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4. Pediatrics MCQs

Practice Set 156 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 3101

Topic: Pediatric Hip

An 9-year-old boy presents with a 5-month history of a painless limp and right hip stiffness. Radiographs demonstrate Legg-Calvé-Perthes disease in the fragmentation stage.

Which of the following factors is the most reliable predictor of a poor long-term radiographic and clinical outcome, often necessitating surgical containment?

. Age of onset greater than 8 years
. Limitation of hip internal rotation to 10 degrees
. Presence of a subchondral fracture line (Crescent sign) involving 20% of the epiphysis
. Increased medial joint space on the anteroposterior radiograph
. Herring Lateral Pillar Class A

Correct Answer & Explanation

. Age of onset greater than 8 years

Explanation

Age at disease onset is one of the most critical prognostic factors in Legg-Calvé-Perthes disease. Children who develop the disease after the age of 8 years have less potential for remodeling and typically experience worse long-term outcomes (higher risk of severe residual deformity and early-onset osteoarthritis). According to the multicenter prospective studies by Herring et al., patients older than 8 years at onset who have Lateral Pillar B or B/C border hips benefit significantly from surgical containment (e.g., proximal femoral varus osteotomy or pelvic osteotomy) compared to non-operative treatment. Lateral Pillar Class A has a universally good prognosis regardless of age.

Question 3102

Topic: Pediatric Upper Extremity & Spine

A 5-year-old boy falls from monkey bars and presents to the emergency department. Radiographs reveal a completely displaced, extension-type supracondylar humerus fracture. On examination, his hand is pink and warm, but the radial pulse is not palpable. Capillary refill is brisk (< 2 seconds). He is unable to make an 'OK' sign, but finger extension is intact. What is the most appropriate initial management?

. Emergent open reduction and brachial artery exploration
. Urgent closed reduction and percutaneous pinning, followed by observation of perfusion
. CT angiography of the upper extremity
. Application of a long arm cast in 90 degrees of flexion
. Closed reduction and immediate vascular surgery consultation for bypass

Correct Answer & Explanation

. Urgent closed reduction and percutaneous pinning, followed by observation of perfusion

Explanation

The clinical presentation is a 'pulseless, pink hand' associated with a completely displaced supracondylar humerus fracture, along with an anterior interosseous nerve (AIN) palsy (unable to make an OK sign). The initial management for a well-perfused, pulseless hand in this setting is urgent closed reduction and percutaneous pinning (CRPP). Often, the pulse returns following reduction as the kinked or compressed brachial artery is relieved. If the hand remains pink and well-perfused with brisk capillary refill after stabilization, continued observation is appropriate without immediate vascular exploration. Vascular exploration is indicated if the hand is poorly perfused (pale, cold, pulseless) before reduction and remains so after reduction, or if it becomes poorly perfused after reduction.

Question 3103

Topic: Pediatric Hip

A 12-year-old boy weighing 95 kg presents to the emergency department with severe left hip pain and inability to bear weight after tripping two days ago. He reports mild, intermittent left knee pain over the preceding month. Radiographs demonstrate a severe left slipped capital femoral epiphysis (SCFE). Based on the Loder classification, what is the most significant risk factor for developing avascular necrosis (AVN) in this patient?

. The severity of the slip angle exceeding 50 degrees
. The prolonged duration of his prodromal knee pain
. The clinical inability to bear weight with or without crutches
. The use of a single-screw construct rather than double-screw fixation
. The delay in surgical intervention beyond 12 hours from the injury

Correct Answer & Explanation

. The clinical inability to bear weight with or without crutches

Explanation

The Loder classification categorizes Slipped Capital Femoral Epiphysis (SCFE) into stable and unstable based on the patient's clinical ability to bear weight (with or without crutches). An unstable SCFE (inability to bear weight) is associated with a much higher rate of avascular necrosis (AVN), historically reported as up to 47%, compared to nearly 0% in stable SCFE. Thus, instability is the most profound prognostic factor for AVN in these patients.

