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4. Pediatrics MCQs

Practice Set 157 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 3121

Topic: Pediatric Hip

A 7-year-old boy presents with a painless limp of 3 months duration. Radiographs confirm the diagnosis of Legg-Calve-Perthes disease. Which of the following is considered a 'head at risk' sign indicating a poorer prognosis and potential need for surgical intervention?

. Medial subluxation of the femoral head
. Gage sign
. Presence of a subchondral fracture (Crescent sign)
. Decreased alpha angle
. Acetabular dysplasia

Correct Answer & Explanation

. Gage sign

Explanation

Catterall described several 'head at risk' signs in Legg-Calve-Perthes disease that indicate a poor prognosis and a higher likelihood of femoral head deformity. These include Gage sign (a V-shaped radiolucency in the lateral portion of the epiphysis/metaphysis), lateral subluxation of the femoral head, calcification lateral to the epiphysis, horizontal growth plate, and metaphyseal cysts.

Question 3122

Topic: Pediatric Hip

A 13-year-old boy presents with severe right hip and thigh pain after a minor slip. He is unable to bear weight on the right leg. He reports a 2-month history of intermittent right knee pain prior to this event. On examination, attempted hip flexion results in obligatory external rotation. Radiographs confirm a displaced slipped capital femoral epiphysis (SCFE).

What is the most appropriate management to minimize the risk of avascular necrosis (AVN) in this patient?

. Urgent percutaneous in situ fixation within 24 hours
. Delayed percutaneous in situ fixation after 72 hours to allow swelling to subside
. Closed reduction and spica casting
. Skeletal traction for 1 week followed by in situ pinning
. Subtrochanteric derotational osteotomy

Correct Answer & Explanation

. Urgent percutaneous in situ fixation within 24 hours

Explanation

This patient has an unstable Slipped Capital Femoral Epiphysis (SCFE), defined by the Loder classification as the inability to bear weight even with crutches. Unstable SCFE carries a significantly higher risk of avascular necrosis (AVN) compared to stable SCFE (up to 50% vs. nearly 0%). Current evidence strongly supports urgent surgical intervention (within 24 hours of symptom onset) via in situ percutaneous pinning or an open procedure (like a modified Dunn) depending on the surgeon's expertise. Urgent decompression/pinning decreases the intracapsular pressure and stabilizes the physis, significantly lowering the AVN rate compared to delayed treatment. Traction and spica casting are historically associated with poor outcomes and are no longer standard of care.

Question 3123

Topic: Pediatric Upper Extremity & Spine

A 5-year-old boy sustains a completely displaced supracondylar humerus fracture (Gartland Type III). Upon presentation, his hand is pink, but the radial pulse is absent. He undergoes urgent closed reduction and percutaneous pinning.

In the recovery room, the fracture is well-reduced, the hand remains pink and warm with a capillary refill of less than 2 seconds, and oxygen saturation on the index finger is 99%; however, the radial pulse remains nonpalpable. What is the most appropriate next step in management?

. Immediate operative exploration of the brachial artery
. Removal of the pins and transition to an open reduction
. CT angiography of the upper extremity
. Observation and hospital admission for neurovascular monitoring
. Administration of intra-arterial vasodilators

Correct Answer & Explanation

. Observation and hospital admission for neurovascular monitoring

Explanation

The 'pulseless, pink, perfused' hand after adequate closed reduction and percutaneous pinning of a supracondylar humerus fracture is a well-recognized clinical entity. Because the hand is well perfused (capillary refill <2 seconds, good warmth, and normal pulse oximetry), collateral circulation is adequate. The standard of care is admission for 24 to 48 hours for close neurovascular monitoring. Operative exploration of the brachial artery is only indicated if the hand becomes dysvascular (pulseless, pale, cold) after reduction, or if there is impending compartment syndrome.

Question 3124

Topic: 4. Pediatrics

An 18-month-old girl presents with a painless limp. Her parents note that her left leg appears shorter than the right. On examination, Galeazzi sign is positive on the left, and hip abduction is restricted. Radiographs demonstrate a completely dislocated left hip with a broken Shenton's line and an acetabular index of 42 degrees.

Which of the following is the most appropriate definitive management?

