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4. Pediatrics MCQs

Practice Set 237 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 4721

Topic: 4. Pediatrics

Which of the following is considered an absolute contraindication for finger replantation?

. Thumb amputation
. Multiple digit amputations
. Clean guillotine amputation of a single digit in zone II in an adult
. Amputation in a child
. Prolonged warm ischemia time (>12 hours for a digit)

Correct Answer & Explanation

. Thumb amputation

Explanation

Absolute contraindications for replantation include prolonged warm ischemia time (typically >12 hours for a digit or >6 hours for a major limb), severe crush or avulsion injuries with multiple level tissue damage, and life-threatening concomitant injuries. Thumb amputations, multiple digits, and pediatric amputations are strong indications FOR replantation. Single digit amputations in Zone II in adults are relative contraindications or controversial due to poor functional outcomes (stiffness).

Question 4722

Topic: Pediatric Upper Extremity & Spine
A neonate presents with bilateral shortened forearms, radially deviated hands, and absent radii on radiographs. Interestingly, both thumbs are present and appear structurally normal. Which of the following genetic syndromes is most likely in this patient?
. Holt-Oram syndrome
. Fanconi anemia
. VATER association
. Thrombocytopenia-absent radius (TAR) syndrome
. VACTERL syndrome

Correct Answer & Explanation

. Thrombocytopenia-absent radius (TAR) syndrome

Explanation

Thrombocytopenia-absent radius (TAR) syndrome is uniquely characterized by bilateral absence of the radii but with preservation of the thumbs. In other syndromes associated with radial longitudinal deficiency (such as Fanconi anemia, Holt-Oram, and VACTERL), if the radius is absent or hypoplastic, the thumb is also typically absent or hypoplastic.

Question 4723

Topic: Pediatric Upper Extremity & Spine
A newborn presents with bilateral absent radii and severely radially deviated hands. Examination reveals that both thumbs are perfectly formed and present. An echocardiogram is normal. Laboratory tests reveal severe thrombocytopenia. Which genetic mutation is most likely responsible for this child's syndrome?
. RBM8A
. TBX5
. FANCA
. SALL4
. FGFR2

Correct Answer & Explanation

. RBM8A

Explanation

The child has Thrombocytopenia-Absent Radius (TAR) syndrome, which is unique among the radial longitudinal deficiencies because the thumbs are present. This distinguishes it from Fanconi anemia (FANCA) and Holt-Oram syndrome (TBX5), where thumbs are typically absent or hypoplastic. TAR syndrome is caused by a microdeletion at 1q21.1 affecting the RBM8A gene.

Question 4724

Topic: Pediatric Upper Extremity & Spine
A newborn presents with radial clubhand and an absent thumb. Echocardiography reveals an atrial septal defect. Hematologic workup is normal. What is the most likely diagnosis?
. Fanconi anemia
. Holt-Oram syndrome
. TAR syndrome
. VACTERL association
. Apert syndrome

Correct Answer & Explanation

. Holt-Oram syndrome

Explanation

Holt-Oram syndrome is an autosomal dominant condition characterized by radial longitudinal deficiency and congenital heart defects, most commonly atrial septal defects (ASD) or ventricular septal defects (VSD). Unlike Fanconi anemia, bone marrow function is normal.

Question 4725

Topic: 4. Pediatrics
A 14-year-old boy presents after a skateboard injury with a Salter-Harris type III fracture of the anterolateral aspect of his distal tibia (Tillaux fracture). Which ligament is responsible for the avulsion of this specific bony fragment?
. Posterior inferior tibiofibular ligament (PITFL)
. Anterior talofibular ligament (ATFL)
. Anterior inferior tibiofibular ligament (AITFL)
. Calcaneofibular ligament (CFL)
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament (AITFL)

Explanation

A Tillaux fracture is a juvenile Salter-Harris III avulsion fracture of the anterolateral distal tibial epiphysis. It occurs because the central and medial aspects of the distal tibial physis close before the lateral aspect. External rotation forces cause the anterior inferior tibiofibular ligament (AITFL) to pull off this anterolateral quadrant.

Question 4726

Topic: Pediatric Hip

A 6-week-old female infant is undergoing screening for developmental dysplasia of the hip (DDH). An ultrasound of the hip is provided:

In the Graf classification system, the alpha angle is measured to assess the bony roof. Which anatomic structure determines the primary baseline used to establish this angle?

