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4. Pediatrics MCQs

Practice Set 265 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 5281

Topic: Pediatric Hip

A 13-year-old obese male presents with a 3-week history of left groin and knee pain. He walks with an antalgic limp and externally rotates the left leg during the swing phase. On physical exam, as the left hip is flexed, it obligatorily externally rotates. Radiographs confirm a Slipped Capital Femoral Epiphysis (SCFE). In which direction does the proximal femoral epiphysis anatomically displace relative to the femoral neck?

. Anterior and Superior
. Posterior and Superior
. Anterior and Inferior
. Posterior and Inferior
. Directly Medial

Correct Answer & Explanation

. Posterior and Inferior

Explanation

In a Slipped Capital Femoral Epiphysis (SCFE), the proximal femoral epiphysis remains relatively stationary within the acetabulum while the femoral metaphysis (neck) displaces anteriorly and superiorly. Thus, describing the displacement of the epiphysisrelative to the neck, it displaces posteriorly and inferiorly.

Question 5282

Topic: Pediatric Hip

In a 12-year-old boy presenting with an isolated, unilateral slipped capital femoral epiphysis (SCFE), which of the following patient factors represents the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Patient age of 14 years
. Female gender
. Presence of panhypopituitarism
. Body mass index > 95th percentile
. A Southwick angle of 20 degrees on the affected side

Correct Answer & Explanation

. Presence of panhypopituitarism

Explanation

Patients with underlying endocrine disorders (such as panhypopituitarism, hypothyroidism, or renal osteodystrophy) have a significantly higher risk of bilateral SCFE (up to 100% in some series) and are strong candidates for prophylactic pinning of the contralateral hip.

Question 5283

Topic: Pediatric Lower Extremity

When correcting idiopathic clubfoot (talipes equinovarus) using the Ponseti method of serial casting, what is the correct physiological sequence in which the individual deformity components must be addressed?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method follows a strict CAVE sequence: Cavus is corrected first (by supinating the forefoot to align with the midfoot), followed by Adductus and Varus simultaneously (by abducting the foot around the fixed talar head), and finally Equinus (which often requires a percutaneous Achilles tenotomy prior to the final cast).

Question 5284

Topic: 4. Pediatrics

A 4-year-old boy presents with disproportionate short stature, frontal bossing, and rhizomelic shortening of the limbs.

Genetic testing confirms a gain-of-function mutation in the FGFR3 gene. The cellular defect associated with this genetic abnormality primarily occurs in which zone of the physis?

. Reserve (resting) zone
. Proliferative zone
. Hypertrophic zone
. Zone of provisional calcification
. Primary spongiosa

Correct Answer & Explanation

. Proliferative zone

Explanation

The patient has achondroplasia, the most common form of disproportionate dwarfism. It is caused by an autosomal dominant gain-of-function mutation in the Fibroblast Growth Factor Receptor 3 (FGFR3) gene. This mutation causes a constant inhibitory signal that suppresses chondrocyte proliferation, primarily affecting the proliferative zone of the physis and leading to defective endochondral ossification.

Question 5285

Topic: 4. Pediatrics

A 10-year-old child sustains a Salter-Harris Type II fracture of the distal radius. The fracture line through the physis primarily propagates through which specific cellular layer?

. Reserve zone
. Proliferative zone
. Zone of hypertrophy
. Zone of provisional calcification
. Primary spongiosa

Correct Answer & Explanation

. Zone of hypertrophy

Explanation

Salter-Harris fractures typically propagate through the zone of hypertrophy in the physis. This zone lacks substantial extracellular matrix (collagen) and is therefore structurally the weakest layer.

Question 5286

Topic: Pediatric Hip

A 9-month-old girl undergoes an attempted closed reduction for developmental dysplasia of the hip (DDH). An intraoperative arthrogram reveals an 'hourglass' constriction preventing concentric reduction. Which of the following anatomic structures is responsible for this specific arthrographic appearance?

. Hypertrophied pulvinar
. Thickened ligamentum teres
. Iliopsoas tendon
. Contracted transverse acetabular ligament
. Inverted limbus

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

In Developmental Dysplasia of the Hip (DDH), an 'hourglass' constriction seen on an intraoperative arthrogram is classically caused by the iliopsoas tendon tightly crossing and compressing the redundant capsule. While the pulvinar, ligamentum teres, transverse acetabular ligament, and inverted limbus can all act as physical blocks to concentric reduction, the iliopsoas tendon specifically produces the hourglass sign. A medial dye pool (>5mm) typically indicates intervening pulvinar or ligamentum teres.

