Menu

4. Pediatrics MCQs

Practice Set 28 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 541

Topic: Pediatric Upper Extremity & Spine
A 6-year-old child sustains a Gartland type III extension-type supracondylar humerus fracture. On physical examination, the child is unable to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. Which nerve is most likely injured?
. Radial nerve
. Ulnar nerve
. Anterior interosseous nerve
. Posterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. Injury presents with an inability to form the "OK" sign due to weakness of the flexor pollicis longus and the flexor digitorum profundus to the index finger.

Question 542

Topic: Pediatric Lower Extremity

An orthopedic surgeon is utilizing the Ponseti method to correct an idiopathic clubfoot in a 2-week-old infant. According to this protocol, which component of the deformity must be corrected last?

. Cavus
. Adductus
. Varus
. Equinus
. Supination

Correct Answer & Explanation

. Equinus

Explanation

In the Ponseti method, the components of the clubfoot deformity are corrected in a specific sequence summarized by the acronym CAVE: Cavus, Adductus, Varus, and finally Equinus. Equinus is typically corrected last, often requiring a percutaneous Achilles tenotomy.

Question 543

Topic: Pediatric Hip

A 13-year-old obese boy presents with a 3-week history of vaguely localized knee pain and a limp. Examination reveals obligatory external rotation of the hip during passive hip flexion. What is the most appropriate initial management?

. Open reduction and internal fixation
. Closed reduction and internal fixation
. In situ single screw fixation
. Spica cast application
. Proximal femoral osteotomy

Correct Answer & Explanation

. In situ single screw fixation

Explanation

The presentation is classic for a slipped capital femoral epiphysis (SCFE), characterized by obligatory external rotation with hip flexion. The gold standard initial treatment for a stable SCFE is in situ fixation with a single cannulated screw.

Question 544

Topic: Pediatric Hip
A 6-year-old boy with a painless limp is diagnosed with Legg-Calvé-Perthes disease. Radiographs show fragmentation of the femoral head. According to the Herring lateral pillar classification, a Group C classification is defined by what degree of lateral pillar height loss?
. No height loss
. <25% height loss
. 25-50% height loss
. >50% height loss
. Complete head collapse

Correct Answer & Explanation

. >50% height loss

Explanation

The Herring lateral pillar classification determines prognosis in Legg-Calvé-Perthes disease based on the height of the lateral pillar during the fragmentation stage. Group C indicates greater than 50% loss of lateral pillar height and carries the poorest prognosis.

Question 545

Topic: Pediatric Hip

A 3-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During follow-up, the parents note the infant is no longer actively extending the knee on the affected side. What is the most appropriate next step in management?

. Continue the harness and observe
. Adjust the anterior straps to increase flexion
. Remove the harness and allow temporary rest
. Switch to a rigid abduction brace immediately
. Perform closed reduction and spica casting

Correct Answer & Explanation

. Remove the harness and allow temporary rest

Explanation

Decreased active knee extension in a Pavlik harness indicates a femoral nerve palsy, typically caused by hyperflexion. The correct management is immediate removal of the harness to allow for nerve recovery before reassessing treatment options.

Question 546

Topic: 4. Pediatrics

A 7-year-old child with Gross Motor Function Classification System (GMFCS) Level V cerebral palsy is being evaluated. Which of the following radiographic parameters is most critical for routine screening to assess the risk of hip subluxation and dislocation in this patient?

. Alpha angle
. Wiberg center-edge angle
. Reimers migration percentage
. Tonnis angle
. Neck-shaft angle

Correct Answer & Explanation

. Reimers migration percentage

Explanation

Children with severe cerebral palsy (GMFCS levels IV and V) have a high risk of progressive spastic hip displacement. The Reimers migration percentage on an AP pelvis radiograph is the standard screening metric, with values >30% typically warranting surgical consideration.

Question 547

Topic: 4. Pediatrics
A 4-year-old girl with blue sclerae, dentinogenesis imperfecta, and multiple prior fractures is diagnosed with Osteogenesis Imperfecta. This condition is primarily caused by an inherited defect in the synthesis of which of the following?
. Type I collagen
. Type II collagen
. Type III collagen
. Type IV collagen
. Type V collagen

Correct Answer & Explanation

. Type I collagen

Explanation

Osteogenesis Imperfecta (OI) is a genetic disorder of connective tissue caused primarily by mutations in the COL1A1 or COL1A2 genes, which encode the chains of Type I collagen. This leads to bone fragility, blue sclerae, and hearing loss.

