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4. Pediatrics MCQs

Practice Set 314 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 6261

Topic: 4. Pediatrics

An infant is diagnosed with achondroplasia shortly after birth. Which of the following evaluations is most critical to perform during the first year of life to prevent sudden death?

. Echocardiogram for aortic root dilation
. MRI of the craniocervical junction or polysomnography
. Renal ultrasound for polycystic kidneys
. Ultrasound of the hips for DDH
. Full spine radiographs for infantile scoliosis

Correct Answer & Explanation

. MRI of the craniocervical junction or polysomnography

Explanation

Infants with achondroplasia are at high risk for foramen magnum stenosis, which can cause cervicomedullary compression leading to central sleep apnea and sudden infant death. Screening with MRI or sleep studies is critical in the first year.

Question 6262

Topic: 4. Pediatrics
A 3-year-old boy in the 99th percentile for weight presents with bilateral genu varum. Standing AP radiographs show a metaphyseal-diaphyseal angle (Drennan angle) of 18 degrees bilaterally, with medial metaphyseal beaking. What is the most appropriate initial treatment?
. Reassurance and clinical observation for 1 year
. Knee-ankle-foot orthosis (KAFO) bracing
. Proximal tibial valgus osteotomy
. Medial proximal tibial guided growth (eight-plate)
. Lateral proximal tibial epiphysiodesis

Correct Answer & Explanation

. Knee-ankle-foot orthosis (KAFO) bracing

Explanation

The patient has infantile Blount disease (Drennan angle >16 degrees is highly predictive). For children under the age of 4 with Langenskiöld Stage I or II Blount disease, KAFO bracing is the recommended initial non-operative treatment.

Question 6263

Topic: 4. Pediatrics

A 2-year-old toddler falls from a low bed and sustains a closed, isolated, spiral midshaft fracture of the femur with 2 cm of shortening. What is the most appropriate treatment?

. Pavlik harness
. Early spica cast application
. Flexible intramedullary nailing
. Rigid antegrade intramedullary nailing
. Submuscular bridge plating

Correct Answer & Explanation

. Early spica cast application

Explanation

For children aged 6 months to 4-5 years with an isolated femur fracture and <2-3 cm of shortening, early spica casting is the gold standard treatment. Pavlik harnesses are reserved for infants <6 months old.

Question 6264

Topic: Pediatric Hip
Which of the following factors is considered the most significant prognostic indicator for the long-term outcome in a child diagnosed with Legg-Calvé-Perthes disease?
. Age at the onset of the disease
. Gender of the patient
. Patient's body mass index (BMI)
. Bilateral versus unilateral involvement
. Degree of initial hip pain

Correct Answer & Explanation

. Age at the onset of the disease

Explanation

Age at disease onset is the most important prognostic factor in Legg-Calvé-Perthes disease, alongside the lateral pillar classification. Children who develop the disease before age 6 to 8 generally have better remodeling potential and long-term outcomes.

Question 6265

Topic: Pediatric Hip

A 13-year-old boy undergoes in situ single-screw fixation for a stable slipped capital femoral epiphysis (SCFE). At his 6-week follow-up, he complains of severe, constant hip pain and profound loss of hip motion in all planes. Radiographs show a significant reduction in the joint space compared to the immediate post-operative films. What is the most likely diagnosis?

. Avascular necrosis of the femoral head
. Chondrolysis
. Undiagnosed septic arthritis
. Hardware failure
. Contralateral SCFE

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a devastating complication of SCFE characterized by acute narrowing of the joint space and severe, painful restriction of motion. It is strongly associated with unrecognized pin penetration into the joint space.

Question 6266

Topic: Pediatric Upper Extremity & Spine

A 14-year-old girl with adolescent idiopathic scoliosis (AIS) has a proximal thoracic curve of 20 degrees (bends to 10 degrees), a main thoracic curve of 55 degrees (bends to 20 degrees), and a thoracolumbar curve of 30 degrees (bends to 15 degrees). Based on the Lenke classification system, what is her curve type?

