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4. Pediatrics MCQs

Practice Set 171 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 3401

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a completely displaced, extension-type supracondylar humerus fracture. On arrival, the hand is pink and well-perfused, but the radial pulse is absent. What is the most appropriate next step in management?

. Immediate exploration of the brachial artery
. Urgent CT angiography
. Closed reduction and percutaneous pinning, followed by observation if perfusion remains intact
. Open reduction and internal fixation with prophylactic fasciotomies
. Application of a hyperflexion cast

Correct Answer & Explanation

. Closed reduction and percutaneous pinning, followed by observation if perfusion remains intact

Explanation

For a 'pink, pulseless' hand associated with a supracondylar humerus fracture, the initial treatment is urgent closed reduction and percutaneous pinning. If the hand remains well-perfused after pinning, vascular exploration is not indicated, and the patient can be closely observed.

Question 3402

Topic: 4. Pediatrics
A 4-year-old obese boy presents with bilateral progressive bowing of the legs. Radiographs demonstrate a metaphyseal-diaphyseal angle of 18 degrees and profound depression of the medial proximal tibial physis (Langenskiold stage III). What is the recommended treatment?
. Observation and vitamin D supplementation
. Use of knee-ankle-foot orthoses (KAFOs)
. Medial hemiepiphysiodesis of the proximal tibia
. Proximal tibial valgus-producing osteotomy
. Lateral distal femoral osteotomy

Correct Answer & Explanation

. Proximal tibial valgus-producing osteotomy

Explanation

Infantile Blount disease in a child older than 3 years with advanced changes (Langenskiold stage III) and a high metaphyseal-diaphyseal angle (>16 degrees) rarely responds to bracing. A proximal tibial valgus-producing and derotational osteotomy is indicated to correct the deformity.

Question 3403

Topic: 4. Pediatrics

A 2-year-old girl is evaluated for recurrent fractures following minimal trauma. Clinical examination reveals blue sclerae and dentinogenesis imperfecta. A defect in which of the following genes is most likely responsible?

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

Correct Answer & Explanation

. COL1A1 or COL1A2

Explanation

The patient's clinical presentation is classic for Osteogenesis Imperfecta (OI). OI is most commonly caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, which encode type I collagen.

Question 3404

Topic: Pediatric Hip

A 7-year-old boy has been limping for 6 months and is diagnosed with Legg-Calve-Perthes disease. Radiographs show fragmentation of the femoral head. Which of the following radiographic findings represents the poorest prognostic factor?

. Coxa magna
. Intact lateral pillar
. Lateral subluxation of the femoral head
. Sclerosis of the epiphysis
. Widening of the medial joint space

Correct Answer & Explanation

. Lateral subluxation of the femoral head

Explanation

Lateral subluxation (extrusion) of the femoral head is a major "head at risk" sign and a poor prognostic factor in Perthes disease. It can lead to hinge abduction, resulting in severe deformity and early osteoarthritis.

Question 3405

Topic: 4. Pediatrics

Congenital pseudarthrosis of the tibia (CPT) is most frequently associated with which of the following systemic conditions?

. Tuberous sclerosis
. Neurofibromatosis type 1
. Osteogenesis imperfecta
. Fibrous dysplasia
. Achondroplasia

Correct Answer & Explanation

. Neurofibromatosis type 1

Explanation

Congenital pseudarthrosis of the tibia (CPT) is strongly associated with Neurofibromatosis type 1 (NF1), occurring in approximately 50% of patients with CPT. It typically presents as anterolateral bowing of the tibia that progresses to fracture and nonunion.

Question 3406

Topic: 4. Pediatrics
A 14-year-old girl presents with ankle pain after a twisting injury. Radiographs show a Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis. This injury (Tillaux fracture) is caused by avulsion from which of the following structures?
. Anterior talofibular ligament
. Calcaneofibular ligament
. Deltoid ligament
. Anterior inferior tibiofibular ligament (AITFL)
. Posterior inferior tibiofibular ligament (PITFL)

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament (AITFL)

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It occurs due to an external rotation force causing the anterior inferior tibiofibular ligament (AITFL) to avulse the anterolateral epiphysis, which is the last portion of the physis to close.

Question 3407

Topic: Pediatric Hip

A 12-year-old obese boy presents to the emergency department with severe right groin pain and an inability to bear weight on his right leg after a minor fall. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). He undergoes urgent in situ pinning. Which of the following complications is most highly associated with this patient's specific type of presentation?

. Avascular necrosis (AVN)
. Chondrolysis
. Subtrochanteric femur fracture
. Deep space infection
. Implant failure

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

This patient has an unstable SCFE, defined by the inability to bear weight even with crutches. Unstable SCFE has a significantly higher rate of avascular necrosis (up to 20-50%) compared to stable SCFE, regardless of the treatment method used.