Question 3104

Topic: 4. Pediatrics

A 14-year-old girl sustains an ankle injury while playing soccer. Radiographs show a displaced Salter-Harris III fracture of the anterolateral distal tibia. Which of the following best describes the biomechanical mechanism and developmental etiology of this specific fracture?

. Avulsion by the anterior inferior tibiofibular ligament during external rotation, with the anterolateral physis closing last
. Avulsion by the anterior talofibular ligament during inversion, with the medial physis closing last
. Axial loading leading to compression of the anterolateral physis, which closes first
. Avulsion by the deltoid ligament during eversion, with the anteromedial physis closing last
. Plantarflexion and internal rotation causing a shear fracture of the entire distal tibial physis

Correct Answer & Explanation

. Avulsion by the anterior inferior tibiofibular ligament during external rotation, with the anterolateral physis closing last

Explanation

This is a juvenile Tillaux fracture, which is a Salter-Harris III fracture of the anterolateral distal tibia. It typically occurs in adolescents around 12 to 14 years of age. The distal tibial physis closes in an asymmetric, predictable pattern: central, then anteromedial, then posteromedial, and finally lateral (anterolateral). Because the anterolateral physis is the last to close, it is susceptible to avulsion forces. The mechanism is external rotation of the foot within the mortise, causing the anterior inferior tibiofibular ligament (AITFL) to avulse the anterolateral epiphyseal fragment.

Question 3105

Topic: Pediatric Hip

An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. AP and frog-leg lateral pelvis radiographs show the hip is currently in the fragmentation stage. According to the Herring lateral pillar classification, which of the following radiographic features is the most critical for determining the long-term prognosis?

. The extent of the subchondral fracture (crescent sign)
. The degree of height loss in the lateral portion of the capital femoral epiphysis
. The presence and size of metaphyseal cysts
. The degree of extrusion of the femoral head lateral to the margin of the acetabulum
. The involvement and collapse of the medial column of the femoral head

Correct Answer & Explanation

. The degree of height loss in the lateral portion of the capital femoral epiphysis

Explanation

The Herring Lateral Pillar Classification is evaluated on the AP radiograph during the fragmentation stage of Legg-Calvé-Perthes disease and is widely considered the most reliable prognostic indicator for future sphericity of the femoral head. It specifically evaluates the degree of height loss in the lateral pillar (the lateral 15% to 30% of the femoral head). Group A has no height loss, Group B has less than 50% height loss, and Group C has greater than 50% height loss (which carries the worst prognosis).

Question 3106

Topic: Pediatric Hip

An 18-month-old girl presents with a painless limp. Examination demonstrates a positive Trendelenburg sign on the left and a leg length discrepancy. Pelvic radiographs confirm a completely dislocated left hip with an acetabular index of 42 degrees and a broken Shenton's line.

What is the most appropriate definitive management?

. Application of a Pavlik harness for 6 weeks
. Closed reduction and spica casting
. Arthroscopic reduction and labral repair
. Open reduction, pelvic osteotomy, and femoral shortening osteotomy
. Observation until skeletal maturity followed by total hip arthroplasty

Correct Answer & Explanation

. Open reduction, pelvic osteotomy, and femoral shortening osteotomy

Explanation

In a child of ambulatory age (typically > 18 months) presenting with a missed or late-diagnosed Developmental Dysplasia of the Hip (DDH) that is completely dislocated, secondary adaptive changes such as severe soft tissue contractures, acetabular dysplasia, and excessive femoral anteversion/coxa valga have occurred. An open reduction is typically necessary to clear obstacles (e.g., inverted limbus, hypertrophied pulvinar, intact transverse acetabular ligament). A femoral shortening osteotomy is frequently performed to decompress the joint, allowing reduction without excessive pressure on the cartilage, thereby minimizing the risk of avascular necrosis (AVN). A concurrent pelvic osteotomy (e.g., Salter or Pemberton) is necessary to correct the severe acetabular dysplasia (acetabular index of 42 degrees).

