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4. Pediatrics MCQs

Practice Set 24 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 461

Topic: Pediatric Hip

A 6-month-old infant with developmental dysplasia of the hip (DDH) is being evaluated for closed reduction. A pre-procedural arthrogram demonstrates an "hourglass" constriction of the capsule. Which anatomical structure is responsible for this constriction?

. Ligamentum teres
. Transverse acetabular ligament
. Iliopsoas tendon
. Reflected head of the rectus femoris
. Gluteus medius tendon

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

In long-standing DDH, the capsular constriction that creates the classic "hourglass" appearance on arthrography is caused by the tight iliopsoas tendon crossing over the anterior capsule.

Question 462

Topic: Pediatric Lower Extremity

A 5-year-old boy presents with a prominent bump on the medial aspect of his foot and in-toeing. Clinical examination reveals a "Z-foot" deformity. He has a history of treated clubfoot. What is the primary pathoanatomy of the "skewfoot" deformity?

. Metatarsus adductus, normal midfoot, and hindfoot varus
. Metatarsus adductus, midfoot lateral translation, and hindfoot valgus
. Metatarsus valgus, midfoot medial translation, and hindfoot varus
. Forefoot supination, midfoot cavus, and hindfoot equinus
. Metatarsus primus varus, midfoot normal, and hindfoot equinovarus

Correct Answer & Explanation

. Metatarsus adductus, midfoot lateral translation, and hindfoot valgus

Explanation

Skewfoot (or Z-foot) is a complex deformity characterized by severe metatarsus adductus, lateral translation/abduction of the midfoot at the Chopart joint, and hindfoot valgus.

Question 463

Topic: 4. Pediatrics

According to the Ponseti method for the treatment of congenital talipes equinovarus, what is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The correct sequence of correction in the Ponseti method follows the acronym CAVE: Cavus, Adductus, Varus, and finally Equinus. The cavus is corrected first by supinating the forefoot to align it with the hindfoot.

Question 464

Topic: 4. Pediatrics

A newborn is diagnosed with diastrophic dysplasia. Which of the following genetic mutations is responsible for this condition?

. FGFR3
. COL1A1
. SLC26A2
. COMP
. RUNX2

Correct Answer & Explanation

. SLC26A2

Explanation

Diastrophic dysplasia is an autosomal recessive condition caused by mutations in the SLC26A2 gene, which encodes a sulfate transporter. Clinical features include hitchhiker thumbs, cauliflower ears, and severe cervical kyphosis.

Question 465

Topic: 4. Pediatrics

Which of the following clinical findings is most characteristically associated with fibular hemimelia?

. Posteromedial bowing of the tibia
. Anterolateral bowing of the tibia
. Anteromedial bowing of the tibia
. Oligodactyly of the medial rays
. Syndactyly of the first web space

Correct Answer & Explanation

. Anteromedial bowing of the tibia

Explanation

Fibular hemimelia is characteristically associated with anteromedial bowing of the tibia, shortening of the limb, a ball-and-socket ankle joint, and absence of lateral foot rays. Anterolateral bowing is associated with congenital pseudarthrosis of the tibia.

Question 466

Topic: Pediatric Lower Extremity

A 4-year-old child successfully treated for bilateral idiopathic clubfeet with the Ponseti method presents with a dynamic supination deformity of the foot during the swing phase of gait. Passive range of motion is full. What is the most appropriate management?

. Posteromedial release
. Repeat serial casting
. Tibialis anterior tendon transfer
. Achilles tendon lengthening
. Split tibialis posterior tendon transfer

Correct Answer & Explanation

. Tibialis anterior tendon transfer

Explanation

Dynamic supination during the swing phase in a toddler previously treated for clubfoot is best managed by transferring the tibialis anterior tendon to the third cuneiform (TATT). This restores muscle balance and prevents fixed recurrent deformity.

Question 467

Topic: 4. Pediatrics

A 2-year-old girl is referred for an anterolateral bowing of her tibia that recently fractured. Which of the following systemic conditions is most strongly associated with this pathology?

. Osteogenesis imperfecta
. Neurofibromatosis type 1
. Marfan syndrome
. Cleidocranial dysplasia
. Ehlers-Danlos syndrome

Correct Answer & Explanation

. Neurofibromatosis type 1

Explanation

Anterolateral bowing of the tibia that fractures and fails to heal is characteristic of congenital pseudarthrosis of the tibia (CPT). Over 50% of CPT cases are highly associated with Neurofibromatosis type 1 (NF1).