Question 5287

Topic: Pediatric Hip

A 12-year-old boy presents with right knee pain and a limp. He walks with an externally rotated gait. Radiographs reveal a widened and irregular right proximal femoral physis, with Klein's line failing to intersect the lateral epiphysis. Which of the following represents the strongest indication for prophylactic in situ pinning of the contralateral, asymptomatic hip?

. Obesity (BMI > 95th percentile)
. Male gender
. Hypothyroidism
. Age of onset at 14 years
. Grade 1 slip severity on the affected side

Correct Answer & Explanation

. Hypothyroidism

Explanation

Endocrine disorders (such as hypothyroidism, renal osteodystrophy, and growth hormone deficiency) represent a very strong risk factor for bilateral slipped capital femoral epiphysis (SCFE). Patients with these metabolic conditions, as well as those with prior pelvic radiation, typically warrant prophylactic prophylactic pinning of the contralateral hip due to the unusually high incidence of a subsequent slip. Chronologic age < 10 is also an indication.

Question 5288

Topic: Pediatric Hip
A 9-year-old boy is diagnosed with Legg-Calvรฉ-Perthes disease. Radiographs show that the lateral pillar of the femoral head has maintained approximately 60% of its original height. According to the Herring lateral pillar classification, what is his grade, and what is the expected outcome of surgical containment compared to non-operative management?
. Herring A; excellent prognosis without surgery
. Herring B; expected to have a better outcome with surgical containment
. Herring B; expected to have a better outcome with non-operative management
. Herring C; expected to have a better outcome with surgical containment
. Herring C; expected to have a better outcome with non-operative management

Correct Answer & Explanation

. Herring B; expected to have a better outcome with surgical containment

Explanation

This patient has Herring Group B Perthes disease (lateral pillar height between 50% and 100%). Based on the multicenter prospective study by Herring et al., children over the age of 8 years at the onset of symptoms with Group B or B/C border disease have significantly better radiographic outcomes when treated with surgical containment (e.g., femoral or pelvic osteotomy) compared to non-operative treatment.

Question 5289

Topic: Pediatric Lower Extremity

In the treatment of congenital talipes equinovarus (clubfoot) using the Ponseti method, proper cast application must follow a specific sequence. What is the primary pathoanatomy that is addressed during the application of the very first cast?

. Hindfoot equinus
. Hindfoot varus
. Midfoot cavus
. Forefoot adduction
. Tibial internal torsion

Correct Answer & Explanation

. Midfoot cavus

Explanation

The Ponseti method addresses the deformities of clubfoot in a specific sequence: Cavus, Adductus, Varus, and Equinus (CAVE). The very first step is to correct the midfoot cavus. This is accomplished by elevating the first ray, which supinates the forefoot to align it with the hindfoot, effectively unlocking the midtarsal joint and allowing subsequent correction of the adductus and varus.

Question 5290

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains a Gartland type III supracondylar humerus fracture. Examination in the emergency department reveals a 'pink, pulseless' hand. He is immediately taken to the operating room for closed reduction and percutaneous pinning. Following stable fixation, the hand remains well-perfused and pink, with brisk capillary refill, but the radial pulse remains non-palpable by Doppler. What is the most appropriate next step in management?
. Immediate open exploration of the brachial artery
. Removal of the percutaneous pins and open reduction
. Administration of intravenous heparin
. Observation and admission for 24-48 hours
. Prophylactic forearm fasciotomy

Correct Answer & Explanation

. Observation and admission for 24-48 hours

Explanation

The management of a 'pink, pulseless' hand after reduction of a supracondylar fracture relies on tissue perfusion rather than pulse status. If the hand remains well-perfused (warm, pink, brisk capillary refill) following closed reduction and pinning, the standard of care is close observation and admission for 24-48 hours. Collateral circulation is typically sufficient to maintain hand viability, and the pulse often returns over days to weeks. Vascular exploration is indicated for a 'white, pulseless' hand or if perfusion is lost after reduction.