Question 3107

Topic: 4. Pediatrics

A 7-year-old girl with spastic quadriplegic cerebral palsy (GMFCS Level V) is evaluated during routine hip surveillance. Her parents report increasing difficulty with perineal hygiene and positioning her in her wheelchair. An AP pelvis radiograph demonstrates a right hip Reimers migration percentage of 65% with significant coxa valga and an intact acetabular teardrop.

What is the recommended surgical management to provide a stable, concentric hip?

. Isolated adductor and iliopsoas tenotomies
. Open reduction and capsulorrhaphy alone
. Varus derotational osteotomy (VDRO) of the proximal femur with a pelvic osteotomy
. Proximal femoral resection arthroplasty (Castle procedure)
. Total hip arthroplasty

Correct Answer & Explanation

. Varus derotational osteotomy (VDRO) of the proximal femur with a pelvic osteotomy

Explanation

Children with severe cerebral palsy (GMFCS IV and V) are at high risk for progressive hip displacement due to spasticity and muscle imbalance, leading to coxa valga and secondary acetabular dysplasia. A Reimers migration percentage (MP) greater than 50% generally indicates the need for comprehensive bony reconstruction. The standard of care to achieve a stable, concentric, and pain-free hip in this scenario is a one-stage reconstruction involving a varus derotational osteotomy (VDRO) of the proximal femur to correct the coxa valga and anteversion, combined with a pelvic osteotomy (e.g., Dega, San Diego, or Pemberton) to address acetabular dysplasia, often alongside soft-tissue releases. Salvage procedures (like resection arthroplasty) are reserved for painful, chronically dislocated hips with severe degenerative changes that cannot be reconstructed.

Question 3108

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a completely displaced Gartland type III supracondylar humerus fracture. He undergoes prompt closed reduction and percutaneous pinning. Postoperatively, the radial pulse remains unpalpable, but the hand is warm with a brisk capillary refill of less than 2 seconds. Pulse oximetry on the index finger shows a strong waveform and 99% oxygen saturation.

What is the most appropriate next step in management?

. Immediate exploration of the brachial artery
. CT angiography of the upper extremity
. Observation and hospital admission for monitoring
. Remove the percutaneous pins and convert to an open reduction
. Stellate ganglion block to relieve arterial spasm

Correct Answer & Explanation

. Observation and hospital admission for monitoring

Explanation

In the setting of a supracondylar humerus fracture with a "pulseless but pink" hand following satisfactory closed reduction and pinning, the standard of care is observation and admission for serial clinical examinations. The collateral circulation in pediatric patients is typically robust enough to maintain adequate perfusion even if the brachial artery is in spasm, contused, or tethered. Arterial exploration is strictly indicated if the hand is persistently ischemic (white, cool, lack of capillary refill) after reduction.

Question 3109

Topic: Pediatric Hip

A 2.5-year-old girl is brought in for a persistent, painless limp. Physical examination reveals asymmetric thigh folds, limited abduction of the left hip, and a positive Galeazzi sign on the left. Radiographs confirm a dislocated left hip with an acetabular index of 42 degrees and a delayed ossification center of the femoral head.

What is the most appropriate surgical management for this patient?

. Application of a Pavlik harness
. Closed reduction and spica casting
. Open reduction, pelvic osteotomy, and spica casting
. Observation until age 4 to allow for maximum spontaneous acetabular remodeling
. Varus derotational osteotomy (VDRO) alone

Correct Answer & Explanation

. Open reduction, pelvic osteotomy, and spica casting

Explanation

By the age of 2.5 years, conservative measures such as a Pavlik harness or closed reduction are inappropriate due to the severity of adaptive changes and capsular constriction. This patient has Developmental Dysplasia of the Hip (DDH) with significant acetabular dysplasia (acetabular index > 30 degrees). The standard of care for a walking child older than 18-24 months is an open reduction combined with a pelvic osteotomy (e.g., Salter or Pemberton) to correct the dysplasia and provide anterior/lateral coverage, often accompanied by a femoral shortening osteotomy depending on the degree of proximal migration.