Question 468

Topic: 4. Pediatrics

An infant is evaluated for an intoeing gait. Examination reveals metatarsus adductus with a heel bisector line passing through the third web space. The deformity is actively correctable to the midline with tickling of the lateral foot. What is the most appropriate initial management?

. Immediate serial casting
. Surgical release of the abductor hallucis
. Prescription of reverse-last shoes
. Observation and parental reassurance
. Dennis-Brown bar application

Correct Answer & Explanation

. Observation and parental reassurance

Explanation

Flexible metatarsus adductus that actively corrects to midline (Bleck classification) resolves spontaneously in over 90% of cases. Observation and reassurance are the most appropriate management for this benign condition.

Question 469

Topic: Pediatric Lower Extremity

A 2-year-old boy presents with relapsed clubfoot after initial successful Ponseti casting. What is the most common cause of this recurrence?

. Failure to perform an Achilles tenotomy initially
. Non-compliance with the foot abduction orthosis
. Unrecognized underlying neuromuscular disorder
. Premature removal of the final cast
. Over-correction of the forefoot during casting

Correct Answer & Explanation

. Non-compliance with the foot abduction orthosis

Explanation

Non-compliance with the foot abduction brace is the most common cause of clubfoot relapse after successful Ponseti casting. Bracing is crucial up to age 4 to prevent recurrence.

Question 470

Topic: 4. Pediatrics

An infant with achondroplasia presents with central sleep apnea, hypotonia, and hyperreflexia. What is the most appropriate next step in management?

. Reassurance and observation
. Polysomnography and continuous positive airway pressure (CPAP)
. Cervical spine MRI to evaluate the craniocervical junction
. Surgical release of a tethered cord
. Thoracolumbar spine bracing

Correct Answer & Explanation

. Cervical spine MRI to evaluate the craniocervical junction

Explanation

These neurological findings suggest cervicomedullary compression at the foramen magnum, a life-threatening complication in infants with achondroplasia. An MRI of the craniocervical junction is essential for diagnosis before urgent decompression.

Question 471

Topic: Pediatric Lower Extremity
A 4-year-old boy with a relapsed clubfoot presents with dynamic forefoot supination during the swing phase of gait. His hindfoot remains plantigrade. Which of the following is the most appropriate surgical intervention?
. Repeat percutaneous Achilles tenotomy
. Full tibialis anterior tendon transfer to the lateral cuneiform
. Tibialis posterior tendon transfer through the interosseous membrane
. Split anterior tibial tendon transfer (SPLATT)
. Calcaneocuboid wedge osteotomy

Correct Answer & Explanation

. Full tibialis anterior tendon transfer to the lateral cuneiform

Explanation

Dynamic forefoot supination in a relapsed clubfoot with a flexible hindfoot is best treated with a full tibialis anterior tendon transfer to the lateral cuneiform. This converts the deforming supinating force into a corrective dorsiflexor.

Question 472

Topic: Pediatric Lower Extremity

According to the Ponseti method of clubfoot correction, what is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The mnemonic CAVE dictates the standard Ponseti sequence: Cavus, Adductus, Varus, and finally Equinus. The cavus is corrected first by supinating the forefoot and elevating the first ray to align it with the hindfoot.

Question 473

Topic: 4. Pediatrics

A newborn is diagnosed with congenital posteromedial bowing of the tibia. What is the expected long-term clinical outcome of this condition if left untreated?

. Progression to frank tibial pseudarthrosis
. Severe progressive valgus deformity of the knee
. Significant leg-length discrepancy requiring intervention
. Intractable ankle pain due to distal tibial wedging
. Complete spontaneous resolution with absolutely no residual deficits

Correct Answer & Explanation

. Significant leg-length discrepancy requiring intervention

Explanation

Congenital posteromedial bowing of the tibia typically resolves spontaneously regarding the angular deformity. However, patients inevitably develop a significant leg-length discrepancy requiring a shoe lift or eventual epiphysiodesis.

Question 474

Topic: 4. Pediatrics

An 8-year-old child with a known mutation in the COL2A1 gene is evaluated in the clinic. Which of the following ophthalmic complications must this patient be closely monitored for?

. Primary open-angle glaucoma
. Retinal detachment
. Congenital cataracts
. Macular degeneration
. Optic neuritis

Correct Answer & Explanation

. Retinal detachment

Explanation

Mutations in the COL2A1 gene cause Type II collagenopathies, such as Spondyloepiphyseal Dysplasia (SED). These patients are at a high risk for severe myopia and subsequent retinal detachment.

