines an unstable SCFE, which carries a significantly higher risk of avascular necrosis (up to 47%) compared to stable slips. Slip severity or chronicity does not predict AVN as strongly as clinical stability.

Question 4687

Topic: Pediatric Hip
A 6-week-old female undergoes a screening hip ultrasound for breech presentation. The alpha angle is 45 degrees, and the beta angle is 80 degrees. According to the Graf classification, what is the most appropriate initial management?
. Application of a Pavlik harness
. Application of a rigid hip abduction orthosis
. Closed reduction and spica casting
. Open reduction and capsulorrhaphy
. Observation with repeat ultrasound in 4 weeks

Correct Answer & Explanation

. Application of a Pavlik harness

Explanation

An alpha angle of <50 degrees corresponds to a Graf Type III or severe Type IIc hip, indicating significant developmental dysplasia of the hip (DDH). The gold standard initial treatment for a child <6 months of age with DDH is a Pavlik harness.

Question 4688

Topic: Pediatric Lower Extremity
A 4-year-old boy with a history of idiopathic clubfoot treated successfully with the Ponseti method presents with a relapsed deformity. Gait analysis shows dynamic supination of the foot during the swing phase. Passive range of motion demonstrates a fully correctable deformity. What is the most appropriate surgical intervention?
. Repeat percutaneous Achilles tenotomy
. Split tibialis anterior tendon transfer (SPLATT)
. Full tibialis anterior tendon transfer to the lateral cuneiform
. Calcaneocuboid fusion
. Comprehensive posteromedial release

Correct Answer & Explanation

. Full tibialis anterior tendon transfer to the lateral cuneiform

Explanation

Dynamic supination during the swing phase in a relapsed, fully correctable clubfoot is best treated with a full tibialis anterior tendon transfer (TATT) to the lateral cuneiform. This balances the forefoot forces; a SPLATT is contraindicated in Ponseti relapses as it does not sufficiently address the deforming force.

Question 4689

Topic: 4. Pediatrics
A 13-year-old girl sustains an ankle injury during a soccer game. Radiographs reveal a Salter-Harris type III fracture of the anterolateral aspect of the distal tibial epiphysis (Tillaux fracture). This fracture pattern is primarily caused by an avulsion of which of the following structures?
. Anterior inferior tibiofibular ligament
. Posterior inferior tibiofibular ligament
. Anterior talofibular ligament
. Calcaneofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament

Explanation

A juvenile Tillaux fracture is an avulsion of the anterolateral distal tibial epiphysis caused by tension from the anterior inferior tibiofibular ligament (AITFL) during an external rotation injury. It occurs as the distal tibial physis closes from central to anterolateral.

Question 4690

Topic: Pediatric Hip
A 10-year-old boy with known Legg-Calvé-Perthes disease presents with increasing hip pain and stiffness. An arthrogram demonstrates "hinge abduction" with lateral subluxation of the femoral head against the acetabular rim during hip abduction. What is the most appropriate surgical treatment?
. Varus derotation osteotomy of the proximal femur
. Valgus extension intertrochanteric osteotomy
. Shelf acetabuloplasty
. Triple pelvic osteotomy
. Core decompression

Correct Answer & Explanation

. Valgus extension intertrochanteric osteotomy

Explanation

Hinge abduction occurs when an enlarged, deformed femoral head impinges on the lateral acetabular margin, preventing spherical containment. A valgus extension osteotomy redirects the head, moves the impingement away from the acetabular rim, and improves congruency.

Question 4691

Topic: 4. Pediatrics

A newborn infant is noted to have severe anterolateral bowing of the right tibia. There are no fractures present on initial radiographs. The infant is at highest risk for developing congenital pseudarthrosis of the tibia (CPT). Which of the following genetic conditions is most strongly associated with this finding?