Question 3110

Topic: Pediatric Hip

A 12-year-old boy is diagnosed with a stable slipped capital femoral epiphysis (SCFE) of the left hip. He denies any right hip pain. Which of the following is considered the most widely accepted absolute indication for prophylactic in-situ pinning of his contralateral asymptomatic right hip?

. Patient age greater than 14 years at presentation
. Presence of an underlying endocrine disorder (e.g., hypothyroidism)
. Male gender
. Patient BMI > 95th percentile for age
. Radiographic evidence of a physeal angle greater than 30 degrees

Correct Answer & Explanation

. Presence of an underlying endocrine disorder (e.g., hypothyroidism)

Explanation

While prophylactic pinning of the contralateral hip in SCFE is controversial for idiopathic cases, there is broad consensus that patients with atypical SCFE—specifically those with underlying endocrine disorders (e.g., hypothyroidism, panhypopituitarism, renal osteodystrophy) or prior radiation therapy—should undergo prophylactic contralateral pinning. These patients have a significantly higher risk of bilateral involvement (up to 100% in some endocrine cohorts) compared to those with idiopathic SCFE.

Question 3111

Topic: Pediatric Lower Extremity

A 4-year-old boy who was successfully treated for an idiopathic clubfoot with the Ponseti method presents with a relapse. His parents report that he walks on the outside of his foot. On examination, he demonstrates dynamic supination of the foot during the swing phase of gait. However, his passive ankle dorsiflexion is 15 degrees with the knee extended, and his heel is in neutral alignment. What is the most appropriate next step in management?

. Repeat percutaneous Achilles tenotomy and serial casting
. Full anterior tibial tendon transfer (TATT) to the lateral cuneiform
. Split anterior tibial tendon transfer (SPLATT)
. Calcaneocuboid fusion (Evans procedure)
. Triple arthrodesis

Correct Answer & Explanation

. Full anterior tibial tendon transfer (TATT) to the lateral cuneiform

Explanation

Dynamic supination during the swing phase in a toddler with a previously corrected clubfoot is a classic presentation of a localized relapse caused by a strong over-pull of the tibialis anterior muscle. Because passive dorsiflexion is well maintained (no fixed equinus), an Achilles tenotomy is not required. The treatment of choice in children (typically aged 2.5 to 5 years) is a full transfer of the anterior tibial tendon (TATT) to the lateral (third) cuneiform. A split transfer (SPLATT) is generally reserved for adult patients with upper motor neuron lesions (e.g., stroke, traumatic brain injury) and is not the standard of care for pediatric clubfoot relapses.

Question 3112

Topic: Pediatric Hip

An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. According to the modified lateral pillar (Herring) classification, which of the following radiographic findings signifies the poorest prognosis for long-term hip congruency?

. Maintenance of >50% but <100% of the lateral pillar height
. Maintenance of <50% of the lateral pillar height
. A subchondral radiolucent line (Crescent sign) involving <50% of the femoral head
. The presence of a positive Gage sign
. Fragmentation of the medial pillar alone

Correct Answer & Explanation

. Maintenance of <50% of the lateral pillar height

Explanation

The Herring (Lateral Pillar) classification evaluates the height of the lateral pillar of the femoral head during the fragmentation stage of Legg-Calvé-Perthes disease. Group A has 100% height maintenance, Group B has >50% maintenance, and Group C has <50% maintenance of the lateral pillar height. Group C carries the worst prognosis for maintaining a spherical, congruent hip joint at skeletal maturity, particularly in patients who present over the age of 8. Group B/C (the modified addition) also represents a borderline poor prognosis.

