Menu

4. Pediatrics MCQs

Practice Set 219 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 4361

Topic: Pediatric Upper Extremity & Spine
What is the primary cause of cubitus varus deformity following closed reduction and percutaneous pinning of a Gartland type III supracondylar humerus fracture?
. Epiphyseal growth arrest of the lateral capitellum
. Inadequate correction of internal rotation and medial comminution
. Over-tightening of the lateral entry pin
. Iatrogenic ulnar nerve entrapment
. Avascular necrosis of the trochlea

Correct Answer & Explanation

. Inadequate correction of internal rotation and medial comminution

Explanation

Cubitus varus after supracondylar humerus fractures is primarily a cosmetic deformity resulting from malunion. It specifically occurs due to the failure to adequately reduce internal rotation and correct coronal tilt in the presence of medial column comminution.

Question 4362

Topic: Pediatric Hip

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 3-week follow-up, she exhibits decreased active extension of the knee on the affected side but cries when the leg is manipulated. What is the most likely cause of this clinical finding?

. Femoral nerve palsy
. Sciatic nerve palsy
. Obturator nerve palsy
. Avascular necrosis of the femoral head
. Missed patellar dislocation

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, typically resulting from excessive hyperflexion of the hip. Treatment involves adjusting the anterior straps to decrease hip flexion, which usually leads to spontaneous resolution of the palsy.

Question 4363

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy presents with a displaced Gartland type III supracondylar humerus fracture. After closed reduction and percutaneous pinning, the hand is pink, warm, and has a capillary refill of 2 seconds, but the radial pulse remains absent on Doppler ultrasound. What is the most appropriate next step in management?
. Immediate open vascular exploration
. Observation and admission for 24-48 hours
. Administration of intravenous heparin
. Removal of the pins and open reduction
. Emergent volar fasciotomy

Correct Answer & Explanation

. Observation and admission for 24-48 hours

Explanation

A 'pulseless, pink' hand following successful reduction and pinning of a supracondylar fracture indicates adequate collateral perfusion. Observation is the standard of care, as the pulse typically returns over hours to days without the need for acute vascular exploration.

Question 4364

Topic: Pediatric Hip

An 8-year-old boy presents with a progressive limp and hip pain. Radiographs demonstrate sclerosis and fragmentation of the proximal femoral epiphysis consistent with Legg-Calve-Perthes disease. Which of the following radiographic findings in the lateral pillar classification is most predictive of a poor long-term outcome?

. More than 50% loss of lateral pillar height
. Involvement of the medial pillar only
. A subchondral radiolucent line (Crescent sign)
. Metaphyseal cysts
. A V-shaped radiolucency in the lateral epiphysis (Gage sign)

Correct Answer & Explanation

. More than 50% loss of lateral pillar height

Explanation

The Lateral Pillar (Herring) classification is highly prognostic in Legg-Calve-Perthes disease. Group C, defined as greater than 50% collapse of the lateral pillar, is associated with the worst outcomes, often leading to early osteoarthritis, particularly in children over 8 years old.

Question 4365

Topic: Pediatric Hip

An 11-year-old girl with end-stage renal disease and renal osteodystrophy undergoes in situ percutaneous pinning for a left slipped capital femoral epiphysis (SCFE). Her right hip is completely asymptomatic and radiographically normal. What is the most appropriate management for the right hip?

. Observation with serial radiographs every 6 months
. Prophylactic in situ percutaneous pinning
. Prophylactic spica cast application
. Core decompression of the femoral neck
. Physeal bar resection

Correct Answer & Explanation

. Prophylactic in situ percutaneous pinning

Explanation

Patients with endocrinopathies, such as renal osteodystrophy or hypothyroidism, have an exceptionally high risk of developing bilateral SCFE. Prophylactic pinning of the contralateral asymptomatic hip is strongly recommended in these specific patient populations.

Question 4366

Topic: 4. Pediatrics

A newborn is evaluated for a congenital right lower extremity deformity. Clinical examination reveals an anteromedial tibial bow, a deep skin dimple over the anterior tibia, an absent lateral ray of the foot, and significant limb length discrepancy. What is the most likely diagnosis?