. Bony roof of the acetabulum
. Cartilaginous labrum
. Straight portion of the ilium
. Triradiate cartilage
. Center of the femoral head

Correct Answer & Explanation

. Bony roof of the acetabulum

Explanation

In the Graf ultrasound method for DDH, three lines are drawn. The primary baseline is drawn parallel to the straight portion of the ilium. The second line is drawn along the bony roof of the acetabulum to measure the alpha angle, while the third line is drawn along the cartilaginous roof to measure the beta angle.

Question 4727

Topic: Pediatric Hip

A 12-year-old obese boy presents with left hip pain and an obligatory external rotation with hip flexion. The radiograph is shown:

He undergoes in situ pinning for a Slipped Capital Femoral Epiphysis (SCFE). Which of the following is the most reliable predictor for a future contralateral slip?

. Chronologic age
. Degree of initial slip
. Modified Oxford bone age
. Body Mass Index (BMI)
. Duration of symptoms prior to surgery

Correct Answer & Explanation

. Chronologic age

Explanation

The modified Oxford bone age is the most accurate predictor of a contralateral slip in patients with a unilateral SCFE. A score derived from pelvic radiographs helps determine skeletal maturity; a score of 16 indicates a high risk for a subsequent contralateral slip, justifying prophylactic pinning.

Question 4728

Topic: Pediatric Hip

An 8-year-old boy presents with a painless limp of 6 months duration. Radiographs are provided:

According to the Herring classification for Legg-Calve-Perthes disease, which specific anatomic region is evaluated to determine the prognosis?

. Height of the lateral pillar of the epiphysis
. Extent of metaphyseal cysts
. Subchondral fracture extent
. Sphericity of the femoral head
. Medial joint space widening

Correct Answer & Explanation

. Height of the lateral pillar of the epiphysis

Explanation

The Herring classification focuses on the height of the lateral pillar (the lateral one-third of the epiphysis) on an AP radiograph during the fragmentation stage of Perthes disease. Type A has no involvement, Type B maintains >50% lateral pillar height, and Type C has <50% height, which carries the worst prognosis.

Question 4729

Topic: Pediatric Lower Extremity

A 2-week-old infant is diagnosed with the condition shown:

The Ponseti method is initiated. What is the correct initial manipulative step to correct the cavus deformity prior to cast application?

. Pronation of the forefoot
. Elevation of the first ray to supinate the forefoot
. Direct pressure over the calcaneocuboid joint
. Maximal dorsiflexion of the ankle
. Eversion of the hindfoot

Correct Answer & Explanation

. Pronation of the forefoot

Explanation

The first step in the Ponseti casting technique for idiopathic clubfoot is correcting the cavus. This is achieved by elevating the first metatarsal (first ray), which effectively supinates the forefoot so that it aligns with the supinated hindfoot. Subsequent casts will abduct the forefoot around the head of the talus.

Question 4730

Topic: 4. Pediatrics

When evaluating a non-ambulatory 14-year-old patient with spastic quadriplegic cerebral palsy who has developed a progressive spinal deformity, what is the most common scoliotic curve pattern observed?

. Right thoracic curve
. Left lumbar curve
. Double major curve
. Long sweeping C-shaped curve
. Short angular kyphoscoliosis

Correct Answer & Explanation

. Right thoracic curve

Explanation

Neuromuscular scoliosis, particularly in severe forms of cerebral palsy (spastic quadriplegia), classically presents as a long, sweeping C-shaped curve that often extends into the pelvis, causing pelvic obliquity and difficulty with seating. This contrasts with the classic right thoracic S-shaped curve seen in adolescent idiopathic scoliosis.

Question 4731

Topic: Pediatric Upper Extremity & Spine
A newborn presents with bilateral absent radii and absent thumbs (radial clubhands). Before considering any surgical intervention, which of the following is an absolute mandatory hematologic screening test?
. Hemoglobin electrophoresis
. Peripheral blood smear
. Chromosomal breakage testing with diepoxybutane
. Factor VIII assay
. Bone marrow biopsy

Correct Answer & Explanation

. Chromosomal breakage testing with diepoxybutane

Explanation

Radial clubhand can be associated with multiple syndromes, notably Fanconi anemia, Holt-Oram, TAR, and VACTERL. Fanconi anemia is a fatal aplastic anemia if unrecognized, and surgery is contraindicated until it is ruled out. Chromosomal breakage testing using diepoxybutane (DEB) or mitomycin C is the gold standard for diagnosis.