Question 3113

Topic: Pediatric Upper Extremity & Spine

A 10-year-old premenarcheal girl is incidentally found to have a right thoracic adolescent idiopathic scoliosis (AIS). Upright standing radiographs demonstrate a Cobb angle of 26 degrees. Her Risser stage is 0. Based on standard prognostic criteria (Lonstein and Carlson), what is the approximate risk that this curve will progress to a surgical or bracing threshold (>50 degrees or requiring intervention)?

. 10 - 15%
. 20 - 30%
. 65 - 70%
. Nearly 100%

Correct Answer & Explanation

. 65 - 70%

Explanation

The Lonstein and Carlson progression factor evaluates the risk of curve progression in AIS based on the Cobb angle, Risser stage, and chronological age. A young, premenarcheal patient (Risser 0 or 1) presenting with a curve between 20 and 29 degrees has a high risk of progression, calculated to be approximately 68%. This patient clearly meets the indications for bracing (curve > 25 degrees in an immature patient).

Question 3114

Topic: 4. Pediatrics

A 7-year-old boy with spastic quadriplegic cerebral palsy (GMFCS Level V) presents for routine orthopedic surveillance. His parents report increased difficulty with perineal care. Pelvic radiographs demonstrate a Reimers migration percentage of 55% in the right hip. Clinical exam reveals hip abduction is limited to 15 degrees bilaterally with the hips flexed.

What is the most appropriate management?

. Observation with repeat radiographs in 6 months
. Bilateral adductor longus and gracilis tenotomies
. Varus derotational osteotomy (VDRO) of the proximal femur with a pelvic osteotomy
. Total hip arthroplasty
. Proximal femoral resection arthroplasty

Correct Answer & Explanation

. Varus derotational osteotomy (VDRO) of the proximal femur with a pelvic osteotomy

Explanation

Hip displacement is a common and morbid complication in children with severe cerebral palsy (GMFCS IV and V). A Reimers migration percentage greater than 40-50% indicates significant subluxation that has progressed beyond the capacity of isolated soft-tissue releases (which are typically indicated for migration percentages between 30% and 40%). Reconstructive surgery consisting of a proximal femoral varus derotational osteotomy (VDRO) combined with a pelvic osteotomy (e.g., Dega or San Diego) is the gold standard to achieve a concentric, painless, and stable hip in this setting.

Question 3115

Topic: 4. Pediatrics

A 2-year-old boy, who is above the 95th percentile for weight, presents with bilateral bowing of his legs. Standing AP radiographs show a metaphyseal-diaphyseal angle (MDA) of 18 degrees bilaterally, with early beaking of the medial proximal tibial metaphysis. Which of the following is the most appropriate initial management?

. Reassurance and observation, as this is physiological bowing
. Bilateral knee-ankle-foot orthoses (KAFOs)
. High-dose Vitamin D supplementation
. Bilateral guided growth (tension band plates) of the lateral proximal tibia
. Bilateral proximal tibial valgus osteotomies

Correct Answer & Explanation

. Bilateral knee-ankle-foot orthoses (KAFOs)

Explanation

This presentation is highly characteristic of infantile Blount disease (tibia vara), defined by pathological bowing and a metaphyseal-diaphyseal angle (MDA, or Drennan angle) greater than 16 degrees. While physiological bowing resolves spontaneously and typically has an MDA < 11 degrees, an MDA > 16 degrees demands intervention. The accepted first-line treatment for infantile Blount disease in a child under the age of 3 is bracing with knee-ankle-foot orthoses (KAFOs). Surgery is reserved for those who fail bracing or who present at an older age (typically >4 years) with progressive deformity.

Question 3116

Topic: Pediatric Lower Extremity

A 4-year-old boy treated previously for idiopathic clubfoot with the Ponseti method presents with a relapsed dynamic supination deformity during the swing phase of gait. His passive ankle dorsiflexion is 15 degrees, and the hindfoot is flexible. What is the most appropriate next step in management?

