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4. Pediatrics MCQs

Practice Set 234 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 4661

Topic: 4. Pediatrics
A 4-year-old boy with multiple café-au-lait spots is diagnosed with Neurofibromatosis Type 1 (NF1) and presents with anterolateral bowing of the tibia. A frank pseudarthrosis has developed. What is the standard, most reliable orthopedic management to achieve union?
. Simple observation and long leg casting
. Resection of the pseudarthrosis, autogenous bone grafting, and intramedullary rod fixation
. Pulsed electromagnetic field therapy and bracing
. Immediate below-knee amputation
. Epiphysiodesis of the contralateral limb

Correct Answer & Explanation

. Resection of the pseudarthrosis, autogenous bone grafting, and intramedullary rod fixation

Explanation

Congenital pseudarthrosis of the tibia (CPT) is strongly associated with NF1 (anterolateral bowing). Achieving union is notoriously difficult. The standard and most reliable surgical approach is aggressive resection of the hamartomatous pseudarthrosis tissue back to healthy bleeding bone, voluminous autogenous bone grafting (or BMP), and sturdy intramedullary fixation (e.g., Williams rod or Fassier-Duval rod) that crosses the ankle joint if necessary. Cast immobilization or bracing alone will not achieve union once a pseudarthrosis is present.

Question 4662

Topic: 4. Pediatrics

Multiple hereditary exostoses (MHE) is a disorder characterized by multiple osteochondromas. It is inherited in an autosomal dominant pattern and is primarily caused by mutations in genes that encode glycosyltransferases. Which genes are implicated in this disorder?

. FGFR3 and FGFR1
. COMP and MATN3
. COL1A1 and COL1A2
. EXT1 and EXT2
. CBFA1 / RUNX2

Correct Answer & Explanation

. FGFR3 and FGFR1

Explanation

Multiple hereditary exostoses (MHE) is caused by mutations in the EXT1 (chromosome 8) or EXT2 (chromosome 11) genes. These genes are tumor suppressors that encode glycosyltransferases responsible for synthesizing heparan sulfate, which is vital for normal chondrocyte proliferation and Indian hedgehog (Ihh) signaling at the physis. FGFR3 is associated with achondroplasia; COMP with multiple epiphyseal dysplasia; COL1A1 with osteogenesis imperfecta; and CBFA1/RUNX2 with cleidocranial dysplasia.

Question 4663

Topic: Pediatric Hip

A 6-week-old female is being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH).

At her 2-week follow-up, the parents report she is not kicking her left leg as much. On examination, she has decreased active extension of the left knee, though passive range of motion is normal. What is the most likely cause of this finding?

. Avascular necrosis of the femoral head
. Obturator nerve palsy due to excessive abduction
. Femoral nerve palsy due to hyperflexion
. Sciatic nerve palsy due to tight posterior straps
. Inferior dislocation of the hip

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Hyperflexion of the hips in a Pavlik harness can cause compression of the femoral nerve, leading to a transient femoral nerve palsy. This presents clinically as decreased active extension of the knee. Treatment involves adjusting the anterior straps to decrease the degree of hip flexion or temporarily discontinuing the harness until function returns.

Question 4664

Topic: Pediatric Hip

A 13-year-old obese male with a stable left Slipped Capital Femoral Epiphysis (SCFE) undergoes in situ pinning with a single cannulated screw.

Six months postoperatively, he develops severe, constant hip pain and a significantly restricted range of motion in all planes. Radiographs demonstrate concentric joint space narrowing without hardware failure. What is the most likely diagnosis?

. Avascular necrosis
. Chondrolysis
. Septic arthritis
. Screw cut-out
. Femoroacetabular impingement

Correct Answer & Explanation

. Avascular necrosis

Explanation

Chondrolysis is a severe complication of SCFE, highly associated with unrecognized intra-articular screw penetration. It presents with pain, global stiffness, and diffuse, concentric joint space narrowing on radiographs. Avascular necrosis typically presents with subchondral collapse and sclerosis rather than global joint space narrowing.

