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4. Pediatrics MCQs

Practice Set 259 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 5161

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a completely displaced, extension-type supracondylar humerus fracture. After closed reduction and percutaneous pinning, his hand remains pink but pulseless. What is the next best step in management?

. Immediate open vascular exploration
. Observation with close clinical monitoring
. Emergent arteriography
. Remove pins and attempt open reduction
. Administer intravenous thrombolytics

Correct Answer & Explanation

. Immediate open vascular exploration

Explanation

A well-perfused (pink) but pulseless hand after adequate reduction and pinning of a supracondylar fracture indicates collateral circulation is intact. Close clinical observation is the standard of care, as the palpable pulse typically returns within a few days.

Question 5162

Topic: Pediatric Hip
An 8-year-old boy with Legg-Calvé-Perthes disease is evaluated radiographically. According to the modified lateral pillar (Herring) classification, which finding portends the worst prognosis?
. Greater than 50% maintained lateral pillar height
. Less than 50% maintained lateral pillar height
. Fragmentation of the medial pillar
. Presence of a Gage sign
. Calcification lateral to the epiphysis

Correct Answer & Explanation

. Less than 50% maintained lateral pillar height

Explanation

The Herring (lateral pillar) classification is highly prognostic in Legg-Calvé-Perthes disease. Group C, defined as having less than 50% of the lateral pillar height maintained, predicts a poor radiographic and clinical outcome, particularly in children over 8 years old.

Question 5163

Topic: 4. Pediatrics
A 13-year-old girl sustains a Salter-Harris III fracture of the anterolateral distal tibial epiphysis (Tillaux fracture). 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 avulsion fracture of the anterolateral distal tibial epiphysis. The mechanism involves external rotation of the foot, causing the anterior inferior tibiofibular ligament (AITFL) to avulse the unfused lateral fragment.

Question 5164

Topic: Pediatric Hip

A 3-year-old girl is diagnosed with untreated developmental dysplasia of the hip (DDH). Radiographs reveal a completely dislocated left hip with a false acetabulum. What is the most appropriate surgical management at this age?

. Closed reduction and spica casting
. Open reduction and spica casting
. Open reduction, femoral shortening osteotomy, and pelvic osteotomy
. Pelvic osteotomy alone
. Observation until skeletal maturity

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

In children over 2 to 3 years of age, soft tissue contractures and acetabular dysplasia require an open reduction combined with a femoral shortening osteotomy (to reduce joint pressure and AVN risk) and a pelvic osteotomy (to improve acetabular coverage).

Question 5165

Topic: 4. Pediatrics
A 13-year-old girl sustains an ankle injury while playing soccer. Radiographs show a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. What is the primary mechanism of injury for this specific fracture pattern?
. Supination-adduction
. External rotation of the foot relative to the leg
. Axial loading
. Plantar flexion and inversion
. Direct valgus trauma

Correct Answer & Explanation

. External rotation of the foot relative to the leg

Explanation

This describes a juvenile Tillaux fracture, which occurs due to an external rotation force. The anterior inferior tibiofibular ligament (AITFL) pulls and avulses the anterolateral epiphysis, which is the last portion of the distal tibial physis to close.

Question 5166

Topic: Pediatric Hip

A 14-year-old boy undergoes percutaneous in situ pinning for a stable Slipped Capital Femoral Epiphysis (SCFE). Six months later, he presents with severe hip stiffness, pain, and a significant loss of internal rotation and abduction. Radiographs show concentric joint space narrowing of the affected hip. What is the most likely diagnosis?

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

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

Concentric joint space narrowing and stiffness following SCFE, especially if a pin penetrated the joint space during surgery, is the hallmark of chondrolysis. Avascular necrosis typically presents with subchondral collapse rather than diffuse joint space loss.

Question 5167

Topic: 4. Pediatrics

A 6-year-old boy with spastic quadriplegic cerebral palsy has a hip migration percentage of 60% on anteroposterior pelvis radiography. The hip is subluxated but reducible. What is the most appropriate surgical intervention?

. Adductor tenotomy alone
. Botulinum toxin injection to the adductors
. Varus derotation osteotomy (VDRO) of the proximal femur with pelvic osteotomy
. Proximal femoral resection (Girdlestone procedure)
. Observation and repeat radiographs in 6 months

Correct Answer & Explanation

. Adductor tenotomy alone

Explanation

A migration percentage greater than 50% in a child with spastic CP indicates severe hip subluxation. Bony reconstruction with a proximal femoral varus derotation osteotomy (VDRO) and a concurrent pelvic osteotomy is the gold standard to achieve a stable, congruent hip.

Question 5168

Topic: Pediatric Hip

Which of the following is the primary basis for the Herring Lateral Pillar classification used in Legg-Calve-Perthes disease?