. Tendo-Achilles lengthening alone
. Tibialis anterior tendon transfer to the lateral cuneiform
. Split tibialis posterior tendon transfer
. Talonavicular fusion
. Repeat serial casting followed by percutaneous tenotomy

Correct Answer & Explanation

. Tibialis anterior tendon transfer to the lateral cuneiform

Explanation

For a relapsed dynamic supination deformity in a child who has previously undergone successful Ponseti casting and has flexible deformity and adequate dorsiflexion, a tibialis anterior tendon transfer (TATT) to the lateral cuneiform is the treatment of choice.

Question 3117

Topic: Pediatric Hip

A 6-week-old female infant is placed in a Pavlik harness for a dislocated left hip. After 3 weeks of proper wear, ultrasound demonstrates that the hip remains persistently dislocated. What is the most appropriate next step in management?

. Continue the Pavlik harness for 3 more weeks
. Transition to a rigid abduction orthosis
. Perform an open reduction and spica casting
. Discontinue the harness and perform closed reduction and spica casting
. Obtain an MRI to evaluate for interposed tissue

Correct Answer & Explanation

. Discontinue the harness and perform closed reduction and spica casting

Explanation

Continuation of a Pavlik harness in a persistently dislocated hip beyond 3 to 4 weeks increases the risk of 'Pavlik harness disease' (damage to the posterior wall of the acetabulum) and avascular necrosis. The harness should be discontinued, and the infant should be scheduled for a closed reduction and spica casting.

Question 3118

Topic: 4. Pediatrics

A 14-year-old boy presents with a painful, swollen ankle after a skateboarding fall. Radiographs demonstrate an intra-articular fracture of the anterolateral distal tibial epiphysis. What ligament is responsible for the avulsion of this fracture fragment?

. Anterior talofibular ligament
. Posterior inferior tibiofibular ligament
. Anterior inferior tibiofibular ligament
. Deltoid ligament
. Calcaneofibular ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. It is caused by an avulsion force transmitted through the anterior inferior tibiofibular ligament (AITFL) during external rotation of the foot. It occurs in adolescents because the distal tibial physis closes from central to anteromedial to posteromedial to lateral, leaving the anterolateral physis open and vulnerable.

Question 3119

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 32 undergoes in situ pinning of a stable slipped capital femoral epiphysis (SCFE) with a single cannulated screw. Postoperatively, he has persistent severe pain, limited range of motion, and joint stiffness. Radiographs show joint space narrowing and subchondral radiolucencies. What is the most likely diagnosis?

. Avascular necrosis
. Chondrolysis
. Screw cutout
. Septic arthritis
. Impingement syndrome

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a devastating complication of SCFE characterized by acute loss of articular cartilage, leading to rapid joint space narrowing, stiffness, and severe pain. It is associated with unrecognized screw penetration into the joint. Avascular necrosis typically presents with sclerosis, cysts, and eventual collapse of the femoral head rather than diffuse joint space narrowing early on.

Question 3120

Topic: 4. Pediatrics

A 5-year-old boy with spastic quadriplegic cerebral palsy (GMFCS Level V) is evaluated in the clinic. His bilateral hip migration percentages are calculated to be 45%. He has limited hip abduction to 20 degrees bilaterally. What is the most appropriate management?

. Observation and repeat radiographs in 1 year
. Bilateral adductor tenotomies
. Varus derotational osteotomies (VDRO) and pelvic osteotomies
. Botulinum toxin injections to the adductors
. Selective dorsal rhizotomy

Correct Answer & Explanation

. Varus derotational osteotomies (VDRO) and pelvic osteotomies

Explanation

In non-ambulatory children (GMFCS IV and V) with cerebral palsy, a migration percentage (MP) > 40% usually indicates progressive hip displacement that is unlikely to respond to soft-tissue releases (adductor tenotomies) alone. The standard of care for a hip with an MP > 40% and significant dysplasia is bony reconstructive surgery, which typically involves a varus derotational osteotomy (VDRO) of the proximal femur, often combined with a pelvic osteotomy (e.g., Dega or San Diego).

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