. Osteogenesis Imperfecta (COL1A1 mutation)
. Achondroplasia (FGFR3 mutation)
. Neurofibromatosis type 1 (NF1 mutation)
. Multiple Hereditary Exostoses (EXT1 mutation)
. Pseudoachondroplasia (COMP mutation)

Correct Answer & Explanation

. Osteogenesis Imperfecta (COL1A1 mutation)

Explanation

Anterolateral bowing of the tibia is highly associated with congenital pseudarthrosis of the tibia (CPT). Approximately 50% of patients with CPT have a diagnosis of Neurofibromatosis type 1 (NF1), linked to chromosome 17q.

Question 4692

Topic: 4. Pediatrics

A 14-year-old elite baseball pitcher complains of insidious onset right shoulder pain during the cocking phase of throwing. Radiographs reveal widening and irregularity of the proximal humeral physis. What is the most appropriate initial management?

. Physical therapy focusing on rotator cuff strengthening
. Corticosteroid injection into the subacromial space
. Absolute rest from throwing for 3 months
. Surgical pinning of the proximal humeral physis
. Diagnostic shoulder arthroscopy

Correct Answer & Explanation

. Physical therapy focusing on rotator cuff strengthening

Explanation

Little Leaguer's shoulder (proximal humeral epiphysiolysis) is a stress fracture of the proximal humeral physis due to repetitive rotational forces. The gold standard treatment is complete cessation of throwing for typically 3 months, followed by a gradual return-to-throwing program.

Question 4693

Topic: 4. Pediatrics

A 7-year-old child with spastic quadriplegic cerebral palsy is evaluated during routine hip surveillance. Radiographs demonstrate a Reimers Migration Percentage of 45% in the right hip. The patient is non-ambulatory (GMFCS Level V) but experiences pain with diapering. What is the most recommended treatment?

. Observation and aggressive physical therapy
. Botulinum toxin injection to the adductor musculature
. Adductor and psoas tenotomies alone
. Varus derotation osteotomy of the proximal femur with or without pelvic osteotomy
. Total hip arthroplasty

Correct Answer & Explanation

. Observation and aggressive physical therapy

Explanation

In cerebral palsy, a migration percentage >40% typically indicates impending or true hip subluxation that will not resolve with soft-tissue release alone. Bony reconstruction with a varus derotation osteotomy (VDRO), often combined with a pelvic osteotomy, is required.

Question 4694

Topic: 4. Pediatrics

A 2-month-old infant is diagnosed with congenital muscular torticollis, presenting with a right sternocleidomastoid mass and the chin rotated to the left. Which of the following screening evaluations is strictly recommended for this infant?

. Renal ultrasound
. Echocardiogram
. Ultrasound of the hips
. MRI of the cervical spine
. Radiographs of the lower extremities

Correct Answer & Explanation

. Renal ultrasound

Explanation

Congenital muscular torticollis has a known association with Developmental Dysplasia of the Hip (DDH), with co-occurrence rates reported up to 20%. Therefore, an ultrasound of the hips is routinely recommended for early detection of DDH.

Question 4695

Topic: 4. Pediatrics

A 4-year-old boy with blue sclerae has sustained six fractures over the past two years with minimal trauma. Genetic testing confirms Osteogenesis Imperfecta (OI). The fundamental pathophysiology of his disease involves a defect in the synthesis of which of the following?

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

Correct Answer & Explanation

. Type II collagen

Explanation

Osteogenesis Imperfecta is primarily caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, which lead to quantitative or qualitative defects in Type I collagen, the major structural protein of bone.