. Type 1 (Main Thoracic)
. Type 2 (Double Thoracic)
. Type 3 (Double Major)
. Type 4 (Triple Major)
. Type 5 (Thoracolumbar/Lumbar)

Correct Answer & Explanation

. Type 1 (Main Thoracic)

Explanation

In the Lenke classification, a Type 1 curve is defined by a structural main thoracic curve, while the proximal thoracic and thoracolumbar curves are non-structural (bend out to <25 degrees). Since only her main thoracic curve is structural, she has a Type 1 curve.

Question 6267

Topic: 4. Pediatrics

A 2-month-old infant is diagnosed with congenital muscular torticollis affecting the right sternocleidomastoid (SCM) muscle. Which of the following best describes the typical posturing of the infant's head?

. Head tilted to the right and rotated to the right
. Head tilted to the left and rotated to the left
. Head tilted to the right and rotated to the left
. Head tilted to the left and rotated to the right
. Head held in rigid neutral with no rotation

Correct Answer & Explanation

. Head tilted to the right and rotated to the left

Explanation

In right-sided congenital muscular torticollis, the tight right SCM muscle causes the head to tilt toward the affected side (right) and rotate toward the contralateral side (left).

Question 6268

Topic: Pediatric Hip

An 8-year-old boy with Legg-Calve-Perthes disease presents for follow-up. Radiographs reveal a V-shaped radiolucent defect in the lateral portion of the proximal femoral epiphysis. What is the name of this specific radiographic finding, and what does it indicate?

. Gage sign, indicating a "head at risk" for poor outcome
. Trethowan sign, indicating a stable lesion
. Klein's line, indicating impending physeal slip
. Hilgenreiner's line, indicating severe lateral subluxation
. Perkins sign, indicating early re-ossification

Correct Answer & Explanation

. Gage sign, indicating a "head at risk" for poor outcome

Explanation

The Gage sign is a V-shaped radiolucency in the lateral epiphysis and adjacent metaphysis. It is one of Catterall's "head at risk" signs in Legg-Calve-Perthes disease, which correlate with a poorer prognosis and progressive deformity.

Question 6269

Topic: Pediatric Hip

An 18-month-old girl undergoes closed reduction for developmental dysplasia of the hip (DDH). Intraoperative arthrography reveals an hourglass-shaped capsular constriction preventing the femoral head from seating concentrically in the acetabulum. Which anatomical structure is responsible for creating this extra-articular constriction?

. Transverse acetabular ligament
. Iliopsoas tendon
. Ligamentum teres
. Inverted limbus
. Reflected head of the rectus femoris

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

The iliopsoas tendon crosses the anterior aspect of the hip capsule, creating an hourglass capsular constriction that can physically block concentric closed reduction in DDH. The transverse ligament, ligamentum teres, and limbus are intra-articular blocks.

Question 6270

Topic: Pediatric Lower Extremity

An infant with idiopathic clubfoot is undergoing the first stage of the Ponseti casting method. Which manipulative maneuver is required to correctly address the initial component of the deformity?

. Supination of the forefoot with elevation of the first ray
. Pronation of the forefoot with plantarflexion of the first ray
. Dorsiflexion of the midfoot against a fixed talus
. External rotation of the calcaneus
. Eversion of the hindfoot

Correct Answer & Explanation

. Supination of the forefoot with elevation of the first ray

Explanation

The first step in the Ponseti method is correcting the cavus deformity by elevating the first ray to supinate the forefoot. This aligns the forefoot with the hindfoot, preventing the creation of a midfoot break.