. The degree of subchondral radiolucency (Crescent sign)
. The height of the lateral third of the capital femoral epiphysis on an AP radiograph
. The presence of lateral calcification or ossification in the soft tissues
. The amount of epiphyseal extrusion on a Lauenstein lateral radiograph
. The extent of metaphyseal cyst formation

Correct Answer & Explanation

. The degree of subchondral radiolucency (Crescent sign)

Explanation

The Herring Lateral Pillar classification is based on the height of the lateral pillar of the capital femoral epiphysis on an AP radiograph during the early fragmentation phase. It is the most reliable prognostic indicator for late outcomes.

Question 5169

Topic: Pediatric Upper Extremity & Spine

A 13-year-old girl is diagnosed with adolescent idiopathic scoliosis (AIS). She is pre-menarchal, Risser 0, with a right thoracic curve of 35 degrees. What is the most appropriate management?

. Observation with follow-up radiographs in 1 year
. Physical therapy and core strengthening
. Full-time Thoracolumbosacral orthosis (TLSO) bracing
. Posterior spinal fusion
. Anterior tethering procedure

Correct Answer & Explanation

. Observation with follow-up radiographs in 1 year

Explanation

TLSO bracing is indicated for growing children (Risser 0-2, pre-menarchal) with an AIS curve between 25 and 45 degrees. Her high risk of progression makes immediate full-time bracing the standard of care.

Question 5170

Topic: 4. Pediatrics

During the Ponseti casting technique for a rigid congenital clubfoot, what is the most likely complication if forceful dorsiflexion is attempted before the heel varus and forefoot supination are fully corrected?

. Avascular necrosis of the talus
. Tibial torsion
. Rocker-bottom foot deformity
. Premature closure of the distal tibial physis
. Navicular subluxation

Correct Answer & Explanation

. Avascular necrosis of the talus

Explanation

Attempting to correct equinus by dorsiflexing the foot before correcting the cavus, adductus, and heel varus causes a midfoot break, clinically presenting as a rocker-bottom foot deformity.

Question 5171

Topic: Pediatric Hip

In a 7-year-old boy diagnosed with Legg-Calve-Perthes disease, which of the following radiographic findings is considered the most reliable indicator of a poor prognosis according to the Herring classification?

. Gage sign
. Calcification lateral to the epiphysis
. Metaphyseal cysts
. Less than 50% maintenance of the lateral pillar height
. Subchondral fracture line (crescent sign)

Correct Answer & Explanation

. Gage sign

Explanation

The Herring Lateral Pillar classification is the most reliable prognostic indicator for Legg-Calve-Perthes disease. Group C, which involves greater than 50% collapse of the lateral pillar, portends a poor clinical outcome.

Question 5172

Topic: Pediatric Upper Extremity & Spine
A 5-year-old boy presents with an extension-type Gartland III supracondylar humerus fracture. Examination reveals a "pink, pulseless" hand. Following closed reduction and percutaneous pinning, the hand remains pink and pulseless. What is the most appropriate next step in management?
. Immediate open exploration of the brachial artery
. Observation and admission for 24-48 hours
. Administration of intravenous heparin
. Performing a fasciotomy of the forearm
. Performing an arterial duplex ultrasound

Correct Answer & Explanation

. Observation and admission for 24-48 hours

Explanation

A well-perfused (pink) but pulseless hand after adequate reduction of a supracondylar fracture typically has adequate collateral circulation and can be observed closely. Open exploration is indicated if the hand is persistently white, cold, and pulseless after reduction.

Question 5173

Topic: Pediatric Hip

A 3-year-old girl is undergoing surgical treatment for developmental dysplasia of the hip (DDH). The surgeon plans a pelvic osteotomy that involves an incomplete osteotomy of the ilium leaving the sciatic notch intact, hinging on the triradiate cartilage to improve anterolateral coverage. Which osteotomy is being described?

. Salter
. Pemberton
. Dega
. Chiari
. Steel

Correct Answer & Explanation

. Salter

Explanation

The Pemberton osteotomy is an incomplete pericapsular osteotomy that hinges on the flexible triradiate cartilage. It primarily improves anterolateral acetabular coverage without disrupting the sciatic notch and decreases acetabular volume.

Question 5174

Topic: 4. Pediatrics

A 2.5-year-old obese girl presents with bilateral severe genu varum. Radiographs show medial metaphyseal beaking and an abnormal metaphyseal-diaphyseal angle of 18 degrees. What is the most appropriate initial treatment?

. Observation and reassurance
. Proximal tibial valgus osteotomy
. Knee-ankle-foot orthoses (KAFOs)
. Guided growth with tension band plates
. Guided growth with transphyseal screws

Correct Answer & Explanation

. Observation and reassurance

Explanation

Infantile Blount disease (Langenskiold stages I-II in children < 3 years old with a metaphyseal-diaphyseal angle > 16 degrees) is initially treated with KAFOs. Surgery is reserved for failure of brace treatment or in older children.