Question 4732

Topic: 4. Pediatrics

In a child with developmental coxa vara, which of the following radiographic parameters is the strongest indication for a valgus proximal femoral osteotomy?

. Neck-shaft angle < 130 degrees
. Hilgenreiner epiphyseal angle (HEA) > 60 degrees
. Articulo-trochanteric distance < 0
. Sharp's angle > 45 degrees
. Center-edge angle < 20 degrees

Correct Answer & Explanation

. Neck-shaft angle < 130 degrees

Explanation

The Hilgenreiner Epiphyseal Angle (HEA) is the angle between Hilgenreiner's line and a line drawn through the proximal femoral physis. A normal HEA is < 25 degrees. An HEA > 60 degrees is associated with inevitable progression of the coxa vara and is a definitive indication for surgical intervention (valgus osteotomy).

Question 4733

Topic: 4. Pediatrics

A 10-year-old girl sustained a distal femoral physeal fracture 2 years ago and now presents with a progressive valgus deformity. MRI demonstrates a focal central physeal bridge. What is the generally accepted upper limit of physeal cross-sectional area involvement that remains amenable to bridge resection and interposition grafting?

. 10%
. 25%
. 50%
. 75%
. 90%

Correct Answer & Explanation

. 10%

Explanation

Physeal bar resection with interposition grafting (using fat, cranioplast, or bone wax) is generally indicated if the child has at least 2 years of skeletal growth remaining and the physeal bar involves less than 50% of the total cross-sectional area of the physis.

Question 4734

Topic: 4. Pediatrics

The Wrisberg variant of the discoid lateral meniscus typically presents with a "snapping knee" in young children. This specific variant is anatomically defined by the congenital absence of which of the following structures?

. Anterior meniscofemoral ligament
. Meniscofibular ligament
. Posterior meniscotibial (coronary) ligament
. Transverse intermeniscal ligament
. Popliteomeniscal fascicles

Correct Answer & Explanation

. Anterior meniscofemoral ligament

Explanation

The Wrisberg variant of the discoid lateral meniscus lacks the normal posterior meniscotibial (coronary) ligament attachments, making it hypermobile. Its only posterior attachment is the meniscofemoral ligament of Wrisberg, leading to extrusion into the joint during extension and the classic 'snapping knee' presentation.

Question 4735

Topic: 4. Pediatrics

A 3-year-old child presents with bilateral bowing of the legs, worse on the left. Radiographs reveal depression of the medial tibial plateau with beaking of the medial metaphysis.

What is the primary pathological process driving this infantile deformity?

. Avascular necrosis of the medial epiphysis
. Hyperphysiologic compression inhibiting medial physeal growth (Heuter-Volkmann principle)
. Traction apophysitis of the pes anserinus
. Congenital failure of formation of the medial tibial plateau
. Vitamin D deficiency leading to osteomalacia

Correct Answer & Explanation

. Avascular necrosis of the medial epiphysis

Explanation

The clinical scenario and radiograph describe infantile Blount disease (tibia vara). The primary pathogenesis involves the Heuter-Volkmann principle, where excessive compressive forces on the medial aspect of the proximal tibial physis inhibit its growth, while the lateral physis continues to grow normally, exacerbating the varus deformity.

Question 4736

Topic: 4. Pediatrics
A 6-year-old child falls from monkey bars and sustains a displaced supracondylar humerus fracture. Upon presentation, the hand is pink but pulseless. After closed reduction and percutaneous pinning, the hand remains pink and well-perfused (capillary refill < 2 seconds), but the radial pulse remains absent. What is the most appropriate next step in management?
. Immediate exploration of the brachial artery
. Perform a CT angiogram of the upper extremity
. Observe and admit for 24 to 48 hours with serial neurovascular checks
. Remove all pins and perform an open reduction
. Administer intravenous heparin

Correct Answer & Explanation

. Observe and admit for 24 to 48 hours with serial neurovascular checks

Explanation

In a 'pink, pulseless' hand following reduction and pinning of a supracondylar humerus fracture, the hand is adequately perfused through collateral circulation despite the lack of a palpable radial pulse. The standard of care is admission for 24-48 hours of observation with serial neurovascular exams. Vascular exploration is reserved for a 'white, pulseless' hand that does not improve with fracture reduction.