Question 548

Topic: 4. Pediatrics

A newborn is noted to have rhizomelic short stature, frontal bossing, and midface hypoplasia. Radiographs reveal narrowing of the interpedicular distances in the lumbar spine. Which genetic mutation is responsible for this condition?

. COMP
. COL2A1
. FGFR3
. SOX9
. RUNX2

Correct Answer & Explanation

. FGFR3

Explanation

Achondroplasia is the most common form of skeletal dysplasia and disproportionate short stature. It is caused by an autosomal dominant, gain-of-function mutation in the Fibroblast Growth Factor Receptor 3 (FGFR3) gene, which inhibits chondrocyte proliferation at the growth plate.

Question 549

Topic: 4. Pediatrics
A 4-year-old child presents with progressive genu varum. Radiographs demonstrate focal depression and a bony beak at the medial metaphysis of the proximal tibia, consistent with Langenskiöld stage III Blount disease. What is the primary pathoanatomic location of the growth disturbance?
. Medial proximal tibial physis
. Lateral proximal tibial physis
. Medial distal femoral physis
. Lateral distal femoral physis
. Proximal fibular physis

Correct Answer & Explanation

. Medial proximal tibial physis

Explanation

Blount disease (tibia vara) is a developmental disorder characterized by abnormal endochondral ossification and growth suppression at the medial proximal tibial physis. This results in progressive varus, internal rotation, and procurvatum deformities of the tibia.

Question 550

Topic: Pediatric Upper Extremity & Spine

A 12-year-old girl is evaluated for Adolescent Idiopathic Scoliosis (AIS). She has not yet reached menarche. Radiographs show a right thoracic curve of 35 degrees. Her Risser stage is 1. What is the most appropriate recommendation regarding treatment?

. Observation with repeated radiographs in 6 months
. Initiation of full-time TLSO bracing
. Immediate posterior spinal fusion
. Nighttime bending brace only
. Physical therapy for curve correction

Correct Answer & Explanation

. Initiation of full-time TLSO bracing

Explanation

Indications for bracing in AIS include a curve between 25 and 45 degrees in a patient with significant remaining growth (typically Risser 0-2 and pre-menarchal). A full-time TLSO brace is recommended to prevent further progression in this high-risk scenario.

Question 551

Topic: 4. Pediatrics

A 10-year-old girl is diagnosed with a polyostotic bone lesion demonstrating a "ground-glass" appearance. This condition is most commonly associated with a somatic activating mutation in which of the following?

. GNAS1
. EXT1
. NF1
. FGFR3
. COMP

Correct Answer & Explanation

. GNAS1

Explanation

Fibrous dysplasia is caused by a somatic activating mutation in the GNAS1 gene, resulting in increased intracellular cAMP. This leads to abnormal differentiation of osteoblasts and replacement of normal medullary bone with fibrous tissue.

Question 552

Topic: 4. Pediatrics

A 7-year-old boy has short stature, unilateral coxa vara, and lack of ossification in the medial pubic rami. The most likely diagnosis is:

. Achondroplasia
. Diastrophic dysplasia
. Osteogenesis imperfecta
. C leidocranial dysplasia
. Multiple epiphyseal dysplasia

Correct Answer & Explanation

. C leidocranial dysplasia

Explanation

Cleidocranial dysplasia produces the above findings, in addition to partial or complete lack of formation of the clavicles and persistent widening of the cranial fontanelles. None of these findings are present in the other conditions.

Question 553

Topic: 4. Pediatrics

Polyostotic fibrous dysplasia is caused by a mutation in which of the following genes:

. GNAS 1
. EXT 1
. Fibroblast growth factor receptor protein
. CFBA1
. COL1A1

Correct Answer & Explanation

. GNAS 1

Explanation

Fibrous dysplasia is due to a postzygotic mutation in the GNAS1 gene. By contrast, EXT 1 mutations can cause multiple exostoses, and fibroblast growth factor receptor protein mutations cause achondroplasia, among other disorders. C FBA1 mutations are responsible for cleidocranial dysplasia. C OL1A1 mutations are responsible for osteogenesis imperfecta.