. Congenital pseudarthrosis of the tibia
. Tibial hemimelia
. Proximal focal femoral deficiency
. Fibular hemimelia
. Amniotic band syndrome

Correct Answer & Explanation

. Fibular hemimelia

Explanation

Fibular hemimelia classically presents with an anteromedial tibial bow, skin dimpling over the anterior tibia, absent lateral foot rays, and limb length discrepancy. It is the most common congenital longitudinal deficiency of the long bones.

Question 4367

Topic: 4. Pediatrics

A 3-year-old child presents with progressive bilateral genu varum. Radiographs demonstrate a prominent medial metaphyseal beak of the proximal tibia with a metaphyseal-diaphyseal angle (Drennan's angle) of 20 degrees. What is the most appropriate initial management?

. Reassurance and clinical observation
. Knee-ankle-foot orthoses (KAFOs)
. Proximal tibial valgus osteotomy
. Guided growth using tension band plates laterally
. Epiphyseodesis of the lateral proximal tibia

Correct Answer & Explanation

. Knee-ankle-foot orthoses (KAFOs)

Explanation

A metaphyseal-diaphyseal angle greater than 16 degrees indicates a high risk for infantile Blount's disease. In a child under 4 years of age with Langenskiold stage I or II, bracing with KAFOs is the initial treatment of choice to unload the medial compartment.

Question 4368

Topic: 4. Pediatrics
A 14-year-old girl sustains an ankle injury while playing soccer. Radiographs reveal a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. What is the primary mechanism causing this specific fracture pattern?
. Avulsion by the anterior inferior tibiofibular ligament (AITFL) due to external rotation
. Compression from the talus during severe axial loading
. Avulsion by the calcaneofibular ligament during forced inversion
. Posterior displacement causing pull by the posterior inferior tibiofibular ligament
. Direct traumatic impact to the anterolateral ankle mortise

Correct Answer & Explanation

. Avulsion by the anterior inferior tibiofibular ligament (AITFL) due to external rotation

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It occurs because the distal tibial physis closes from medial to lateral, leaving the anterolateral portion vulnerable to avulsion by the AITFL during external rotation forces.

Question 4369

Topic: 4. Pediatrics

A 2-month-old infant boy presents with his head tilted to the right and chin rotated to the left. A firm, painless, non-pulsatile mass is palpable in the right side of the neck. Ultrasound confirms a fibrotic mass within the sternocleidomastoid muscle. What is the most common associated musculoskeletal condition that must be screened for in this patient?

. Sprengel deformity
. Developmental dysplasia of the hip (DDH)
. Metatarsus adductus
. Congenital scoliosis
. Klippel-Feil syndrome

Correct Answer & Explanation

. Developmental dysplasia of the hip (DDH)

Explanation

Congenital muscular torticollis has a well-documented association with developmental dysplasia of the hip (DDH), with incidence rates reported up to 20%. Therefore, all infants presenting with congenital muscular torticollis should undergo rigorous screening for DDH via clinical exam and ultrasound.

Question 4370

Topic: Pediatric Upper Extremity & Spine

A 12-year-old elite baseball pitcher presents with medial elbow pain that worsens during the acceleration phase of throwing. Radiographs demonstrate widening of the medial epicondyle apophysis. Which muscle group is the primary deforming force contributing to this condition?

. Extensor carpi radialis brevis and longus
. Triceps brachii and anconeus
. Biceps brachii and brachialis
. Flexor-pronator mass
. Brachioradialis and supinator

Correct Answer & Explanation

. Flexor-pronator mass

Explanation

'Little League Elbow' is a traction apophysitis of the medial epicondyle caused by repetitive valgus overload during throwing. The primary deforming forces pulling on the medial epicondyle apophysis are the flexor-pronator mass and the ulnar collateral ligament.

Question 4371

Topic: 4. Pediatrics

An 18-year-old male presents to the emergency department after a football tackle complaining of severe pain at the base of his neck. He is experiencing mild stridor and a choking sensation. Clinical exam and CT imaging reveal a posterior displacement of the medial clavicle. Given the patient's age and clinical presentation, what is the most accurate anatomic description of this injury?