Question 475

Topic: Pediatric Hip

A 13-year-old girl with renal osteodystrophy undergoes surgical pinning for a severe left Slipped Capital Femoral Epiphysis (SCFE). What is the primary indication for prophylactic pinning of her contralateral asymptomatic hip?

. Her chronologic age over 12 years
. Her underlying endocrinopathy and metabolic disorder
. The severe grade of the left-sided slip
. Her female gender
. The presence of a metaphyseal blanch sign on the right

Correct Answer & Explanation

. Her underlying endocrinopathy and metabolic disorder

Explanation

Prophylactic pinning of the contralateral hip is highly indicated in patients with SCFE associated with endocrine or metabolic disorders (e.g., renal osteodystrophy, hypothyroidism). These conditions carry a near 100% risk of eventual bilateral involvement.

Question 476

Topic: 4. Pediatrics

An 18-month-old child with infantile Blount disease is evaluated. Which of the following radiographic parameters best differentiates this condition from physiologic bowing?

. Tibiofemoral angle greater than 10 degrees
. Metaphyseal-diaphyseal angle greater than 16 degrees
. Physeal-diaphyseal angle less than 10 degrees
. Medial cortical thickening of the proximal tibia
. Lateral wedging of the distal femoral epiphysis

Correct Answer & Explanation

. Metaphyseal-diaphyseal angle greater than 16 degrees

Explanation

The metaphyseal-diaphyseal angle (Drennan's angle) is crucial for differentiating infantile Blount disease from physiologic bowing. An angle greater than 16 degrees is highly predictive of progressive Blount disease requiring intervention.

Question 477

Topic: Pediatric Hip

A 6-month-old boy with Developmental Dysplasia of the Hip (DDH) has failed Pavlik harness treatment. A closed reduction and spica casting are planned. To minimize the risk of osteonecrosis of the femoral head, what defines the "safe zone" of positioning described by Ramsey?

. Between maximum adduction and the angle of re-dislocation
. Between maximum abduction and the angle of re-dislocation
. Between 90 degrees of flexion and maximum extension
. Between internal and external rotation limits
. Strict immobilization in the rigid Lorenz position

Correct Answer & Explanation

. Between maximum abduction and the angle of re-dislocation

Explanation

Ramsey's safe zone for DDH closed reduction is the arc between the angle of maximum abduction (which risks AVN if pushed too far) and the angle at which the hip redislocates in adduction. Spica casting should immobilize the hip within this safe arc.

Question 478

Topic: Pediatric Hip

In Legg-Calve-Perthes disease, the lateral pillar classification is used to determine prognosis. At what stage of the disease is this classification most accurately applied to guide treatment?

. Initial condensation stage
. Early fragmentation stage
. Late fragmentation stage
. Early reossification stage
. Healed stage

Correct Answer & Explanation

. Early fragmentation stage

Explanation

The lateral pillar (Herring) classification determines the retained height of the lateral pillar of the femoral head. It is most accurate and prognostically valuable when assessed during the early to late fragmentation phase of the disease.

Question 479

Topic: Pediatric Hip

A 14-year-old boy with a BMI of 35 presents with knee pain and is diagnosed with a unilateral slipped capital femoral epiphysis (SCFE). Which of the following best describes the anatomical direction of the epiphyseal slip relative to the femoral neck?

. Anterior and superior
. Posterior and inferior
. Posterior and superior
. Anterior and inferior
. Directly medial

Correct Answer & Explanation

. Posterior and inferior

Explanation

In SCFE, the femoral neck typically displaces anteriorly and superiorly. This means the epiphysis, which stays relatively reduced in the acetabulum, slips posteriorly and inferiorly relative to the femoral neck.

Question 480

Topic: 4. Pediatrics
Which rating best describes a child's hip affected with Perthes' disease that has healed with aspherical incongruity?
. Catterall 3
. Catterall 4
. Herring C
. Stulberg 4
. Stulberg 5

Correct Answer & Explanation

. Stulberg 4

Explanation

The Catterall and Herring classifications are used during the evolution of Perthes' disease to guide treatment; they are used during the fragmentation stage. It is impossible to know what the Catterall or Herring class was after healing has occurred. The Stulberg classification gives prognosis after healing. Stulberg 4 is aspherical but congruous. Stulberg 5 is aspherical and incongruous. Patients classified with Stulberg 5 hips typically have degenerative joint disease in early adulthood.

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