Question 4737

Topic: 4. Pediatrics
A 14-year-old adolescent sustains an ankle injury while playing soccer. Imaging demonstrates a Salter-Harris III fracture of the anterolateral distal tibia. What is the primary deforming force and typical pattern of physeal closure in the distal tibia that predisposes to this specific fracture pattern?
. Anterior talofibular ligament; physis closes lateral to medial
. Anterior inferior tibiofibular ligament; physis closes central to medial then lateral
. Calcaneofibular ligament; physis closes lateral to central to medial
. Posterior inferior tibiofibular ligament; physis closes medial to lateral
. Deltoid ligament; physis closes central to medial then lateral

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament; physis closes central to medial then lateral

Explanation

This describes a Tillaux fracture. The distal tibial physis closes in a specific predictable pattern over an 18-month period: central, then anteromedial, then posteromedial, and finally the anterolateral portion. During this transitional period, the anterolateral physis remains open and vulnerable. An external rotation force causes the anterior inferior tibiofibular ligament (AITFL) to avulse the anterolateral epiphysis.

Question 4738

Topic: Pediatric Hip

A 13-year-old boy with a BMI of 32 presents with acute-on-chronic groin pain. He is unable to bear weight. Radiographs show a displaced Slipped Capital Femoral Epiphysis (SCFE).

Based on the Loder classification, what is the primary clinical significance of his inability to bear weight?

. It indicates an associated labral tear
. It defines an unstable SCFE, which has a much higher rate of avascular necrosis (AVN)
. It indicates bilateral involvement is highly likely
. It demonstrates impending slip progression requiring an emergent open reduction
. It precludes the use of in-situ pinning

Correct Answer & Explanation

. It indicates an associated labral tear

Explanation

The Loder classification divides SCFE into stable (able to bear weight with or without crutches) and unstable (unable to bear weight even with crutches). Unstable SCFE has a significantly higher rate of avascular necrosis (AVN), reported to be between 10% and 47%, compared to less than 10% for stable slips.

Question 4739

Topic: 4. Pediatrics

You are evaluating a 6-year-old girl with spastic quadriplegic cerebral palsy (GMFCS Level V). Her recent AP pelvis radiograph demonstrates a Reimer's migration percentage of 55% in the right hip. She is currently asymptomatic. What is the most appropriate recommendation?

. Continued observation with annual radiographs
. Botulinum toxin injections to the adductors and iliopsoas
. Varus derotational osteotomy (VDRO) with or without a pelvic osteotomy
. Proximal femoral resection (Girdlestone procedure)
. Adductor tenotomy and physical therapy

Correct Answer & Explanation

. Continued observation with annual radiographs

Explanation

In cerebral palsy hip surveillance, a Reimer's migration percentage >30% warrants close monitoring, but a migration percentage >50% generally warrants surgical reconstruction (VDRO +/- pelvic osteotomy), even in an asymptomatic patient. This is to prevent progression to a painful, irreducible, dislocated hip.

Question 4740

Topic: 4. Pediatrics
A 4-year-old boy with a known diagnosis of Osteogenesis Imperfecta Type I presents to the clinic. He has a history of multiple low-energy fractures. Which of the following describes the most likely genetic defect and its phenotypic expression in this patient?
. Quantitative defect in type I collagen; blue sclerae and normal stature
. Qualitative defect in type I collagen; white sclerae and dentinogenesis imperfecta
. Defect in FGFR3; rhizomelic shortening and frontal bossing
. Defect in COMP; short trunk dwarfism and atlantoaxial instability
. Defect in type II collagen; epiphyseal dysplasia and cleft palate

Correct Answer & Explanation

. Quantitative defect in type I collagen; blue sclerae and normal stature

Explanation

Osteogenesis Imperfecta (OI) Type I is the most common and mildest form. It is characterized by a quantitative defect (decreased production) in normal Type I collagen, leading to bone fragility, blue sclerae, and near-normal stature. Types II, III, and IV involve qualitative defects (structurally abnormal collagen) and are typically more severe.

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