Question 6271

Topic: Pediatric Hip
A 14-year-old boy underwent in situ single-screw fixation for an unstable slipped capital femoral epiphysis (SCFE). Six months later, he complains of severe hip stiffness. Radiographs show a marked reduction in the joint space to <3 mm without femoral head collapse. What is the most likely diagnosis?
. Avascular necrosis (AVN)
. Chondrolysis
. Septic arthritis
. Femoroacetabular impingement
. Implant failure

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis presents with acute joint space narrowing and severe stiffness following a SCFE, often associated with unrecognized articular pin penetration. Unlike AVN, chondrolysis does not typically involve structural collapse of the femoral head.

Question 6272

Topic: 4. Pediatrics

A 2-year-old obese girl presents with bilateral progressive genu varum. Radiographs reveal metaphyseal beaking and a Langenskiold stage II classification. What is the most appropriate initial management?

. Observation and reassurance
. Knee-ankle-foot orthoses (KAFO)
. Proximal tibial valgus osteotomy
. Guided growth via lateral hemiepiphysiodesis
. Physeal bar resection

Correct Answer & Explanation

. Knee-ankle-foot orthoses (KAFO)

Explanation

In infantile Blount disease (children <3 years old) with Langenskiold stage I or II, bracing with KAFOs is the initial treatment of choice. Surgical intervention is reserved for older children, failed bracing, or higher Langenskiold stages.

Question 6273

Topic: 4. Pediatrics
A 14-year-old girl sustains a Salter-Harris III fracture of the anterolateral distal tibia. Which specific biomechanical mechanism is responsible for this fracture pattern?
. Supination and inversion of the foot
. External rotation of the foot causing avulsion via the AITFL
. Direct axial loading on a plantarflexed ankle
. Pronation and abduction of the foot
. Plantarflexion and internal rotation

Correct Answer & Explanation

. External rotation of the foot causing avulsion via the AITFL

Explanation

A juvenile Tillaux fracture is a Salter-Harris III injury caused by external rotation of the foot, which tensions the anterior inferior tibiofibular ligament (AITFL). It occurs precisely during the period when the medial physis has closed but the lateral physis remains open.

Question 6274

Topic: 4. Pediatrics

A 3-year-old boy presents with anterolateral bowing of his left tibia and a radiographically confirmed pseudarthrosis. Which systemic disorder is most strongly associated with this orthopaedic condition?

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

Correct Answer & Explanation

. Neurofibromatosis type 1

Explanation

Anterolateral bowing of the tibia with congenital pseudarthrosis (CPT) is highly associated with Neurofibromatosis type 1 (NF1). Management is notoriously difficult and typically requires excision of the hamartomatous tissue with rigid fixation.

Question 6275

Topic: 4. Pediatrics

A 2-month-old infant is brought to the clinic holding his head persistently tilted to the right and rotated to the left. A firm, painless mass is palpated in the right side of the neck. Because this condition is part of the "packaging disorders," what other screening is unequivocally indicated?

. Renal ultrasound for congenital anomalies
. Radiographs of the cervical spine for Klippel-Feil syndrome
. Clinical and ultrasound screening for developmental dysplasia of the hip
. Echocardiogram for associated cardiac defects
. MRI of the brain for Chiari malformation

Correct Answer & Explanation

. Clinical and ultrasound screening for developmental dysplasia of the hip

Explanation

Congenital muscular torticollis is caused by unilateral contracture of the sternocleidomastoid muscle. It is highly associated with developmental dysplasia of the hip (up to 20%), making routine hip screening mandatory.

Question 6276

Topic: 4. Pediatrics
A 13-year-old girl sustains an ankle injury. Radiographs demonstrate a Salter-Harris III fracture of the distal tibial epiphysis, isolated to the anterolateral quadrant. This specific fracture pattern is dictated by the physiological closure sequence of the distal tibial physis. Which portion of the distal tibial physis is the last to close?
. Central
. Anteromedial
. Posteromedial
. Posterolateral
. Anterolateral

Correct Answer & Explanation

. Anterolateral

Explanation

The distal tibial physis closes in a predictable sequence: central, anteromedial, posteromedial, and finally anterolateral. Because the anterolateral physis remains open longest, it is selectively vulnerable to an avulsion fracture (Tillaux fracture) via the anterior inferior tibiofibular ligament.