. Application of a Pavlik harness
. Closed reduction and spica casting
. Botulinum toxin injection to the adductors and abduction bracing
. Open reduction with an expected need for a concomitant pelvic osteotomy
. Observation until age 4 followed by a salvage osteotomy

Correct Answer & Explanation

. Open reduction with an expected need for a concomitant pelvic osteotomy

Explanation

In a child of walking age (typically older than 18 months) presenting with a newly diagnosed, completely dislocated hip due to Developmental Dysplasia of the Hip (DDH), closed reduction is rarely successful or adequate. Due to secondary adaptive changes, including acetabular dysplasia (evidenced by an acetabular index of 42 degrees) and contractures, open reduction is required. Furthermore, a concomitant pelvic osteotomy (e.g., Salter or Pemberton) is almost always necessary to provide adequate anterolateral coverage for the femoral head and ensure stability. A femoral shortening osteotomy may also be needed to reduce pressure on the proximal femoral physis and decrease the risk of avascular necrosis.

Question 3125

Topic: 4. Pediatrics

A 4-year-old boy with a history of idiopathic congenital talipes equinovarus initially successfully treated with the Ponseti method presents with recurrent in-toeing and lateral foot wear. On examination, he demonstrates a dynamic supination of the foot during the swing phase of gait. His passive range of motion is full, the foot is completely correctable passively, and there is no fixed equinus. What is the most appropriate surgical intervention?

. Extensive posteromedial release
. Transfer of the entire anterior tibial tendon (TATT) to the lateral cuneiform
. Split anterior tibial tendon transfer (SPLATT) to the cuboid
. Lateral column lengthening
. Percutaneous Achilles tendon lengthening

Correct Answer & Explanation

. Transfer of the entire anterior tibial tendon (TATT) to the lateral cuneiform

Explanation

The patient presents with dynamic supination and recurrent in-toeing, a common manifestation of a relapsed clubfoot treated with the Ponseti method. Because the deformity is dynamic and passively correctable, bony procedures or extensive soft tissue releases are not indicated. The treatment of choice for a dynamic supination deformity in a relapsed Ponseti clubfoot is the transfer of the entire Tibialis Anterior Tendon (TATT) to the third (lateral) cuneiform. A split anterior tibial tendon transfer (SPLATT) is less predictable in this specific condition and is more commonly used in cerebral palsy or adult acquired deformities.

Question 3126

Topic: Pediatric Hip

An 8-year-old boy is evaluated for an 8-month history of right hip pain and a painless limp.

AP pelvis radiographs demonstrate fragmentation of the right capital femoral epiphysis consistent with Legg-Calvé-Perthes disease. According to the Herring Lateral Pillar Classification, which of the following defines a Lateral Pillar Group C hip, which carries the poorest prognosis?

. No involvement of the lateral pillar with normal height
. Maintenance of >50% of the normal lateral pillar height
. Maintenance of <50% of the normal lateral pillar height
. A subchondral crescent sign extending >50% of the femoral head width
. Calcification lateral to the epiphyseal margin

Correct Answer & Explanation

. Maintenance of <50% of the normal lateral pillar height

Explanation

The Herring Lateral Pillar Classification is the most widely used prognostic radiographic classification for Legg-Calvé-Perthes disease, evaluated during the fragmentation stage on the AP radiograph. Group A involves no radiolucency or loss of height in the lateral third of the epiphysis (lateral pillar). Group B demonstrates a lucency but maintains >50% of the lateral pillar height. Group C involves a loss of >50% of the lateral pillar height (i.e., maintenance of <50%). Group C hips have the poorest prognosis, frequently leading to a flat, aspherical head and early-onset osteoarthritis.

Question 3127

Topic: 4. Pediatrics

A 2-and-a-half-year-old girl is evaluated for bilateral bowlegs. Standing AP radiographs of the lower extremities are obtained.

Which of the following radiographic parameters is most reliable in differentiating infantile Blount disease from physiologic genu varum?

. Metaphyseal-diaphyseal angle (MDA) greater than 16 degrees
. Tibiofemoral angle of 15 degrees varus
. Medial physeal slope greater than 10 degrees
. Mechanical axis deviation passing through the medial compartment
. Femoral bowing greater than tibial bowing

Correct Answer & Explanation

. Metaphyseal-diaphyseal angle (MDA) greater than 16 degrees

Explanation

The metaphyseal-diaphyseal angle (MDA) of Drennan is the most reliable radiographic parameter used to differentiate infantile Blount disease from physiologic genu varum. An MDA greater than 16 degrees is highly predictive of progressive infantile Blount disease, whereas an MDA less than 11 degrees suggests physiologic bowing that will likely resolve spontaneously. Values between 11 and 16 degrees warrant close observation and serial radiographs. Tibiofemoral angle and mechanical axis deviation do not reliably differentiate the two entities in this age group, as both are present in physiologic bowing.

