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4. Pediatrics MCQs

Practice Set 255 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 5081

Topic: Pediatric Hip
According to the Herring lateral pillar classification for Legg-Calvé-Perthes disease, which of the following radiographic findings is the defining feature of a Group B hip?
. No involvement or collapse of the lateral pillar
. Greater than 50% maintenance of lateral pillar height
. Less than 50% maintenance of lateral pillar height
. Complete collapse of the lateral pillar
. Involvement of the medial pillar exclusively

Correct Answer & Explanation

. Greater than 50% maintenance of lateral pillar height

Explanation

In the Herring lateral pillar classification, Group A has no involvement of the lateral pillar. Group B maintains >50% of the lateral pillar height. Group C maintains <50% of the lateral pillar height. Group B/C is a borderline category. This classification is highly prognostic for the final hip outcome.

Question 5082

Topic: Pediatric Lower Extremity
A 3-year-old boy treated successfully for idiopathic clubfoot with the Ponseti method presents with a relapse. He demonstrates dynamic supination during the swing phase of gait without a fixed bony deformity. What is the most appropriate surgical management?
. Posteromedial soft tissue release
. Split anterior tibial tendon transfer (SPLATT)
. Transfer of the entire anterior tibial tendon to the third cuneiform
. Talonavicular arthrodesis
. Calcaneocuboid closing wedge osteotomy

Correct Answer & Explanation

. Transfer of the entire anterior tibial tendon to the third cuneiform

Explanation

Relapse in clubfoot often presents with dynamic supination due to an overpowering anterior tibial tendon in the setting of a corrected, but functionally weak, evertor complex. Transfer of the entire anterior tibial tendon to the third (lateral) cuneiform (TATT) is the treatment of choice for dynamic supination in a relapsed Ponseti-treated clubfoot in a child over 30 months of age.

Question 5083

Topic: 4. Pediatrics

A newborn is diagnosed with congenital fibular hemimelia. Which of the following associated anomalies is most commonly found in the ipsilateral limb?

. Absence of the medial rays of the foot
. Absence of the anterior cruciate ligament (ACL)
. Duplication of the thumb
. Proximal radioulnar synostosis
. Congenital vertical talus

Correct Answer & Explanation

. Absence of the medial rays of the foot

Explanation

Fibular hemimelia is a longitudinal deficiency associated with several ipsilateral limb anomalies, including absence of the lateral rays of the foot (not medial), anteromedial bowing of the tibia, limb length discrepancy, ball-and-socket ankle joint, and absence or hypoplasia of the anterior cruciate ligament (ACL).

Question 5084

Topic: Pediatric Upper Extremity & Spine
A newborn is noted to have severe radial deviation of the wrist with an absent thumb and shortened forearm. A screening echocardiogram reveals an atrial septal defect. Which of the following genetic conditions is most likely responsible?
. Fanconi anemia
. TAR (Thrombocytopenia-Absent Radius) syndrome
. Holt-Oram syndrome
. VACTERL association
. Apert syndrome

Correct Answer & Explanation

. Holt-Oram syndrome

Explanation

Holt-Oram syndrome is an autosomal dominant condition characterized by upper limb abnormalities (typically radial ray deficiencies, including an absent thumb) and congenital heart defects, most commonly an ASD or VSD. In TAR syndrome, the thumb is characteristically present despite an absent radius. Fanconi anemia is associated with aplastic anemia. VACTERL involves multiple organ systems but is less specific for this exact pairing without other findings.

Question 5085

Topic: 4. Pediatrics
A 13-year-old girl sustains a twisting ankle injury. Radiographs reveal a Salter-Harris III fracture of the anterolateral distal tibia. Which of the following best describes the physeal closure pattern of the distal tibia that directly predisposes her to this specific fracture pattern?
. Closes anteriorly first, then progresses posteriorly
. Closes laterally first, then progresses medially
. Closes centrally, then anteromedially, posteromedially, and finally laterally
. Closes centrally, then laterally, then medially
. Closes uniformly from peripheral to central

Correct Answer & Explanation

. Closes centrally, then anteromedially, posteromedially, and finally laterally

Explanation

The distal tibial physis closes over an 18-month period in a predictable sequence: it starts centrally, proceeds to the anteromedial portion, then posteromedial, and finally the lateral (anterolateral) portion closes last. Because the lateral physis remains open, the anterolateral epiphysis can be avulsed by the anterior inferior tibiofibular ligament, resulting in a Tillaux fracture.