Question 3408

Topic: Pediatric Hip

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During the follow-up visit, the parents report that the infant is no longer actively extending the knee on the treated side. On examination, there is decreased spontaneous movement of the quadriceps. What is the most appropriate next step in management?

. Loosen the anterior straps of the harness
. Loosen the posterior straps of the harness
. Immediately abandon the harness and switch to a spica cast
. Order an urgent MRI of the lumbar spine
. Continue the current settings and observe for another 2 weeks

Correct Answer & Explanation

. Loosen the anterior straps of the harness

Explanation

The infant presents with a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The appropriate management is to loosen the anterior straps to decrease hip flexion, which usually leads to spontaneous resolution of the palsy.

Question 3409

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvรฉ-Perthes disease (LCPD). Which of the following factors at the time of presentation is considered the most significant predictor of a poor long-term radiographic outcome?
. Age of onset greater than 8 years
. Male gender
. Herring Lateral Pillar group A classification
. Loss of internal rotation less than 15 degrees
. Involvement of the medial aspect of the epiphysis

Correct Answer & Explanation

. Age of onset greater than 8 years

Explanation

Age at onset is a critical prognostic factor in LCPD; children older than 8 years generally have a worse prognosis and a higher risk of developing residual deformity and secondary osteoarthritis. The Herring Lateral Pillar classification is also highly prognostic, but Group A represents a good outcome.

Question 3410

Topic: Pediatric Upper Extremity & Spine
A 5-year-old girl falls from monkey bars and sustains a widely displaced, extension-type Gartland III supracondylar humerus fracture. On initial evaluation, the hand is pink and warm, but the radial pulse is not palpable. What is the most appropriate initial management?
. Closed reduction and percutaneous pinning, followed by reassessment of the pulse
. Immediate open exploration of the brachial artery
. Urgent CT angiography of the upper extremity
. Prophylactic forearm fasciotomies
. Observation in a long arm cast for 24 hours

Correct Answer & Explanation

. Closed reduction and percutaneous pinning, followed by reassessment of the pulse

Explanation

A "pulseless, pink" hand in the setting of a displaced supracondylar fracture should be managed with prompt closed reduction and percutaneous pinning (CRPP). Routine exploration is not required unless the hand becomes poorly perfused (white) after reduction.

Question 3411

Topic: Pediatric Lower Extremity

A 2-year-old child with a history of idiopathic clubfoot successfully treated with the Ponseti method presents with a dynamic supination deformity during the swing phase of gait. Passive range of motion is full, and the foot is completely correctable. What is the most appropriate surgical intervention?

. Tibialis anterior tendon transfer to the lateral cuneiform
. Achilles tendon lengthening alone
. Complete posteromedial release
. Talectomy
. Split tibialis posterior tendon transfer

Correct Answer & Explanation

. Tibialis anterior tendon transfer to the lateral cuneiform

Explanation

Relapsed clubfoot presenting as dynamic supination in a toddler with a flexible foot is best treated with a full transfer of the tibialis anterior tendon to the lateral cuneiform. This balances the foot by removing the supinating force and converting it to a dorsiflexing/everting force.

Question 3412

Topic: 4. Pediatrics

A 30-month-old obese child presents with bilateral severe genu varum and a noticeable lateral thrust during gait. Radiographs show medial beaking of the proximal tibia. Which radiographic parameter most reliably differentiates infantile Blount disease from physiologic bowing?

. Metaphyseal-diaphyseal angle greater than 16 degrees
. Metaphyseal-diaphyseal angle less than 10 degrees
. Tibiofemoral angle greater than 15 degrees varus
. Mechanical axis passing through the medial compartment
. Symmetrical involvement of both knees

Correct Answer & Explanation

. Metaphyseal-diaphyseal angle greater than 16 degrees

Explanation

A metaphyseal-diaphyseal angle (Drennan's angle) of greater than 16 degrees on an AP radiograph is highly indicative of infantile Blount disease rather than physiologic genu varum. Angles less than 10 degrees usually resolve spontaneously.

Question 3413

Topic: 4. Pediatrics

A 5-year-old girl is evaluated for multiple long bone fractures following minimal trauma. Clinical examination reveals blue sclerae and opalescent, abnormally worn teeth. Mutations in which of the following genes are the most common cause of her condition?

. COL1A1 and COL1A2
. COL2A1
. FGFR3
. COMP
. RUNX2

Correct Answer & Explanation

. COL1A1 and COL1A2

Explanation

The patient has osteogenesis imperfecta (OI), classically associated with blue sclerae and dentinogenesis imperfecta. OI is most commonly caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, which encode type I collagen.

Question 3414

Topic: 4. Pediatrics

A 6-year-old boy is evaluated for an acute fracture through the growth plate of a major long bone. Which of the following physeal fracture locations carries the highest intrinsic incidence of premature physeal closure, even in the setting of non-displaced Salter-Harris I and II patterns?

