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4. Pediatrics MCQs

Practice Set 239 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 4761

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains a Gartland type III extension-type supracondylar humerus fracture. Following prompt closed reduction and percutaneous pinning, the hand remains pink and warm, but the radial pulse is absent. Capillary refill is less than 2 seconds. What is the most appropriate next step in management?
. Immediate exploration of the brachial artery
. CT angiography of the upper extremity
. Observation and hospital admission
. Removal of the pins and open reduction

Correct Answer & Explanation

. Observation and hospital admission

Explanation

A 'pink, pulseless' hand following reduction of a supracondylar fracture indicates adequate collateral perfusion. Observation is the standard of care, as the pulse often returns within a few days.

Question 4762

Topic: 4. Pediatrics

A 2-year-old child presents with severe bilateral leg bowing. Radiographs demonstrate a metaphyseal-diaphyseal angle (Drennan angle) of 18 degrees with medial metaphyseal beaking.

What is the initial treatment of choice?

. Observation with yearly radiographs
. Knee-ankle-foot orthoses (KAFOs)
. Proximal tibial valgus osteotomy
. Eight-plate guided growth of the medial proximal tibia

Correct Answer & Explanation

. Observation with yearly radiographs

Explanation

A metaphyseal-diaphyseal angle greater than 16 degrees suggests infantile Blount disease rather than physiologic bowing. In a child under 3 years of age with early-stage disease, KAFO bracing during weight-bearing is the first-line treatment.

Question 4763

Topic: Pediatric Hip

A 4-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, the parents note the child is no longer actively kicking the knee into extension on the affected side. What is the most likely cause of this complication?

. Avascular necrosis of the femoral head
. Sciatic nerve palsy from excessive abduction
. Femoral nerve palsy from excessive hip flexion
. Obturator nerve stretch injury

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Femoral nerve palsy in a Pavlik harness is caused by hyperflexion of the hip. Management involves adjusting the anterior strap to reduce flexion or temporarily discontinuing the harness until function returns.

Question 4764

Topic: 4. Pediatrics

A 7-year-old girl with spastic quadriplegic cerebral palsy (GMFCS Level V) presents with a progressively painful left hip. Radiographs show a Reimers Migration Percentage of 65% with breaking of the Shenton line, but no degenerative changes. What is the recommended surgical management?

. Adductor and iliopsoas tenotomies alone
. Varus derotational osteotomy (VDRO) of the proximal femur with pelvic osteotomy
. Total hip arthroplasty
. Proximal femoral resection (Castle procedure)

Correct Answer & Explanation

. Adductor and iliopsoas tenotomies alone

Explanation

For a subluxated hip (Migration Percentage >50%) in a CP patient with reconstructable articular cartilage, a proximal femoral VDRO combined with a volume-reducing pelvic osteotomy (e.g., Dega or San Diego) is the gold standard to achieve a stable, concentric hip.

Question 4765

Topic: Pediatric Hip

When evaluating a patient with Legg-Calve-Perthes (LCP) disease, several demographic and radiographic factors guide prognosis. Which of the following is associated with a POOR clinical outcome?

. Age of onset at 4 years
. Male gender
. Female gender
. Herring Lateral Pillar Group A classification

Correct Answer & Explanation

. Age of onset at 4 years

Explanation

Female patients with LCP disease generally have a worse prognosis than age-matched males because they reach skeletal maturity earlier, allowing less time for the femoral head to remodel.

Question 4766

Topic: Pediatric Hip

According to the Loder classification, which clinical finding strictly defines a slipped capital femoral epiphysis (SCFE) as 'unstable'?

. Slip angle greater than 50 degrees
. Presence of an effusion on ultrasound
. Inability to ambulate with or without crutches
. Duration of symptoms less than 3 weeks

Correct Answer & Explanation

. Slip angle greater than 50 degrees

Explanation

The Loder classification defines a SCFE as unstable if the patient is unable to ambulate even with crutches. Unstable slips carry a significantly higher risk of avascular necrosis (up to 47%).

Question 4767

Topic: 4. Pediatrics

A 3-year-old boy presents with a history of recurrent low-energy fractures, blue sclerae, and dentinogenesis imperfecta. Genetic testing is most likely to reveal a mutation affecting the synthesis of which structural protein?

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

Correct Answer & Explanation

. Type I collagen

Explanation

The patient's presentation is classic for Osteogenesis Imperfecta (OI), which is primarily caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, leading to defective Type I collagen synthesis.