Question 5086

Topic: 4. Pediatrics
A 4-year-old boy presents with progressive bilateral genu varum and lateral thrust during gait. Standing radiographs show an acute downward turning of the medial metaphysis of the proximal tibia with a metaphyseal-diaphyseal angle of 18 degrees. What is the most appropriate treatment?
. Reassurance and annual observation
. Knee-ankle-foot orthosis (KAFO) bracing for 23 hours a day
. Proximal tibial valgus-derotation osteotomy
. Guided growth with a medial tension band plate
. Epiphysiodesis of the lateral proximal tibia

Correct Answer & Explanation

. Proximal tibial valgus-derotation osteotomy

Explanation

This child has infantile Blount disease, indicated by a metaphyseal-diaphyseal angle > 16 degrees (Langenskiöld stage II or higher). Because the child is over the age of 3, bracing is generally ineffective and poorly tolerated. The definitive treatment for progressive infantile Blount disease in a child over age 3-4 is a proximal tibial valgus-derotation osteotomy.

Question 5087

Topic: 4. Pediatrics

In a 7-year-old non-ambulatory child with spastic quadriplegic cerebral palsy (GMFCS Level V), routine radiographic surveillance reveals a Reimer's migration percentage of 45% in the right hip. There is no subchondral sclerosis or joint space narrowing. What is the most appropriate recommendation?

. Continued radiographic surveillance every 2 years
. Botulinum toxin injections to the adductors
. Soft tissue release of the adductors and iliopsoas alone
. Varus derotational osteotomy (VDRO) of the proximal femur with or without pelvic osteotomy
. Femoral head resection (Castle procedure)

Correct Answer & Explanation

. Continued radiographic surveillance every 2 years

Explanation

In cerebral palsy, a Reimer's migration percentage > 40% typically indicates structural hip subluxation that will not respond reliably to soft tissue releases alone. Bony reconstruction with a Varus Derotational Osteotomy (VDRO), often combined with a pelvic osteotomy (e.g., Dega), is the standard of care to restore coverage and prevent painful dislocation.

Question 5088

Topic: 4. Pediatrics

A 10-year-old girl is found to have a post-traumatic physeal bar of the distal femur. A scanogram shows a 3 cm leg length discrepancy, and an MRI maps the bar as centrally located, occupying 30% of the cross-sectional area of the physis. She is expected to have 4 years of remaining growth. What is the most appropriate surgical management?

. Contralateral distal femoral epiphysiodesis
. Ipsilateral completion epiphysiodesis and lengthening over an intramedullary nail
. Resection of the physeal bar and interposition of an inert material
. Observation until skeletal maturity followed by a corrective osteotomy
. Medial and lateral guided growth using tension band plates

Correct Answer & Explanation

. Contralateral distal femoral epiphysiodesis

Explanation

Physeal bar resection is indicated if the bar occupies less than 50% of the cross-sectional area of the physis and the child has at least 2 years of remaining growth. Following resection, interposition with an inert material (such as autologous fat, Cranioplast, or bone wax) is critical to prevent the bar from reforming.

Question 5089

Topic: 4. Pediatrics
Which of the following classifications of Osteogenesis Imperfecta (OI) according to the Sillence criteria is characterized as uniformly lethal in the perinatal period?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type II

Explanation

Under the Sillence classification for Osteogenesis Imperfecta, Type II is the most severe form and is uniformly lethal in the perinatal period due to severe pulmonary hypoplasia and profound skeletal fragility resulting in multiple in utero fractures. Type I is mild, Type III is severe/progressive deforming, and Type IV is of moderate severity.

Question 5090

Topic: 4. Pediatrics

A 2-year-old boy with achondroplasia presents with a thoracolumbar kyphosis of 35 degrees. He has no neurologic deficits and has just started walking independently. What is the most appropriate management?