Question 5291

Topic: 4. Pediatrics
A 4-year-old girl is evaluated for a history of multiple low-energy fractures. Physical examination shows blue sclerae, normal stature, and normal dentition. Genetic analysis reveals a null mutation in the COL1A1 gene, resulting in a decreased total amount of structurally normal type I collagen. According to the Sillence classification, what is the diagnosis and its inheritance pattern?
. Type I Osteogenesis Imperfecta; Autosomal Dominant
. Type II Osteogenesis Imperfecta; Autosomal Recessive
. Type III Osteogenesis Imperfecta; Autosomal Dominant
. Type IV Osteogenesis Imperfecta; Autosomal Dominant
. Type IV Osteogenesis Imperfecta; Autosomal Recessive

Correct Answer & Explanation

. Type I Osteogenesis Imperfecta; Autosomal Dominant

Explanation

Type I Osteogenesis Imperfecta is the most common and mildest form. It is characterized by blue sclerae, recurrent childhood fractures that often decrease after puberty, normal stature, and usually normal teeth. Genetically, it is an autosomal dominant condition caused by a quantitative defect (a null mutation) leading to a decreased amount of structurally normal type I collagen. Types II, III, and IV involve qualitative defects (structurally abnormal collagen).

Question 5292

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal girl presents with an adolescent idiopathic scoliosis. Her standing posteroanterior radiograph shows a right thoracic curve measuring 35 degrees. Her Risser stage is 0. What is the most appropriate evidence-based management for this patient?

. Observation with clinical and radiographic follow-up in 6 months
. Prescription of a TLSO brace for 18 to 23 hours per day
. Prescription of a nighttime-only bending brace
. Posterior spinal fusion with pedicle screw instrumentation
. Anterior vertebral body tethering

Correct Answer & Explanation

. Prescription of a TLSO brace for 18 to 23 hours per day

Explanation

Based on the Bracing in Adolescent Idiopathic Scoliosis Trial (BrAIST), bracing significantly decreases the progression of high-risk curves to the surgical threshold. The indication for bracing is a curve between 25 and 45 degrees in a skeletally immature patient (Risser 0-2, premenarchal or <1 year postmenarchal). A TLSO brace worn for a minimum of 18 hours per day demonstrates a dose-dependent success rate.

Question 5293

Topic: 4. Pediatrics

A 3-year-old boy weighing 14 kg is brought to the emergency department after falling from a low bed. Radiographs demonstrate an isolated, closed, spiral midshaft fracture of the right femur with 1.5 cm of shortening. The child is otherwise healthy and the history is consistent with the injury. What is the most appropriate definitive management?

. Flexible intramedullary nailing
. Submuscular locked plating
. Early hip spica casting
. Pavlik harness application
. Skeletal traction followed by cast bracing

Correct Answer & Explanation

. Early hip spica casting

Explanation

For young children (typically ages 6 months to 4-5 years) weighing less than 20 kg (44 lbs) with an isolated diaphyseal femur fracture and less than 2-3 cm of initial shortening, early hip spica casting is the gold standard treatment. Flexible nailing is indicated for older children (ages 5-11) or those weighing over 20 kg. A Pavlik harness is used for infants younger than 6 months.

Question 5294

Topic: 4. Pediatrics

A 3-year-old girl is evaluated for persistent bowing of her lower extremities. A standing AP radiograph reveals bilateral genu varum. Which of the following radiographic parameters is most predictive of progression to infantile Blount disease rather than representing physiologic bowing?

. Metaphyseal-diaphyseal angle greater than 16 degrees
. Metaphyseal-diaphyseal angle less than 10 degrees
. Medial physeal slope of 10 degrees
. Mechanical axis passing through the medial compartment of the knee
. Femoral-tibial angle of 10 degrees varus

Correct Answer & Explanation

. Metaphyseal-diaphyseal angle greater than 16 degrees

Explanation

The metaphyseal-diaphyseal angle (Drennan angle) is a critical radiographic measurement used to distinguish physiologic bowing from infantile Blount disease. An angle greater than 16 degrees is highly predictive of progression to Blount disease, whereas an angle less than 10 degrees suggests physiologic bowing that will likely resolve spontaneously. Angles between 10 and 16 degrees warrant close radiographic observation.

Question 5295

Topic: 4. Pediatrics

An infant is born with prominent anterolateral bowing of the left tibia. Radiographs demonstrate cortical thickening, obliteration of the medullary canal, and sclerosis at the apex of the curve. Which of the following systemic conditions is most strongly associated with this orthopaedic manifestation?

. Osteogenesis imperfecta
. Achondroplasia
. Fibrous dysplasia
. Neurofibromatosis type 1
. Amniotic band syndrome

Correct Answer & Explanation

. Neurofibromatosis type 1

Explanation

Anterolateral bowing of the tibia is the classic precursor to congenital pseudarthrosis of the tibia (CPT). Over 50% of patients with CPT have an underlying diagnosis of Neurofibromatosis type 1 (NF-1). In contrast, posteromedial bowing is typically a benign condition associated with calcaneovalgus foot posture and resolves spontaneously, though it can leave a leg length discrepancy.