Question 3128

Topic: Pediatric Upper Extremity & Spine

A 12-year-old girl presents for evaluation of a spinal deformity. Standing posteroanterior radiographs demonstrate a right thoracic adolescent idiopathic scoliosis (AIS) with a Cobb angle of 22 degrees.

Which of the following parameters indicates that the patient is currently in the period of maximum risk for rapid curve progression?

. Risser stage 4
. Menarche occurring 18 months ago
. Closure of the triradiate cartilage
. Peak height velocity
. Sanders skeletal stage 7

Correct Answer & Explanation

. Peak height velocity

Explanation

The risk of progression in adolescent idiopathic scoliosis (AIS) is most strongly correlated with the patient's remaining growth potential. The period of maximum growth—and thus maximum curve progression risk—is during peak height velocity (PHV). PHV typically occurs before menarche, before the closure of the triradiate cartilage, and at Risser stage 0 (typically Sanders stage 3). Risser stage 4, post-menarche status, and Sanders stage 7 all indicate advanced skeletal maturity and a significantly lower risk of curve progression.

Question 3129

Topic: Pediatric Hip

A 12-year-old obese boy presents with 3 weeks of vague knee pain and a limp. Examination reveals obligate external rotation of the hip during flexion. He is diagnosed with a stable slipped capital femoral epiphysis (SCFE).

What is the most appropriate position to place the hip during in situ single-screw fixation to minimize the risk of osteonecrosis?

. Maximum internal rotation to reduce the slip
. Maximum abduction and flexion
. Resting position without attempting reduction
. Anatomical neutral position regardless of the slip
. Maximum external rotation to distract the joint

Correct Answer & Explanation

. Resting position without attempting reduction

Explanation

For a stable slipped capital femoral epiphysis (SCFE), the standard of care is in situ fixation with a single cannulated screw. Attempting to forcefully reduce a stable SCFE significantly increases the risk of osteonecrosis (avascular necrosis) of the femoral head due to disruption of the delicate epiphyseal blood supply. Therefore, the hip should be pinned in its resting position without deliberate attempts at reduction.

Question 3130

Topic: Pediatric Upper Extremity & Spine

A 5-year-old girl falls from the monkey bars and sustains a Gartland type III extension-type supracondylar humerus fracture.

On presentation, she has a pulseless, pink hand. After prompt closed reduction and percutaneous pinning, her hand remains warm and pink with a capillary refill of 2 seconds, but the radial pulse is still non-palpable. What is the most appropriate next step in management?

. Immediate open exploration of the brachial artery
. Observation with admission for close neurovascular monitoring
. Urgent CT angiography of the upper extremity
. Removal of the pins and open reduction of the fracture
. Prophylactic volar forearm fasciotomy

Correct Answer & Explanation

. Observation with admission for close neurovascular monitoring

Explanation

A pulseless, pink hand is a well-recognized clinical scenario following a displaced supracondylar humerus fracture. If the hand remains well-perfused (pink, warm, brisk capillary refill) after anatomical reduction and stabilization, collateral circulation is adequate. The standard of care is to admit the patient for close observation and serial neurovascular checks. Open vascular exploration is indicated if the hand is pulseless AND poorly perfused (pale/white) after reduction.

Question 3131

Topic: 4. Pediatrics
A 7-year-old boy presents with a painless limp of 3 months' duration. Radiographs demonstrate sclerosis and fragmentation of the capital femoral epiphysis, leading to a diagnosis of Legg-Calvé-Perthes disease. Which of the following radiographic findings is a "head-at-risk" sign described by Catterall, indicating a poorer prognosis?
. Medial subluxation of the femoral head
. Central epiphyseal fragmentation
. Gage sign
. Intact lateral pillar
. Widening of the acetabular teardrop

Correct Answer & Explanation

. Gage sign

Explanation

Catterall identified specific "head-at-risk" clinical and radiographic signs that portend a worse prognosis and a higher likelihood of femoral head deformation in Perthes disease. The radiographic signs include: 1) Gage sign (a V-shaped radiolucency in the lateral portion of the epiphysis and adjacent metaphysis), 2) calcification lateral to the epiphysis, 3) lateral (not medial) subluxation of the femoral head, 4) horizontal physis, and 5) metaphyseal cysts.

Question 3132

Topic: Pediatric Hip

A 30-month-old girl is brought in by her parents who noticed she walks with a limp. She has not received any prior orthopedic care. Pelvic radiographs reveal a completely dislocated left hip with acetabular dysplasia and a false acetabulum.

What is the most appropriate definitive management?