. Immediate posterior spinal fusion
. Anterior and posterior spinal fusion
. TLSO bracing for 23 hours a day
. Observation, as this typically resolves after independent ambulation begins
. Surgical decompression of the foramen magnum

Correct Answer & Explanation

. Immediate posterior spinal fusion

Explanation

Thoracolumbar kyphosis in infants and toddlers with achondroplasia is very common. It typically resolves spontaneously in the majority of patients once they begin walking independently and develop compensatory lumbar lordosis and hip extension. Observation is the most appropriate initial management unless the curve is fixed, severe, or associated with neurologic compromise.

Question 5091

Topic: Pediatric Hip

A 13-year-old boy underwent in situ single-screw fixation for a stable right Slipped Capital Femoral Epiphysis (SCFE) two years ago. He now complains of progressive right hip stiffness and worsening pain. Radiographs reveal global joint space narrowing to 1.5 mm, periarticular osteopenia, and no signs of avascular necrosis. What is the most likely diagnosis?

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

Correct Answer & Explanation

. Implant failure

Explanation

Chondrolysis is a devastating complication of SCFE, characterized by acute cartilage death and profound joint space narrowing (typically <3 mm). It presents with severe stiffness and pain. It has historically been associated with unrecognized screw penetration into the joint, severe slips, and prolonged spica casting. Radiographs classically show concentric joint space narrowing and periarticular osteopenia without collapse of the femoral head (which would indicate AVN).

Question 5092

Topic: 4. Pediatrics
A 4-year-old obese boy presents with Langenskiöld stage III infantile Blount disease. Conservative management with bracing has failed, and he demonstrates a worsening lateral thrust during gait. What is the most appropriate next step in management?
. Continue bracing until age 6
. Proximal tibial valgus osteotomy
. Medial plateau elevation
. Guided growth with lateral hemiepiphysiodesis
. Epiphysiodesis of the proximal tibia

Correct Answer & Explanation

. Proximal tibial valgus osteotomy

Explanation

Children over age 3 or those with Langenskiöld stage III or higher who fail bracing require surgical intervention. A proximal tibial valgus osteotomy is the gold standard to correct alignment and prevent further physeal damage.

Question 5093

Topic: Pediatric Hip
An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs demonstrate greater than 50% collapse of the lateral pillar of the femoral head. According to the Herring classification, what is his lateral pillar grade, and what is the expected outcome?
. Group A, with an excellent prognosis
. Group B, with a fair prognosis
. Group C, with a poor prognosis regardless of treatment
. Group B/C border, requiring immediate containment
. Group C, with an excellent prognosis following spica casting

Correct Answer & Explanation

. Group C, with a poor prognosis regardless of treatment

Explanation

Herring Group C is defined by greater than 50% loss of lateral pillar height. Patients in this group generally have a poor prognosis with a high likelihood of residual deformity, and surgical containment has limited benefit in older children.

Question 5094

Topic: Pediatric Lower Extremity

An infant with idiopathic clubfoot is undergoing Ponseti serial casting. After successfully correcting the cavus, adductus, and varus deformities, the foot remains in 15 degrees of rigid equinus. What is the next most appropriate step in management?

. Perform a posteromedial soft tissue release
. Continue weekly casting until equinus fully resolves
. Perform a percutaneous Achilles tenotomy
. Apply a Denis Browne splint immediately
. Perform an anterior tibial tendon transfer

Correct Answer & Explanation

. Perform a posteromedial soft tissue release

Explanation

The Ponseti method corrects deformities in the CAVE order: Cavus, Adductus, Varus, and Equinus. A percutaneous Achilles tenotomy is required in approximately 80% of cases to correct the residual rigid equinus.

Question 5095

Topic: 4. Pediatrics

A 2-week-old infant with arthrogryposis multiplex congenita presents with rigid, bilaterally dislocated hips. What is the most appropriate initial management strategy for the hip dysplasia in this patient?