Question 5296

Topic: 4. Pediatrics
A 13-year-old girl twists her ankle while playing soccer and is unable to bear weight. Radiographs demonstrate a displaced Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis. This specific fracture pattern occurs because of the asymmetric closure of the distal tibial physis. Which portion of the distal tibial physis is typically the last to close?
. Central
. Anteromedial
. Posteromedial
. Anterolateral
. Posterolateral

Correct Answer & Explanation

. Anterolateral

Explanation

The injury described is a juvenile Tillaux fracture. It occurs because the distal tibial physis closes in an asymmetric, characteristic pattern over approximately an 18-month period. Closure begins centrally, progresses medially, then posteriorly, and the anterolateral portion is the last to close. During this vulnerable period, an external rotation force causes the anterior inferior tibiofibular ligament (AITFL) to avulse the anterolateral epiphysis.

Question 5297

Topic: Pediatric Upper Extremity & Spine

A 5-year-old boy sustains a minimally displaced lateral condyle fracture of the humerus (Milch Type II) that is treated with long-arm cast immobilization. The patient is lost to follow-up and returns 12 years later as a teenager. He has developed a progressive, prominent deformity of the elbow. Which of the following is the most likely long-term neurologic complication associated with nonunion of this specific fracture?

. Anterior interosseous nerve syndrome
. Tardy ulnar nerve palsy
. High radial nerve palsy
. Posterior interosseous nerve syndrome
. Pronator syndrome

Correct Answer & Explanation

. Tardy ulnar nerve palsy

Explanation

Nonunion of a lateral condyle fracture typically results in progressive cubitus valgus due to continued growth of the medial side while the lateral side fails to grow or shifts proximally. Over time, the increasing valgus deformity stretches the ulnar nerve behind the medial epicondyle, classically leading to a tardy ulnar nerve palsy.

Question 5298

Topic: 4. Pediatrics

A newborn is noted to have a shortened right lower extremity with a valgus ankle and absent lateral rays of the foot.

Which of the following knee ligament anomalies is most consistently associated with this condition?

. Absent medial collateral ligament
. Absent anterior cruciate ligament
. Bifid patellar tendon
. Hypertrophic posterior cruciate ligament
. Discoid lateral meniscus

Correct Answer & Explanation

. Absent anterior cruciate ligament

Explanation

Fibular hemimelia is the most common congenital long bone deficiency. It is highly associated with an absent or hypoplastic anterior cruciate ligament (ACL), a ball-and-socket ankle joint, absent lateral rays, and tarsal coalitions.

Question 5299

Topic: Pediatric Lower Extremity

A 3-year-old child with Proximal Focal Femoral Deficiency (PFFD) has a severely shortened femur, an absent femoral head, and no true acetabulum evident on radiographs. According to the Aitken classification, which class does this represent?

. Class A
. Class B
. Class C
. Class D
. Class E

Correct Answer & Explanation

. Class D

Explanation

In the Aitken classification of PFFD: Class A has a femoral head and normal acetabulum with a subtrochanteric defect that eventually ossifies. Class B has a femoral head and normal acetabulum, but the subtrochanteric pseudoarthrosis does not ossify. Class C lacks a femoral head and has severe acetabular dysplasia, but a small tuft of proximal femur exists. Class D is the most severe, with an absent femoral head, absent acetabulum, and a severely shortened femoral shaft with no proximal tuft.

Question 5300

Topic: 4. Pediatrics

A 2-year-old boy presents with an anterolateral bow of the tibia and an impending fracture.

You suspect a systemic condition. Which of the following is the most appropriate initial screening measure for the presumed diagnosis?

. Serum calcium and phosphorus levels
. Genetic testing for a COL1A1 mutation
. Slit-lamp examination for Lisch nodules
. Echocardiogram for aortic root dilation
. Renal ultrasound for Wilms tumor

Correct Answer & Explanation

. Slit-lamp examination for Lisch nodules

Explanation

Anterolateral bowing of the tibia is pathognomonic for congenital pseudoarthrosis of the tibia (CPT), which is strongly associated with Neurofibromatosis type 1 (NF1) in up to 50% of cases. Screening for NF1 includes assessing clinical criteria such as Lisch nodules (iris hamartomas) via a slit-lamp examination.

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