Question 4768

Topic: 4. Pediatrics

A newborn is noted to have anterolateral bowing of the tibia. Over the first year of life, the tibia fractures and fails to heal, progressing to a congenital pseudarthrosis of the tibia (CPT). This condition is most strongly associated with which underlying disorder?

. Osteogenesis Imperfecta
. Achondroplasia
. Neurofibromatosis type 1
. Cleidocranial dysplasia

Correct Answer & Explanation

. Osteogenesis Imperfecta

Explanation

Congenital pseudarthrosis of the tibia with anterolateral bowing is highly associated with Neurofibromatosis type 1 (NF1), which is present in approximately 50% of these patients.

Question 4769

Topic: Pediatric Lower Extremity

An infant is brought to the clinic with bilateral idiopathic clubfoot. The treating orthopedist decides to initiate serial casting using the Ponseti method. What is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method follows the CAVE sequence: Cavus, Adductus, Varus, and Equinus. The cavus is corrected first by supinating the forefoot to align it with the hindfoot, followed by correcting adductus and varus simultaneously, and finally equinus is addressed, often requiring an Achilles tenotomy.

Question 4770

Topic: Pediatric Hip

A 13-year-old boy undergoes an urgent in situ pinning for an unstable slipped capital femoral epiphysis (SCFE) of the right hip.

Which of the following complications is he at the highest risk for developing compared to a patient with a stable SCFE?

. Chondrolysis
. Avascular necrosis
. Femoroacetabular impingement
. Slip progression
. Infection

Correct Answer & Explanation

. Chondrolysis

Explanation

Unstable SCFE is defined by the inability to bear weight and is associated with a significantly higher risk of avascular necrosis (AVN), up to 50%, compared to almost 0% in stable SCFE. Urgent decompression and pinning are required to mitigate this risk.

Question 4771

Topic: Pediatric Hip

A 10-week-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her follow-up appointment, the mother notes that the child is no longer kicking her right leg actively. On examination, there is decreased spontaneous active knee extension on the right. What is the most likely cause?

. Excessive hip flexion in the harness
. Excessive hip abduction in the harness
. Septic arthritis of the hip
. Avascular necrosis of the femoral head
. Excessive hip adduction in the harness

Correct Answer & Explanation

. Excessive hip flexion in the harness

Explanation

Decreased active knee extension indicates a femoral nerve palsy, a known complication of the Pavlik harness caused by excessive hip flexion. If this occurs, the harness is typically removed or adjusted to reduce flexion until nerve function recovers.

Question 4772

Topic: Pediatric Hip

In evaluating a child with Legg-Calve-Perthes disease (LCPD),

which of the following is considered the single most significant prognostic factor for the final outcome of the hip?

. Gender of the patient
. Duration of symptoms prior to diagnosis
. Age of the patient at the onset of the disease
. Degree of initial hip pain
. Presence of a limp

Correct Answer & Explanation

. Gender of the patient

Explanation

Age at disease onset is the most critical prognostic factor in LCPD. Children diagnosed before the age of 6 to 8 years have significantly better remodeling potential and superior long-term clinical outcomes compared to older children.

Question 4773

Topic: 4. Pediatrics

A 3-year-old obese girl presents with progressive bowing of her left leg and a lateral thrust during gait. Radiographs reveal an increased metaphyseal-diaphyseal angle.

Which of the following is true regarding the initial management of infantile Blount's disease?

. It is characterized by lateral collateral ligament laxity
. Observation is recommended until age 5
. Bracing is most effective in unilateral disease in children under age 3
. It most commonly involves the distal femur
. Guided growth is contraindicated

Correct Answer & Explanation

. It is characterized by lateral collateral ligament laxity

Explanation

Infantile Blount's disease is an osteochondrosis of the medial proximal tibial physis. KAFO bracing is most effective when initiated before age 3, particularly in patients with unilateral disease.

Question 4774

Topic: 4. Pediatrics

A 6-year-old boy with spastic quadriplegic cerebral palsy is undergoing routine hip surveillance. His Gross Motor Function Classification System (GMFCS) level is V. What is the most widely accepted radiographic measurement used to monitor for hip displacement in this patient?

. Center-edge angle of Wiberg
. Alpha angle of Graf
. Reimers migration percentage
. Tonnis angle
. Acetabular index

Correct Answer & Explanation

. Center-edge angle of Wiberg

Explanation

Reimers migration percentage is the standard radiographic measurement used in cerebral palsy hip surveillance to quantify lateral displacement of the femoral head. A migration index greater than 30% typically prompts closer observation or surgical intervention.

Question 4775

Topic: 4. Pediatrics

An 18-month-old child is diagnosed with congenital pseudarthrosis of the tibia (CPT) showing classic anterolateral bowing. This condition is most strongly associated with which of the following systemic disorders?