. Immediate application of a Pavlik harness
. Closed reduction and spica casting
. Observation until 6 months of age followed by open reduction
. Botulinum toxin injections to the adductors
. Bilateral proximal femoral osteotomies

Correct Answer & Explanation

. Immediate application of a Pavlik harness

Explanation

Teratologic hip dislocations, such as those in arthrogryposis, are notoriously rigid and typically do not respond to a Pavlik harness. They usually require delay until the infant is older for a definitive open reduction, often with simultaneous femoral shortening.

Question 5096

Topic: Pediatric Lower Extremity

During the Ponseti method of serial casting for idiopathic clubfoot, the deformities must be corrected in a specific sequential order to avoid iatrogenic complications. Which deformity must be corrected first?

. Equinus
. Varus
. Adduction
. Cavus
. Internal tibial torsion

Correct Answer & Explanation

. Equinus

Explanation

The Ponseti method corrects deformities using the 'CAVE' sequence: Cavus, Adduction, Varus, and Equinus. The cavus is corrected first by supinating the forefoot to align it with the hindfoot.

Question 5097

Topic: Pediatric Hip

The Herring Lateral Pillar classification is used to determine the prognosis in Legg-Calve-Perthes disease. Which of the following radiographic parameters defines a Lateral Pillar Group C?

. > 50% maintenance of lateral pillar height on AP pelvis
. < 50% maintenance of lateral pillar height on AP pelvis
. Complete collapse of the central pillar on frog-leg lateral
. Epiphyseal extrusion > 20% on AP pelvis
. Subchondral fracture (Crescent sign) on frog-leg lateral

Correct Answer & Explanation

. > 50% maintenance of lateral pillar height on AP pelvis

Explanation

The Lateral Pillar classification evaluates the height of the lateral third of the femoral head on an AP radiograph during the fragmentation stage. Group C is defined as having less than 50% of the normal lateral pillar height maintained, which portends a poor prognosis.

Question 5098

Topic: Pediatric Hip

A 12-year-old boy undergoes in-situ percutaneous pinning for a stable slipped capital femoral epiphysis (SCFE). During the procedure, the surgeon fails to recognize intra-articular pin penetration. What is the most likely long-term complication?

. Avascular necrosis
. Coxa vara deformity
. Chondrolysis
. Femoroacetabular impingement
. Osteomyelitis

Correct Answer & Explanation

. Avascular necrosis

Explanation

Unrecognized intra-articular pin penetration is the primary cause of iatrogenic chondrolysis after SCFE fixation. Surgeons must utilize the 'approach-withdraw' principle on live fluoroscopy to ensure hardware does not breach the joint.

Question 5099

Topic: 4. Pediatrics
An adolescent sustains a triplane fracture of the distal tibia. Which combination of radiographic appearances classically characterizes this injury?
. Salter-Harris II on AP view, Salter-Harris I on lateral view
. Salter-Harris III on AP view, Salter-Harris II on lateral view
. Salter-Harris I on AP view, Salter-Harris IV on lateral view
. Salter-Harris IV on AP view, Salter-Harris III on lateral view
. Salter-Harris II on AP view, Salter-Harris III on lateral view

Correct Answer & Explanation

. Salter-Harris III on AP view, Salter-Harris II on lateral view

Explanation

A triplane fracture occurs during the asymmetric closure of the distal tibial physis. It classically appears as a Salter-Harris III fracture on the AP radiograph and a Salter-Harris II on the lateral radiograph.

Question 5100

Topic: Pediatric Lower Extremity

A 4-year-old boy presents with dynamic supination of the foot during the swing phase of gait. He was successfully treated for clubfoot as an infant using the Ponseti method. What is the treatment of choice for this specific relapse?

. Extensive posteromedial release
. Tibialis posterior tendon transfer
. Tibialis anterior tendon transfer (TATT) to the lateral cuneiform
. Repeat percutaneous Achilles tenotomy
. Calcaneal sliding osteotomy

Correct Answer & Explanation

. Extensive posteromedial release

Explanation

Dynamic supination during gait in a relapsed clubfoot is driven by an overactive tibialis anterior muscle. Transferring the tibialis anterior tendon to the lateral cuneiform redirects its force to assist in dorsiflexion without supinating the foot.

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