. A complete rupture of the anterior and posterior sternoclavicular ligaments
. A physeal fracture of the medial clavicle with posterior displacement of the metaphysis
. A pure subluxation of the intra-articular disc of the sternoclavicular joint
. A transverse fracture through the manubrium sterni
. A bipolar dislocation of the clavicle (floating clavicle)

Correct Answer & Explanation

. A physeal fracture of the medial clavicle with posterior displacement of the metaphysis

Explanation

The medial clavicular epiphysis is the last physis in the body to fuse, typically closing between 22 and 25 years of age. Therefore, what appears clinically and radiographically as a 'sternoclavicular joint dislocation' in a patient under age 22 is almost always a Salter-Harris type I or II physeal fracture of the medial clavicle, with the epiphysis remaining in the sternoclavicular joint.

Question 4372

Topic: 4. Pediatrics

A 13-year-old elite Little League pitcher presents with progressive, activity-related right proximal humerus pain over the past 6 weeks. He denies any acute trauma. Plain radiographs reveal widening and irregularity of the proximal humeral physis compared to the contralateral side. What is the most appropriate initial management?

. In situ percutaneous pinning of the physis
. Arthroscopic evaluation for a superior labrum anterior-posterior (SLAP) tear
. 3 weeks of sling immobilization followed by an immediate return to a progressive throwing program
. Complete cessation of throwing for 3 months with a focus on core and lower extremity strengthening
. Corticosteroid injection into the subacromial space followed by physical therapy

Correct Answer & Explanation

. Complete cessation of throwing for 3 months with a focus on core and lower extremity strengthening

Explanation

The diagnosis is 'Little League Shoulder', which is an overuse injury resulting in a stress fracture of the proximal humeral physis (Salter-Harris type I). The standard of care is complete cessation of throwing for approximately 3 months (until radiographic and clinical resolution). Physical therapy should focus on core, periscapular, and lower extremity strengthening to correct kinetic chain deficits before initiating a structured return-to-throwing program.

Question 4373

Topic: 4. Pediatrics

A 13-year-old male baseball pitcher complains of right shoulder pain that worsens when throwing hard. He has localized tenderness over the lateral aspect of the proximal humerus. Radiographs reveal widening of the proximal humeral physis compared to the contralateral side.

What is the recommended initial management for this condition?

. Immediate surgical pinning of the physis
. Complete cessation of throwing for 3 months followed by a gradual return-to-throwing program
. Corticosteroid injection into the subacromial space
. Sling immobilization for 6 weeks followed by operative stabilization if pain persists
. Continuation of throwing but strictly avoiding breaking pitches (e.g., curveballs)

Correct Answer & Explanation

. Complete cessation of throwing for 3 months followed by a gradual return-to-throwing program

Explanation

This clinical picture describes 'Little League Shoulder', which is a proximal humeral epiphysiolysis (a stress fracture through the physis, Salter-Harris Type I) caused by repetitive rotational torque during the throwing motion. The gold standard treatment is absolute rest from throwing, typically for a minimum of 3 months, until clinical symptoms resolve and radiographs demonstrate physeal healing. Surgery is almost never indicated.

Question 4374

Topic: 4. Pediatrics

A 5-year-old child presents with short-limbed dwarfism, frontal bossing, and a trident hand. Radiographs show a narrowing of the interpedicular distances in the lumbar spine. What is the genetic basis of this skeletal dysplasia?

. Mutation in COL1A1 gene
. Mutation in COMP gene
. Gain-of-function mutation in FGFR3 gene
. Loss-of-function mutation in RUNX2 gene
. Mutation in the diastrophic dysplasia sulfate transporter (SLC26A2) gene

Correct Answer & Explanation

. Gain-of-function mutation in FGFR3 gene

Explanation

Achondroplasia is caused by a gain-of-function mutation in the FGFR3 gene, which inhibits chondrocyte proliferation in the proliferative zone of the physis.

Question 4375

Topic: 4. Pediatrics

A newborn is diagnosed with Osteogenesis Imperfecta type II. This condition is typically lethal in the perinatal period. What is the fundamental molecular defect associated with this disease?