. Application of a Pavlik harness
. Closed reduction and spica casting
. Open reduction, femoral shortening osteotomy, and pelvic osteotomy
. Open reduction and spica casting without osteotomies
. Observation until skeletal maturity

Correct Answer & Explanation

. Open reduction, femoral shortening osteotomy, and pelvic osteotomy

Explanation

In a child older than 2 years (24 months) presenting with untreated developmental dysplasia of the hip (DDH) and a high dislocation, closed reduction is rarely successful and carries an unacceptably high risk of osteonecrosis. The gold standard is open reduction. Because the soft tissues are contracted and the acetabulum is dysplastic, a femoral shortening osteotomy (to reduce tension and AVN risk) and a pelvic osteotomy (to address acetabular dysplasia) are typically required simultaneously.

Question 3133

Topic: Pediatric Upper Extremity & Spine
A 13-year-old premenarchal girl (Risser 0) presents for evaluation of a spinal deformity. Neurological examination is completely normal. Standing PA spine radiograph reveals a right thoracic curve measuring 35 degrees. What is the most appropriate next step in management?
. Observation with repeat radiographs in 6 months
. Schroth physical therapy method alone
. Prescription of a rigid thoracolumbosacral orthosis (TLSO)
. Posterior spinal fusion with pedicle screws
. Magnetically controlled growing rods (MCGR)

Correct Answer & Explanation

. Prescription of a rigid thoracolumbosacral orthosis (TLSO)

Explanation

This patient has Adolescent Idiopathic Scoliosis (AIS). She has significant remaining growth potential (premenarchal, Risser 0) and a curve magnitude between 25 and 45 degrees. According to the Bracing in Adolescent Idiopathic Scoliosis Trial (BRAIST) criteria, the standard of care for a skeletally immature patient with a curve of this magnitude is a rigid brace (e.g., TLSO) worn for at least 18 hours a day to prevent curve progression to surgical magnitude (>50 degrees).

Question 3134

Topic: Pediatric Hip

A 12-year-old boy presents to the emergency department unable to bear weight on his left leg for the past 2 days after jumping off a swing. He refuses to walk even with crutches. Figure 4 shows the AP pelvis radiograph.

He is diagnosed with a slipped capital femoral epiphysis (SCFE) and undergoes urgent single-screw in situ fixation. Which of the following is the most likely complication associated with this specific type of presentation compared to a patient who is able to bear weight?

. Chondrolysis
. Avascular necrosis
. Progressive slippage
. Femoroacetabular impingement
. Contralateral slip

Correct Answer & Explanation

. Avascular necrosis

Explanation

The patient has an unstable slipped capital femoral epiphysis (SCFE), defined by the Loder classification as the inability to bear weight with or without crutches. The most significant and common severe complication of an unstable SCFE is avascular necrosis (AVN) of the femoral head, with rates historically reported up to nearly 50%, compared to near 0% in stable SCFE. Urgent, gentle reduction or in situ pinning is required, though the risk of AVN remains high.

Question 3135

Topic: Pediatric Lower Extremity

A 2-week-old newborn with idiopathic clubfoot is being treated with serial casting via the Ponseti method. During the manipulative phase, to correct the deformity, the forefoot must be abducted. To prevent a common technical error and properly correct the deformity, counter-pressure must be applied directly to which of the following structures?

. Calcaneocuboid joint
. Lateral aspect of the talar head
. Medial malleolus
. Navicular
. Base of the fifth metatarsal

Correct Answer & Explanation

. Lateral aspect of the talar head

Explanation

The Ponseti method is the gold standard for correcting idiopathic clubfoot. The correction sequence is CAVE (Cavus, Adductus, Varus, Equinus). When correcting the adductus and varus by abducting the forefoot, the fulcrum for correction is the lateral aspect of the talar head. A common error is applying counter-pressure to the calcaneocuboid joint or the base of the fifth metatarsal, which fails to correct the talonavicular subluxation and can cause a spurious correction or midfoot breach.

Question 3136

Topic: Pediatric Hip

An 18-month-old girl presents with a waddling gait and a painless limp. Figure 10 shows her AP pelvis radiograph demonstrating a dislocated left hip.

She is scheduled to undergo an open reduction of the hip. Which of the following structures represents an EXTRA-articular obstacle to reduction that typically requires division or lengthening?

. Transverse acetabular ligament
. Iliopsoas tendon
. Ligamentum teres
. Pulvinar
. Inverted limbus

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

In Developmental Dysplasia of the Hip (DDH), surgical reduction must overcome both extra-articular and intra-articular obstacles. The iliopsoas tendon is a primary extra-articular obstacle, as it tents over the capsule and constricts it (creating an hourglass shape), preventing the femoral head from entering the true acetabulum. Intra-articular obstacles include the pulvinar (fibrofatty tissue), ligamentum teres, inverted limbus, and the transverse acetabular ligament, all of which may need to be excised, incised, or divided to seat the head concentrically.