Question 4665

Topic: Pediatric Upper Extremity & Spine
A 5-year-old boy presents with an extension-type Gartland III supracondylar humerus fracture after a fall. On examination, his hand is well-perfused (pink) with brisk capillary refill, but the radial pulse is absent. What is the most appropriate initial management?
. Immediate open vascular exploration
. Urgent closed reduction and percutaneous pinning, followed by reassessment
. CT angiography of the upper extremity
. Prophylactic forearm fasciotomy
. Admission for elevation and observation in a splint

Correct Answer & Explanation

. Urgent closed reduction and percutaneous pinning, followed by reassessment

Explanation

The presentation of a 'pink, pulseless' hand with a displaced supracondylar fracture dictates urgent closed reduction and percutaneous pinning (CRPP) as the initial step. Often, the pulse returns after reduction removes the tethering or kinking of the brachial artery. If the hand remains pink and well-perfused after CRPP, observation is appropriate even if the pulse remains absent. Open exploration is indicated for a 'white, pulseless' hand that does not improve after reduction.

Question 4666

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Anteroposterior radiographs of the pelvis demonstrate that exactly 50% of the lateral pillar height is maintained on the affected side. According to the Herring lateral pillar classification, into which group does this patient fall?
. Group A
. Group B
. Group B/C
. Group C
. Group D

Correct Answer & Explanation

. Group B/C

Explanation

The Herring Lateral Pillar classification is a strong prognostic indicator in LCP. Group A has 100% height maintenance; Group B has >50% height; Group C has <50% height. Group B/C is a distinct, intermediate category where exactly 50% of the pillar height is maintained or the pillar is very narrow (2-3 mm). Patients in Group B/C have outcomes worse than Group B but better than Group C.

Question 4667

Topic: 4. Pediatrics
A newborn is diagnosed with congenital scoliosis secondary to a fully segmented hemivertebra at T8. Which of the following is the most appropriate routine screening protocol to order next to evaluate for frequently associated anomalies?
. MRI of the brain
. Renal ultrasound and echocardiogram
. CT scan of the chest
. Complete skeletal survey
. Genetic testing for FGFR3 mutation

Correct Answer & Explanation

. Renal ultrasound and echocardiogram

Explanation

Congenital scoliosis is highly associated with VACTERL anomalies. Genitourinary anomalies (e.g., unilateral renal agenesis) occur in 20-30% of patients, and congenital heart defects occur in 10-15%. Therefore, a renal ultrasound and an echocardiogram are mandatory screening tests. An MRI of the entire spine is also indicated to rule out intraspinal anomalies (e.g., tethered cord), but an MRI of the brain is not.

Question 4668

Topic: 4. Pediatrics

In a 6-year-old child with spastic quadriplegic cerebral palsy (GMFCS Level V), routine hip surveillance is indicated. What is the most important, standardized radiographic parameter used to monitor the progression of hip displacement in this population?

. Center-edge angle of Wiberg
. Reimer's migration percentage
. Acetabular index
. Alpha angle of Graf
. Neck-shaft angle

Correct Answer & Explanation

. Center-edge angle of Wiberg

Explanation

Reimer's migration percentage (MP) is the gold standard measurement for monitoring hip displacement in children with cerebral palsy. It quantifies the percentage of the ossified femoral head that is displaced outside the lateral margin of the acetabulum (Perkin's line). An MP > 30% indicates subluxation and generally warrants increased surveillance or orthopedic intervention.

Question 4669

Topic: 4. Pediatrics

A 3-year-old girl, who is at the 95th percentile for weight and began walking at 9 months of age, presents with progressive bilateral genu varum.

Radiographs reveal an abrupt medial beaking of the proximal tibial metaphysis and a metaphyseal-diaphyseal angle (Drennan's angle) of 18 degrees. What is the most likely diagnosis?

. Physiologic bowing
. Infantile Blount disease
. Achondroplasia
. Hypophosphatemic rickets
. Osteogenesis imperfecta

Correct Answer & Explanation

. Physiologic bowing

Explanation

Infantile Blount disease (tibia vara) classicly affects overweight children who are early walkers. Radiographs show varus centered at the proximal tibia with medial metaphyseal beaking. A metaphyseal-diaphyseal angle > 16 degrees has a high predictive value for progression to true Blount disease, differentiating it from physiologic bowing, which usually has an angle < 11 degrees.

Question 4670

Topic: 4. Pediatrics

A 5-year-old boy with blue sclerae, multiple previous fractures, and mild short stature is diagnosed with Osteogenesis Imperfecta Type I. Which of the following gene mutations is most commonly responsible for this condition?

. FGFR3
. COMP
. COL1A1 or COL1A2
. COL2A1
. RUNX2

Correct Answer & Explanation

. FGFR3

Explanation

Osteogenesis Imperfecta (OI) is a disorder of type I collagen, the major structural protein in bone. Over 90% of OI cases are caused by mutations in either the COL1A1 or COL1A2 genes. Type I OI is generally the mildest and most common form, typically resulting from a null mutation leading to a quantitative deficiency of structurally normal type I collagen.