. Distal femur
. Distal radius
. Proximal humerus
. Distal tibia
. Proximal femur

Correct Answer & Explanation

. Distal femur

Explanation

The distal femoral physis has a unique undulating shape, making it highly susceptible to crushing forces during injury. Consequently, even low-grade Salter-Harris fractures (I and II) here have an unexpectedly high rate of premature growth arrest (up to 40-50%).

Question 3415

Topic: Pediatric Hip

Figure 37 shows a radiograph of a 13-year-old presenting with hip pain.

To assess for the condition seen, a line is drawn along the superior aspect of the femoral neck. In a normal hip, this line intersects the lateral aspect of the epiphysis. What is the eponymous sign when this line fails to intersect the epiphysis?

. Trethowan sign
. Crescent sign
. Sagging rope sign
. Throckmorton sign
. Hilgenreiner's sign

Correct Answer & Explanation

. Trethowan sign

Explanation

The line described is Klein's line. In slipped capital femoral epiphysis (SCFE), Klein's line passes completely superior to the epiphysis rather than intersecting it; this finding is known as the Trethowan sign.

Question 3416

Topic: 4. Pediatrics

A newborn is evaluated in the nursery for a significantly shortened left lower extremity. The hip is maintained in a flexed, abducted, and externally rotated position. Radiographs reveal a severe deficiency of the proximal femur. Which of the following congenital anomalies is most commonly associated with this presentation?

. Fibular hemimelia
. Tibial hemimelia
. Radial clubhand
. Congenital vertical talus
. Developmental dysplasia of the hip

Correct Answer & Explanation

. Fibular hemimelia

Explanation

The clinical presentation describes proximal femoral focal deficiency (PFFD). Fibular hemimelia is the most common associated longitudinal deficiency seen in patients with PFFD, occurring in approximately 50% to 70% of cases.

Question 3417

Topic: 4. Pediatrics

A 6-year-old child with spastic quadriplegic cerebral palsy is found to have a Reimer's migration percentage of 45% on a screening AP pelvis radiograph. Spasticity in which specific muscle groups is the primary deforming force leading to hip subluxation in this patient population?

. Hip adductors and flexors
. Hip abductors and extensors
. Hip adductors and external rotators
. Hip abductors and internal rotators
. Hamstrings and quadriceps

Correct Answer & Explanation

. Hip adductors and flexors

Explanation

In cerebral palsy, progressive hip subluxation and dislocation are driven by the muscle imbalance primarily caused by spasticity and contracture of the hip adductors and hip flexors (iliopsoas). This forces the hip into adduction and flexion, levering the femoral head out of the acetabulum.

Question 3418

Topic: Pediatric Hip

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, it is noted that the harness is adjusted with excessive hip flexion. This specific malposition is most associated with which of the following complications?

. Femoral nerve palsy
. Avascular necrosis of the femoral head
. Obturator nerve palsy
. Inferior hip dislocation
. Acetabular dysplasia

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Excessive hip flexion in a Pavlik harness can cause impingement leading to a femoral nerve palsy. In contrast, excessive abduction is classically associated with avascular necrosis of the femoral head.

Question 3419

Topic: Pediatric Hip

A 13-year-old obese boy presents with a stable slipped capital femoral epiphysis (SCFE) of the left hip. What is the most established primary indication for prophylactic pinning of the asymptomatic contralateral hip?

. Modified Southwick angle greater than 60 degrees
. Age less than 10 years at presentation or an underlying endocrinopathy
. Body mass index (BMI) greater than the 95th percentile
. Unstable presentation of the index slip
. Triradiate cartilage closure on presentation

Correct Answer & Explanation

. Age less than 10 years at presentation or an underlying endocrinopathy

Explanation

Prophylactic pinning of the contralateral hip is generally recommended for patients younger than 10 years or those with underlying endocrine disorders (e.g., hypothyroidism). These patients have a significantly higher risk of developing bilateral involvement.

Question 3420

Topic: Pediatric Hip

An 8-year-old boy with Legg-Calve-Perthes disease presents with hip pain and a limp. Radiographs reveal greater than 50% maintenance of the lateral pillar height (Herring B). According to the Herring lateral pillar classification, what is the most appropriate management?

. Symptomatic management and observation only
. Pelvic or femoral osteotomy for surgical containment
. Core decompression of the femoral head
. Epiphysiodesis of the greater trochanter
. Application of an A-frame abduction orthosis

Correct Answer & Explanation

. Pelvic or femoral osteotomy for surgical containment

Explanation

For patients 8 years and older with Herring group B or B/C border Perthes disease, surgical containment (pelvic or femoral osteotomy) is indicated. This approach yields better radiographic and clinical outcomes compared to nonoperative treatment in this older age group.

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