Question 3137

Topic: Pediatric Hip
An 8-year-old boy presents with a 4-month history of a painless right-sided limp. Radiographs demonstrate fragmentation of the capital femoral epiphysis consistent with Legg-Calvé-Perthes disease. According to the Herring lateral pillar classification, greater than 50% loss of lateral pillar height is noted (Type C). Which of the following factors in this patient is most strongly associated with a poor prognosis and often dictates the need for surgical containment?
. Male gender
. Unilateral involvement
. Age at onset of 8 years or older
. Presence of a subchondral crescent sign
. Painless presentation

Correct Answer & Explanation

. Age at onset of 8 years or older

Explanation

In Legg-Calvé-Perthes disease, the two most critical prognostic factors are the age at onset and the degree of lateral pillar involvement (Herring classification). Children who develop the disease at 8 years of age or older have less time for the femoral head to remodel before skeletal maturity and generally have worse outcomes, particularly if they have lateral pillar B or C involvement. Surgical containment (e.g., femoral or pelvic osteotomy) is often indicated in this age group to maintain sphericity.

Question 3138

Topic: 4. Pediatrics
A 2.5-year-old girl is evaluated for worsening bilateral genu varum. Standing radiographs reveal a metaphyseal-diaphyseal angle (MDA) of 20 degrees bilaterally with early beaking of the medial proximal tibial metaphysis. She is diagnosed with infantile Blount disease (Langenskiöld stage II). What is the most appropriate initial management?
. Reassurance and annual observation
. Full-time knee-ankle-foot orthosis (KAFO)
. Proximal tibial valgus osteotomy
. Hemiepiphysiodesis of the lateral proximal tibia
. Guided growth of the medial proximal tibia

Correct Answer & Explanation

. Full-time knee-ankle-foot orthosis (KAFO)

Explanation

This child has infantile Blount disease. A metaphyseal-diaphyseal angle (MDA) of >16 degrees is highly predictive of progressive infantile Blount disease rather than physiologic bowing. For children under the age of 3 with Langenskiöld stage I or II, nonoperative treatment with a knee-ankle-foot orthosis (KAFO) is the gold standard initial treatment. Surgery is indicated if bracing fails, if the child is over 4 years old at presentation, or for advanced Langenskiöld stages (III and above).

Question 3139

Topic: 4. Pediatrics
A 13-year-old girl presents with ankle pain after a twisting injury while skateboarding. Radiographs and a subsequent CT scan reveal a Salter-Harris III fracture of the anterolateral distal tibial epiphysis with 3 mm of displacement. Which of the following ligaments is responsible for the avulsion of this fracture fragment?
. Anterior inferior tibiofibular ligament
. Posterior inferior tibiofibular ligament
. Anterior talofibular ligament
. Calcaneofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament

Explanation

The patient has a juvenile Tillaux fracture, which is a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. This injury occurs during the transitional period of physeal closure (which closes centrally, then medially, then laterally). The mechanism involves an external rotation force applied to the foot, causing the anterior inferior tibiofibular ligament (AITFL) to avulse the anterolateral aspect of the epiphysis, which is the last portion to fuse.

Question 3140

Topic: Pediatric Hip

A 12-year-old obese boy presents with 3 weeks of right knee pain and a limp. Examination demonstrates obligate external rotation with hip flexion. An AP pelvis radiograph is shown in Figure 1.

He is diagnosed with a stable slipped capital femoral epiphysis (SCFE) and is scheduled for in situ pinning. What is the most reliable technical maneuver to prevent the devastating complication of chondrolysis during this procedure?

. Pin placement in the anterosuperior quadrant of the epiphysis
. Utilization of a smooth, unthreaded pin
. Using the approach-withdrawal fluoroscopic technique
. Performing a routine open arthrotomy
. Advancing the screw to within 1 mm of the subchondral bone

Correct Answer & Explanation

. Using the approach-withdrawal fluoroscopic technique

Explanation

The most common cause of chondrolysis following SCFE fixation is unrecognized intra-articular hardware penetration. The approach-withdrawal technique utilizes continuous live fluoroscopy while rotating the hip to dynamically verify that the screw tip remains entirely within the bone and has not violated the joint space, thus preventing chondrolysis. Pin placement should ideally be in the center-center position, not anterosuperior.

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