Question 4671

Topic: 4. Pediatrics
A 13-year-old girl sustains an ankle injury during a soccer match. Radiographs reveal an isolated Salter-Harris III fracture of the anterolateral distal tibial epiphysis (Tillaux fracture). Which of the following describes the anatomical sequence of distal tibial physeal closure that predisposes adolescents to this specific fracture pattern?
. Anterolateral to posteromedial
. Central to peripheral
. Central to medial, then laterally
. Posteromedial to anterolateral
. Medial to central, then laterally

Correct Answer & Explanation

. Central to medial, then laterally

Explanation

The distal tibial physis begins to close around 12-14 years of age. The sequence of closure begins centrally, proceeds medially, and finishes laterally (the anterolateral quadrant is the last to close). Because the anterolateral physis remains open while the rest is fused, it is vulnerable to avulsion by the anterior inferior tibiofibular ligament during an external rotation injury, resulting in a Tillaux fracture.

Question 4672

Topic: 4. Pediatrics

A 12-year-old elite Little League pitcher complains of progressively worsening pain in his throwing shoulder during the late cocking phase. Radiographs show widening and sclerosis of the proximal humeral physis. What is the primary pathophysiology of this condition (Little League Shoulder)?

. Avulsion fracture of the greater tuberosity
. Partial rotator cuff tear
. Salter-Harris I stress fracture of the proximal humeral physis
. Superior labrum anterior and posterior (SLAP) tear
. Glenohumeral internal rotation deficit (GIRD)

Correct Answer & Explanation

. Avulsion fracture of the greater tuberosity

Explanation

Little League shoulder is an overuse injury characterized by a stress reaction or a Salter-Harris type I stress fracture of the proximal humeral physis. It is caused by repetitive torsional stresses during the throwing motion. Treatment primarily consists of rest and cessation of throwing until symptoms resolve and the physis appears normal radiographically.

Question 4673

Topic: Pediatric Hip

A 12-year-old obese male presents with severe left hip pain and is completely unable to bear weight, even with the assistance of crutches. Radiographs confirm a severe left Slipped Capital Femoral Epiphysis (SCFE). Which of the following best describes his classification and the associated risk of the most catastrophic complication?

. Stable SCFE; highest risk is chondrolysis
. Stable SCFE; highest risk is avascular necrosis (AVN)
. Unstable SCFE; highest risk is chondrolysis
. Unstable SCFE; highest risk is avascular necrosis (AVN)
. Acute-on-chronic SCFE; highest risk is femoroacetabular impingement

Correct Answer & Explanation

. Stable SCFE; highest risk is chondrolysis

Explanation

According to the Loder classification, an unstable SCFE is defined by the inability to bear weight, with or without crutches. Unstable SCFE carries a significantly higher risk of avascular necrosis (AVN), occurring in up to 50% of cases.

Question 4674

Topic: Pediatric Hip

An 18-month-old female with late-presenting Developmental Dysplasia of the Hip (DDH) undergoes closed reduction and spica casting in the operating room. To minimize the risk of iatrogenic avascular necrosis (AVN) of the femoral head, which of the following extreme positions must be strictly avoided during casting?

. Extreme flexion
. Extreme extension
. Extreme abduction
. Extreme adduction
. Extreme internal rotation

Correct Answer & Explanation

. Extreme flexion

Explanation

Extreme abduction places excessive pressure on the cartilaginous femoral head and compresses the medial circumflex femoral artery. This is the most significant risk factor for iatrogenic AVN following closed reduction and spica casting for DDH.

Question 4675

Topic: Pediatric Hip
A 9-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs demonstrate that less than 50% of the lateral pillar height is maintained. Based on the Herring Lateral Pillar Classification, which of the following is true regarding his prognosis and management?
. He is classified as Lateral Pillar A and will have a good outcome without surgery.
. He is classified as Lateral Pillar B and should be treated with immediate spica casting.
. He is classified as Lateral Pillar C and has a poor prognosis regardless of treatment, though containment surgery may be considered.
. He is classified as Lateral Pillar B/C and requires hinged distraction external fixation.
. He is classified as Lateral Pillar C and is best managed with isolated adductor tenotomy.

Correct Answer & Explanation

. He is classified as Lateral Pillar C and has a poor prognosis regardless of treatment, though containment surgery may be considered.