. Osteogenesis Imperfecta
. Achondroplasia
. Neurofibromatosis type 1
. Marfan syndrome
. Ehlers-Danlos syndrome

Correct Answer & Explanation

. Osteogenesis Imperfecta

Explanation

Congenital pseudarthrosis of the tibia (CPT) presents with anterolateral bowing and has a very strong association with Neurofibromatosis type 1 (NF1). Over 50% of patients with CPT have a diagnosis of NF1.

Question 4776

Topic: 4. Pediatrics

A neonate with macrocephaly, frontal bossing, and rhizomelic short stature is diagnosed with achondroplasia. Which of the following gene mutations is responsible for this condition?

. COL1A1
. FGFR3
. COMP
. RUNX2
. FBN1

Correct Answer & Explanation

. COL1A1

Explanation

Achondroplasia is caused by an activating (gain-of-function) mutation in the Fibroblast Growth Factor Receptor 3 (FGFR3) gene. This mutation pathologically inhibits chondrocyte proliferation in the proliferative zone of the physis, leading to impaired endochondral ossification.

Question 4777

Topic: 4. Pediatrics

An 8-week-old infant presents with a left-sided neck mass and the head tilted to the left with the chin rotated to the right. A diagnosis of congenital muscular torticollis is made. What other orthopedic screening is most critical for this infant?

. Radiographs of the cervical spine
. Ultrasound of the hips
. Echocardiogram
. MRI of the brain and brainstem
. Renal ultrasound

Correct Answer & Explanation

. Radiographs of the cervical spine

Explanation

Congenital muscular torticollis (CMT) is strongly associated with developmental dysplasia of the hip (DDH), occurring in up to 20% of cases. An ultrasound of the hips is recommended for screening in all infants with CMT.

Question 4778

Topic: Pediatric Lower Extremity

A 12-year-old active boy complains of anterior knee pain exacerbated by jumping. Examination reveals a prominent, tender tibial tubercle. Radiographs show fragmentation of the tibial tubercle apophysis. What is the most appropriate initial management?

. Cylindrical cast immobilization for 6 weeks
. Surgical excision of the ossicle
. Activity modification, NSAIDs, and physical therapy
. Corticosteroid injection into the patellar tendon
. Drilling of the tibial tubercle

Correct Answer & Explanation

. Cylindrical cast immobilization for 6 weeks

Explanation

Osgood-Schlatter disease is a traction apophysitis of the tibial tubercle. It is self-limiting and best managed conservatively with activity modification, stretching, and non-steroidal anti-inflammatory drugs (NSAIDs).

Question 4779

Topic: Pediatric Hip

A 28-year-old professional hockey player presents with chronic groin pain exacerbated by hip flexion and internal rotation. Radiographs demonstrate a prominent bony bump at the anterosuperior femoral head-neck junction with an alpha angle of 65 degrees. He is diagnosed with Femoroacetabular Impingement (FAI). Which of the following conditions is a known risk factor for the development of this specific type of lesion?

. Developmental Dysplasia of the Hip (DDH)
. Slipped Capital Femoral Epiphysis (SCFE)
. Legg-Calve-Perthes Disease
. Acetabular retroversion
. Coxa profunda

Correct Answer & Explanation

. Developmental Dysplasia of the Hip (DDH)

Explanation

The patient has a Cam lesion, characterized by an abnormal femoral head-neck offset (alpha angle >50-55 degrees). A mild or subclinical Slipped Capital Femoral Epiphysis (SCFE) leads to an anterior and superior metaphyseal prominence, a well-known cause of secondary Cam-type FAI. Acetabular retroversion and coxa profunda are associated with Pincer-type FAI (acetabular overcoverage).

Question 4780

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains an extension-type Gartland III supracondylar humerus fracture that is posterolaterally displaced. Which nerve is at the highest risk of injury, and what is its classic clinical manifestation?
. Ulnar nerve; weak finger abduction
. Radial nerve; inability to extend the wrist
. Anterior interosseous nerve; inability to flex the IP joint of the thumb and DIP of the index finger
. Median nerve; complete loss of sensation over the thenar eminence
. Musculocutaneous nerve; weak elbow flexion

Correct Answer & Explanation

. Anterior interosseous nerve; inability to flex the IP joint of the thumb and DIP of the index finger

Explanation

Posterolateral displacement of the distal fragment causes the proximal metaphyseal spike to displace anteromedially, jeopardizing the median nerve and its branch, the anterior interosseous nerve (AIN). AIN injury results in inability to make an "OK" sign.

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