Question 4696

Topic: Pediatric Upper Extremity & Spine
A 5-year-old girl undergoes closed reduction and percutaneous pinning for a Gartland type III supracondylar humerus fracture. Postoperatively, the radial pulse is completely absent, but her hand is warm, pink, and demonstrates brisk capillary refill (<2 seconds). What is the most appropriate management?
. Immediate exploration of the brachial artery
. Emergent fasciotomy of the forearm
. Observation with close monitoring and elevation
. Emergent angiography of the upper extremity
. Removal of all pins and conversion to open reduction

Correct Answer & Explanation

. Observation with close monitoring and elevation

Explanation

A "pink, pulseless" hand after anatomic reduction and stabilization of a supracondylar humerus fracture indicates adequate collateral circulation. The standard of care is close clinical observation, as the pulse typically returns within a few days due to resolution of vasospasm.

Question 4697

Topic: Pediatric Hip

A 12-year-old boy presents with a 3-week history of right hip pain and a limp. He is unable to bear weight on the right leg, even with crutches. Radiographs confirm a Slipped Capital Femoral Epiphysis (SCFE). According to the Loder classification, what is the most significant prognostic factor associated with this specific presentation?

. Development of chondrolysis
. Risk of contralateral slip
. Development of avascular necrosis (AVN)
. Progression of slip severity
. Premature physeal closure

Correct Answer & Explanation

. Development of chondrolysis

Explanation

The inability to bear weight defines an unstable SCFE according to the Loder classification. Unstable slips carry a significantly higher risk of developing avascular necrosis (up to 47%) compared to stable slips.

Question 4698

Topic: Pediatric Hip

An 8-year-old boy is diagnosed with Legg-Calve-Perthes disease. Radiographs show greater than 50% collapse of the lateral pillar of the femoral head. According to the Herring lateral pillar classification, what is his stage and expected prognosis?

. Group B; good prognosis with conservative care
. Group C; poor prognosis regardless of treatment
. Group B; favorable prognosis if surgical containment is performed
. Group C; excellent prognosis with immediate femoral osteotomy
. Group A; self-limiting condition requiring observation

Correct Answer & Explanation

. Group B; good prognosis with conservative care

Explanation

Herring Lateral Pillar Group C is defined by >50% loss of lateral pillar height. It is associated with a poor prognosis, particularly in children over 8 years of age, and often leads to a poorly spherical femoral head regardless of intervention.

Question 4699

Topic: Pediatric Hip

A 4-week-old female with an irreducible but dilatable left developmental dysplasia of the hip (DDH) is placed in a Pavlik harness. After 4 weeks of strictly compliant wear, dynamic ultrasound shows the hip remains completely dislocated. What is the most appropriate next step in management?

. Continue the Pavlik harness for another 4 weeks
. Adjust the harness straps to enforce maximum flexion and abduction
. Discontinue the Pavlik harness and transition to a rigid abduction orthosis or plan for closed reduction
. Perform an immediate open reduction
. Proceed directly to a pelvic (Salter) osteotomy

Correct Answer & Explanation

. Continue the Pavlik harness for another 4 weeks

Explanation

Continuing a Pavlik harness for a hip that remains dislocated after 3-4 weeks is contraindicated because it can cause 'Pavlik harness disease' due to posterior acetabular wear. The harness must be abandoned in favor of a rigid orthosis or closed reduction and spica casting.

Question 4700

Topic: 4. Pediatrics

A 3-year-old girl presents with progressive bilateral genu varum. Radiographs reveal a prominent medial metaphyseal beak and a sharp diaphyseal-metaphyseal angle. Which of the following is the most accurate statement regarding the suspected underlying pathology?

. It is a physiologic condition that self-resolves by age 5.
. It is caused by abnormal endochondral ossification at the lateral aspect of the proximal tibial physis.
. Obesity and early independent walking are well-established risk factors.
. The deformity is purely a varus angulation without any rotational components.
. Orthotic management is strictly contraindicated before the age of 4.

Correct Answer & Explanation

. It is a physiologic condition that self-resolves by age 5.

Explanation

Infantile Blount disease is characterized by disordered ossification of the medial aspect of the proximal tibial physis, causing varus, procurvatum, and internal rotation. Risk factors include obesity, African-American descent, and early walking.

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