Explanation

Herring Lateral Pillar Type C is defined by <50% maintenance of the lateral pillar height and carries the poorest prognosis. In children over 8 years old with severe involvement, while surgical containment (femoral or pelvic osteotomy) may be attempted, the long-term outcome remains guarded.

Question 4676

Topic: Pediatric Lower Extremity
A 4-year-old boy previously treated for idiopathic clubfoot with the Ponseti method presents with a relapsed deformity. Gait analysis reveals dynamic supination of the foot during the swing phase. Passive range of motion demonstrates a fully correctable deformity. What is the most appropriate definitive management?
. Repeat Achilles tendon lengthening
. Tibialis anterior tendon transfer to the lateral cuneiform
. Tibialis posterior tendon transfer to the dorsal foot
. Split anterior tibial tendon transfer (SPLATT)
. Lateral column lengthening (Evans osteotomy)

Correct Answer & Explanation

. Tibialis anterior tendon transfer to the lateral cuneiform

Explanation

Dynamic supination during the swing phase in a relapsed clubfoot is typically caused by an overactive tibialis anterior. If the foot is passively correctable, a full tibialis anterior tendon transfer (TATT) to the lateral (third) cuneiform is the treatment of choice.

Question 4677

Topic: Pediatric Lower Extremity

A 3-year-old female presents with progressive unilateral genu varum. Standing lower extremity radiographs are obtained. Measurement of the metaphyseal-diaphyseal angle (Drennan's angle) is most predictive of progression to infantile Blount's disease when it exceeds what threshold?

. 5 degrees
. 9 degrees
. 11 degrees
. 16 degrees
. 22 degrees

Correct Answer & Explanation

. 5 degrees

Explanation

The metaphyseal-diaphyseal angle (Drennan's angle) is used to differentiate physiologic bowing from infantile Blount's disease. An angle greater than 16 degrees has a high predictive value for progression to Blount's disease.

Question 4678

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains a completely displaced, extension-type supracondylar humerus fracture (Gartland Type III). Upon presentation, his hand is pale and pulseless. Following closed reduction and percutaneous pinning in the operating room, the hand becomes warm and pink with a capillary refill of 2 seconds, but the radial pulse remains unpalpable. What is the most appropriate next step in management?
. Immediate exploration of the brachial artery
. Removal of pins and open reduction
. Observation and hospital admission for neurovascular checks
. Immediate sympathectomy
. Application of a hyperflexion cast

Correct Answer & Explanation

. Observation and hospital admission for neurovascular checks

Explanation

A "pink, pulseless" hand after reduction of a supracondylar humerus fracture indicates adequate collateral perfusion. The standard of care is close observation and admission, as the pulse frequently returns within a few days.

Question 4679

Topic: 4. Pediatrics

A 7-year-old non-ambulatory child with spastic quadriplegic cerebral palsy presents for a routine evaluation. Pelvic radiographs demonstrate a Reimers Migration Percentage of 45% bilaterally. He is currently painless. What is the most appropriate treatment recommendation?

. Observation with repeat radiographs in 1 year
. Botulinum toxin injection to the adductors
. Bilateral adductor and psoas tenotomies
. Proximal femoral varus derotational osteotomies (VDRO) combined with pelvic osteotomies
. Total hip arthroplasty

Correct Answer & Explanation

. Observation with repeat radiographs in 1 year

Explanation

In children with cerebral palsy, a Reimers Migration Percentage >40% indicates significant hip subluxation with a high risk of progression to dislocation. Comprehensive bony reconstruction with VDRO and a volume-reducing pelvic osteotomy (e.g., Dega) is indicated.

Question 4680

Topic: 4. Pediatrics

A 13-year-old female sustains a fracture of the anterolateral aspect of her distal tibial epiphysis after an external rotation injury. This fracture pattern (Tillaux fracture) occurs specifically due to the asymmetrical closure of the distal tibial physis. In what sequence does the normal distal tibial physis close?

. Central, Anteromedial, Posteromedial, Lateral
. Lateral, Central, Medial, Posterior
. Posteromedial, Lateral, Central, Anteromedial
. Medial, Lateral, Central, Posterior
. Anterolateral, Posteromedial, Central, Lateral

Correct Answer & Explanation

. Central, Anteromedial, Posteromedial, Lateral

Explanation

The distal tibial physis closes in a characteristic sequence: first centrally, then anteromedially, followed by posteromedially, and finally laterally. Because the anterolateral physis is the last to close, it is susceptible to avulsion by the anterior inferior tibiofibular ligament (Tillaux fracture).

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