Question 554

Topic: Pediatric Hip

A 12-year-old obese boy presents with right thigh pain and a limp for 3 weeks. Examination reveals obligatory external rotation of the right hip during passive flexion. Radiographs demonstrate a 'slip' of the capital femoral epiphysis. What is the most appropriate initial treatment?

. Closed reduction and spica casting
. In situ single screw fixation
. Capital realignment osteotomy
. Slipped capital femoral epiphysis pinning with two screws
. Observation and protected weight bearing

Correct Answer & Explanation

. In situ single screw fixation

Explanation

The patient has a stable slipped capital femoral epiphysis (SCFE). The standard of care is in situ fixation with a single cannulated screw placed in the center of the epiphysis.

Question 555

Topic: Pediatric Hip

A 3-month-old girl is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up visit, the parents report she has stopped kicking her left leg, and you note an absence of active knee extension. What is the most appropriate next step in management?

. Switch to a rigid hip abduction orthosis
. Adjust the anterior straps to increase hip flexion
. Remove the harness and allow a period of rest
. Perform an urgent ultrasound of the hip
. Reassure the parents and continue the current harness settings

Correct Answer & Explanation

. Remove the harness and allow a period of rest

Explanation

Decreased active knee extension in a Pavlik harness indicates a femoral nerve palsy caused by hyperflexion of the hip. The harness must be removed or adjusted immediately to allow recovery of nerve function.

Question 556

Topic: Pediatric Lower Extremity

In the Ponseti method for treating idiopathic clubfoot, which of the following represents the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Varus, Adductus, Equinus

Explanation

The sequence of correction in the Ponseti method follows the acronym CAVE: Cavus, Adductus, Varus, and finally Equinus.

Question 557

Topic: 4. Pediatrics

A 4-year-old child presents with worsening bilateral bowing of the legs. Radiographs reveal a sharp metaphyseal beak and a metaphyseal-diaphyseal angle of 18 degrees. What is the most likely diagnosis?

. Physiologic genu varum
. Achondroplasia
. Rickets
. Infantile Blount disease
. Osteogenesis imperfecta

Correct Answer & Explanation

. Infantile Blount disease

Explanation

A metaphyseal-diaphyseal angle greater than 16 degrees in a child with tibial bowing strongly suggests infantile Blount disease rather than physiologic genu varum.

Question 558

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a supracondylar humerus fracture that is displaced posterolaterally. Which nerve is at the highest risk of injury in this specific displacement pattern?

. Radial nerve
. Anterior interosseous nerve (AIN)
. Ulnar nerve
. Posterior interosseous nerve (PIN)
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve (AIN)

Explanation

Posterolaterally displaced supracondylar humerus fractures stretch the medial structures, putting the anterior interosseous nerve (AIN) and brachial artery at highest risk.

Question 559

Topic: 4. Pediatrics

A newborn presents with multiple fractures and blue sclerae. Genetic testing confirms Osteogenesis Imperfecta (OI). This condition is primarily caused by a mutation affecting which of the following?

. Type II collagen
. Type I collagen
. Fibroblast growth factor receptor 3 (FGFR3)
. Cartilage oligomeric matrix protein (COMP)
. Fibrillin-1

Correct Answer & Explanation

. Type I collagen

Explanation

Osteogenesis Imperfecta is typically caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, which encode for Type I collagen.

Question 560

Topic: 4. Pediatrics
A 14-year-old boy sustains an inversion ankle injury. Radiographs show a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. The avulsed fragment is attached to which of the following ligaments?
. Anterior talofibular ligament
. Calcaneofibular ligament
. Anterior inferior tibiofibular ligament (AITFL)
. Deltoid ligament
. Posterior inferior tibiofibular ligament (PITFL)

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament (AITFL)

Explanation

This describes a juvenile Tillaux fracture. The fracture occurs due to an avulsion by the anterior inferior tibiofibular ligament (AITFL) as the medial physis closes before the lateral physis.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page