Question 6277

Topic: 4. Pediatrics

A 4-year-old boy is evaluated for a painless waddling gait. Pelvic radiographs demonstrate a unilateral decreased femoral neck-shaft angle with a vertically oriented proximal femoral physis. What specific radiographic parameter is the strongest indication for a valgus-producing proximal femoral osteotomy in this patient?

. Femoral neck-shaft angle < 110 degrees
. Hilgenreiner-epiphyseal angle > 60 degrees
. Center-edge angle < 20 degrees
. Reimers migration index > 33%
. Southwick angle > 50 degrees

Correct Answer & Explanation

. Hilgenreiner-epiphyseal angle > 60 degrees

Explanation

In developmental coxa vara, a Hilgenreiner-epiphyseal angle (HEA) greater than 60 degrees indicates a high risk of progression and pseudarthrosis, serving as a strong indication for a subtrochanteric valgus osteotomy. An HEA of less than 45 degrees generally portends spontaneous resolution.

Question 6278

Topic: Pediatric Hip

A 9-year-old boy with known Legg-Calve-Perthes disease presents with increasing hip pain and decreased range of motion. A dynamic hip arthrogram reveals hinge abduction, demonstrating the anterolateral femoral head impinging on the acetabular rim. What is the most appropriate surgical management?

. Adductor tenotomy and Petrie casting
. In situ pinning of the capital femoral epiphysis
. Varus derotational osteotomy of the proximal femur
. Valgus extension osteotomy of the proximal femur
. Core decompression of the femoral head

Correct Answer & Explanation

. Valgus extension osteotomy of the proximal femur

Explanation

Hinge abduction occurs when the enlarged, extruded anterolateral femoral head impinges against the lateral acetabular rim during abduction. A valgus-extension proximal femoral osteotomy is indicated to redirect the impinging segment away from the rim, improving congruency and relieving pain.

Question 6279

Topic: 4. Pediatrics

A 7-year-old boy presents for follow-up 1 year after non-operative treatment of a Gartland Type II supracondylar humerus fracture. He has full range of motion but complains of an unsightly "gunstock" deformity of the elbow. What is the primary pathophysiological cause of this deformity?

. Asymmetric overgrowth of the lateral humeral condyle
. Premature growth arrest of the medial distal humeral physis
. Malreduction leaving residual internal rotation and medial column collapse
. Heterotopic ossification of the brachialis muscle
. Undiagnosed secondary lateral condyle fracture

Correct Answer & Explanation

. Malreduction leaving residual internal rotation and medial column collapse

Explanation

Cubitus varus (gunstock deformity) is the most common long-term complication of a pediatric supracondylar humerus fracture. It is predominantly caused by mechanical malreduction characterized by medial column comminution/collapse and residual internal rotation, rather than physeal growth arrest.

Question 6280

Topic: 4. Pediatrics

A 4-year-old girl with a BMI in the 99th percentile presents with progressive bilateral genu varum. Clinical exam shows a prominent lateral thrust during gait. Radiographs exhibit a sharp metaphyseal beak medially and a metaphyseal-diaphyseal angle of 18 degrees. What is the most appropriate management?

. Reassurance and observation for spontaneous resolution
. Full-time wear of knee-ankle-foot orthoses (KAFOs)
. High-dose Vitamin D and calcium supplementation
. Bilateral proximal tibial and fibular valgus osteotomies
. Bilateral guided growth (8-Plates) on the lateral proximal tibia

Correct Answer & Explanation

. Bilateral proximal tibial and fibular valgus osteotomies

Explanation

This child has infantile Blount's disease. Because she is over the age of 3 and has advanced radiographic changes (high metaphyseal-diaphyseal angle and sharp medial beak), orthotic management will likely fail; thus, surgical realignment via proximal tibial valgus osteotomies is definitively indicated to prevent joint destruction.

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