. Defective mineralization of osteoid
. Abnormal cross-linking of type II collagen
. Substitution of glycine in the triple helix of type I collagen
. Impaired osteoclast function and ruffled border formation
. Defect in the maturation of hypertrophic chondrocytes

Correct Answer & Explanation

. Substitution of glycine in the triple helix of type I collagen

Explanation

Osteogenesis imperfecta is most commonly caused by mutations in COL1A1 or COL1A2, often involving a substitution of glycine with a bulkier amino acid, severely disrupting the type I collagen triple helix.

Question 4376

Topic: 4. Pediatrics

A 10-year-old boy presents with a waddling gait, joint pain, and stiffness. Radiographs show delayed and irregular ossification of the capital femoral epiphyses, but normal spine radiographs. A 'double-layer' patella is noted on lateral knee X-rays. Which gene is most commonly mutated?

. COMP
. COL2A1
. FGFR3
. GNAS
. SOX9

Correct Answer & Explanation

. COMP

Explanation

Multiple Epiphyseal Dysplasia (MED) most commonly results from a mutation in the Cartilage Oligomeric Matrix Protein (COMP) gene. A double-layer patella is a classic radiographic sign.

Question 4377

Topic: 4. Pediatrics

A neonate is born with extremely short limbs, severe clubfeet, a 'hitchhiker' thumb, and cystic swelling of the ear pinnae (cauliflower ears). Radiographs show short, thick tubular bones. What is the underlying genetic defect?

. FGFR3 mutation impairing chondrocyte proliferation
. SLC26A2 mutation causing impaired sulfate transport
. COMP mutation causing retained cartilage matrix
. COL2A1 mutation affecting Type II collagen
. COL1A1 mutation affecting Type I collagen

Correct Answer & Explanation

. SLC26A2 mutation causing impaired sulfate transport

Explanation

The clinical presentation is classic for Diastrophic Dysplasia. It is an autosomal recessive disorder caused by mutations in the SLC26A2 gene, which encodes a sulfate transporter, leading to undersulfated proteoglycans in cartilage.

Question 4378

Topic: 4. Pediatrics

A 6-year-old boy presents with a waddling gait and bilateral knee pain. Radiographs reveal delayed and irregular ossification of multiple epiphyses and a characteristic 'double-layered' patella. A mutation in the gene encoding which protein is most commonly responsible?

. Cartilage oligomeric matrix protein (COMP)
. Fibroblast growth factor receptor 3 (FGFR3)
. Type I collagen (COL1A1)
. Core-binding factor alpha 1 (CBFA1/RUNX2)
. Lysosomal alpha-L-iduronidase

Correct Answer & Explanation

. Cartilage oligomeric matrix protein (COMP)

Explanation

Multiple Epiphyseal Dysplasia (MED) commonly presents with joint pain, waddling gait, and a double-layered patella on lateral radiographs. The most common genetic mutation is in the COMP gene (Cartilage Oligomeric Matrix Protein).

Question 4379

Topic: 4. Pediatrics

A 4-year-old boy presents with disproportionate short stature, frontal bossing, and rhizomelic shortening of the limbs. Radiographs reveal narrowing of the interpedicular distances in the lumbar spine. What is the underlying genetic mechanism for this condition?

. COL1A1 mutation
. COMP mutation
. FGFR3 inactivating mutation
. FGFR3 activating mutation
. CBFA1 mutation

Correct Answer & Explanation

. FGFR3 activating mutation

Explanation

Achondroplasia is caused by a gain-of-function (activating) mutation in the FGFR3 gene. This overactivity inhibits chondrocyte proliferation in the proliferative zone of the physis, leading to diminished endochondral ossification.

Question 4380

Topic: 4. Pediatrics

A 2-year-old girl is evaluated for multiple low-energy long bone fractures. Physical examination reveals blue sclerae and mild joint hyperlaxity. Which of the following describes the most likely underlying pathophysiological defect?

. Defect in Type II collagen
. Defect in Type I collagen synthesis
. Osteoclast dysfunction
. FGFR3 mutation
. Defective mineralization of osteoid

Correct Answer & Explanation

. Defect in Type I collagen synthesis

Explanation

The patient has Osteogenesis Imperfecta (OI), characterized by blue sclerae and recurrent fractures. OI is primarily caused by mutations in COL1A1 or COL1A2, resulting in quantitative or qualitative defects in Type I collagen.

Test Yourself

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

On this Page