Question 5175

Topic: 4. Pediatrics

A 6-year-old child with spastic quadriplegic cerebral palsy has a Gross Motor Function Classification System (GMFCS) level of V. What is the recommended frequency for radiographic hip surveillance in this patient?

. Radiographs at age 2, then only if symptomatic
. Annual radiographs until skeletal maturity
. Radiographs every 6 months until age 7, then annually
. Single radiograph at age 5
. No routine radiographs recommended

Correct Answer & Explanation

. Radiographs at age 2, then only if symptomatic

Explanation

Patients with GMFCS level V are at the highest risk for hip displacement (up to 90%). Surveillance guidelines recommend clinical exams and AP pelvis radiographs every 6 months until age 7, and then annually until skeletal maturity.

Question 5176

Topic: 4. Pediatrics
A 4-year-old boy previously treated for bilateral idiopathic clubfeet with the Ponseti method presents with dynamic supination of the feet during the swing phase of gait. Passive range of motion is full, and there is no fixed deformity. What is the most appropriate surgical intervention?
. Achilles tendon lengthening
. Posteromedial release
. Split tibialis anterior tendon transfer (SPLATT)
. Complete tibialis anterior tendon transfer to the lateral cuneiform
. Plantar fasciotomy

Correct Answer & Explanation

. Complete tibialis anterior tendon transfer to the lateral cuneiform

Explanation

Dynamic supination in a previously treated clubfoot with flexible joints is best treated with a complete tibialis anterior tendon transfer to the third (lateral) cuneiform. A split transfer (SPLATT) is typically reserved for spastic conditions like cerebral palsy.

Question 5177

Topic: Pediatric Hip

A 13-year-old boy undergoes in situ single-screw fixation for a stable slipped capital femoral epiphysis (SCFE). Which intraoperative technical error is most strongly associated with the development of chondrolysis?

. Pinning the contralateral prophylactic hip
. Penetration of the screw into the joint space
. Placing the screw in the anterior half of the epiphysis
. Using a fully threaded screw instead of a partially threaded screw
. Starting the screw distal to the intertrochanteric line

Correct Answer & Explanation

. Pinning the contralateral prophylactic hip

Explanation

Unrecognized intraoperative joint penetration by the guidewire or screw is the most common iatrogenic cause of chondrolysis in SCFE treatment. An intraoperative "approach-withdraw" fluoroscopic technique is used to prevent this complication.

Question 5178

Topic: Pediatric Upper Extremity & Spine

A 13-year-old premenarchal female with Risser stage 0 presents with adolescent idiopathic scoliosis. Her right thoracic curve measures 32 degrees on standing PA radiographs. What is the most appropriate management?

. Observation with radiographs in 6 months
. Full-time use of a Thoracolumbosacral Orthosis (TLSO)
. Posterior spinal fusion
. Anterior tethering procedure
. Physical therapy and core strengthening

Correct Answer & Explanation

. Observation with radiographs in 6 months

Explanation

Bracing is indicated in skeletally immature patients (Risser 0-2, premenarchal) with curves between 25 and 40 degrees. A TLSO worn >18 hours/day significantly decreases the risk of curve progression to surgical thresholds.

Question 5179

Topic: 4. Pediatrics
A 10-year-old boy sustains an injury to his distal radius. Radiographs demonstrate a fracture line propagating through the physis and exiting through the metaphysis, leaving a triangular metaphyseal fragment attached to the epiphysis. What Salter-Harris classification represents this injury?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type II

Explanation

A Salter-Harris Type II fracture goes through the physis and exits through the metaphysis, carrying a metaphyseal fragment (Thurston-Holland fragment). It is the most common type of pediatric physeal fracture.

Question 5180

Topic: 4. Pediatrics

A 12-year-old boy presents with multiple bony prominences around his knees and wrists, associated with bowing of the forearms. Genetic testing reveals a mutation in the EXT1 gene. This mutation primarily disrupts the synthesis of which of the following extracellular matrix components?

. Type II collagen
. Fibroblast growth factor receptor 3 (FGFR3)
. Heparan sulfate
. Chondroitin sulfate
. Matrix metalloproteinases

Correct Answer & Explanation

. Heparan sulfate

Explanation

The patient has Multiple Hereditary Exostoses (MHE) or osteochondromatosis. It is inherited in an autosomal dominant pattern and caused by mutations in the EXT1 or EXT2 genes. These genes encode glycosyltransferases essential for the biosynthesis of heparan sulfate. The resulting deficiency in heparan sulfate proteoglycans disrupts normal Indian hedgehog (Ihh) signaling at the growth plate, leading to osteochondroma formation.

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