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4. Pediatrics MCQs

Practice Set 257 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 5121

Topic: Pediatric Hip

A 13-year-old obese boy presents with left hip pain and inability to ambulate, even with crutches, following a minor fall. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most significant risk associated with this specific presentation?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Femoroacetabular impingement (FAI)
. Contralateral slip
. Premature osteoarthritis

Correct Answer & Explanation

. Chondrolysis

Explanation

The inability to ambulate with or without crutches defines an unstable SCFE. Unstable SCFE has a significantly higher risk of avascular necrosis (AVN) of the femoral head, with rates historically reported between 20% and 50%.

Question 5122

Topic: Pediatric Upper Extremity & Spine
A 6-year-old girl undergoes closed reduction and percutaneous pinning for a Gartland type III supracondylar humerus fracture. Postoperatively, her hand is warm, pink, and has brisk capillary refill, but the radial pulse remains unpalpable. What is the most appropriate next step in management?
. Immediate exploration of the brachial artery
. Perform a CT angiogram of the upper extremity
. Remove the pins and extend the elbow to 20 degrees
. Observation with close clinical monitoring
. Administer intravenous heparin

Correct Answer & Explanation

. Observation with close clinical monitoring

Explanation

A pink, pulseless hand following reduction and pinning of a supracondylar fracture indicates adequate collateral perfusion. The standard of care is close clinical observation rather than immediate surgical exploration, as the pulse often returns over time.

Question 5123

Topic: Pediatric Hip

An 18-month-old girl presents with untreated developmental dysplasia of the left hip (DDH). Radiographs show a completely dislocated femoral head. Which of the following is the most appropriate initial management?

. Application of a Pavlik harness
. Closed reduction and spica casting
. Open reduction, possible pelvic/femoral osteotomy, and spica casting
. Observation until age 3, then varus derotational osteotomy
. Skeletal traction for 6 weeks followed by bracing

Correct Answer & Explanation

. Application of a Pavlik harness

Explanation

In children older than 18 months with a dislocated hip, closed reduction is rarely successful or stable. Open reduction, often combined with a pelvic or femoral shortening osteotomy, is the treatment of choice to safely reduce the joint.

Question 5124

Topic: Pediatric Hip

A 4-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, the parents report the infant is no longer kicking the right leg. On clinical examination, the infant demonstrates an absence of active knee extension on the right side but has normal ankle movements. What is the most likely cause of this complication?

. Excessive hip flexion in the harness
. Excessive hip abduction in the harness
. Inadequate hip flexion in the harness
. Inadequate hip abduction in the harness
. Avascular necrosis of the femoral head

Correct Answer & Explanation

. Excessive hip flexion in the harness

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness resulting from excessive hip flexion, which compresses the femoral nerve against the rim of the pelvis or inguinal ligament. Excessive hip abduction, in contrast, increases the risk of avascular necrosis (AVN) of the femoral head.

Question 5125

Topic: Pediatric Hip

A 13-year-old obese male presents with an acute inability to bear weight on the left leg. Radiographs reveal a slipped capital femoral epiphysis (SCFE). Which of the following factors at presentation is the most statistically significant predictor for the future development of avascular necrosis (AVN) of the femoral head?

. Severity of the slip angle greater than 50 degrees
. The patient's body mass index (BMI)
. Inability to ambulate with or without crutches (unstable SCFE)
. Duration of preceding chronic groin pain symptoms
. The use of a double-screw construct for fixation

Correct Answer & Explanation

. Severity of the slip angle greater than 50 degrees

Explanation

According to the Loder classification, SCFE is classified into stable (able to bear weight) and unstable (unable to bear weight, even with crutches). Unstable SCFE has a substantially higher risk of developing avascular necrosis (approaching 47% in some series), making weight-bearing status the most important clinical prognostic factor for AVN.

Question 5126

Topic: Pediatric Hip

A 6-year-old boy is diagnosed with Legg-Calve-Perthes disease. When assessing the prognosis using the Herring lateral pillar classification on the AP radiograph of the pelvis during the fragmentation phase, which of the following parameters defines a Type B classification?

. No radiolucency in the lateral pillar
. Greater than 50% of the lateral pillar height is maintained
. Less than 50% of the lateral pillar height is maintained
. Complete collapse of the entire epiphysis with subluxation
. Extrusion of the lateral aspect of the femoral head (Gage sign)

Correct Answer & Explanation

. No radiolucency in the lateral pillar

Explanation

The Herring lateral pillar classification relies on the height of the lateral third of the femoral epiphysis (the lateral pillar) on an AP radiograph during the fragmentation stage. Type A: no involvement. Type B: >50% of lateral pillar height is maintained. Type C: <50% of lateral pillar height is maintained. The classification is highly prognostic for final hip sphericity.

Question 5127

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 32 presents with left-sided slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic right hip?

. Patient's chronological age of 12 years
. Initial left slip angle of 30 degrees
. Underlying endocrine disorder (e.g., hypothyroidism)
. Presence of referred knee pain on the left
. BMI greater than 30

Correct Answer & Explanation

. Patient's chronological age of 12 years

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended for patients with underlying endocrinopathies (like hypothyroidism, panhypopituitarism, or renal osteodystrophy), as they have a significantly higher rate of bilateral involvement (up to 100% in some series) compared to idiopathic cases.

Question 5128

Topic: Pediatric Hip

In the treatment of developmental dysplasia of the hip (DDH) using a Pavlik harness, allowing excessive flexion of the hip beyond 120 degrees places the infant at increased risk for which complication?

. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Obturator nerve palsy
. Inferior dislocation of the hip
. Slipped capital femoral epiphysis

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

In a Pavlik harness, excessive hyperflexion (greater than 120 degrees) risks compressing the femoral nerve, leading to a transient femoral nerve palsy. Excessive abduction is famously associated with avascular necrosis (AVN) of the femoral head.

Question 5129

Topic: Pediatric Hip
In the Herring Lateral Pillar Classification for Legg-Calvรฉ-Perthes disease, a hip demonstrating a lateral pillar that maintains exactly 65% of its original height is classified into which group?
. Group A
. Group B
. Group B/C border
. Group C
. Group D

Correct Answer & Explanation

. Group B

Explanation

The Herring Lateral Pillar Classification relies on the height of the lateral pillar of the femoral head on AP radiograph. Group A has 100% height. Group B maintains >50% of the height. Group C has <50% of the height. Therefore, a lateral pillar at 65% falls squarely into Group B.

Question 5130

Topic: Pediatric Hip

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 2-week follow-up, she presents with an inability to actively extend her knee on the treated side. Which of the following is the most appropriate next step in management?

. Immediate surgical exploration
. Switch to a rigid hip spica cast
. Loosen the anterior straps of the harness
. Loosen the posterior straps of the harness
. Obtain an urgent MRI of the hip

Correct Answer & Explanation

. Immediate surgical exploration

Explanation

The child has developed a femoral nerve palsy, a known complication of extreme hyperflexion in a Pavlik harness. The anterior straps control hip flexion; therefore, loosening them is the appropriate next step to relieve tension on the femoral nerve. Usually, the nerve function recovers completely once flexion is reduced.

Question 5131

Topic: 4. Pediatrics

A 13-year-old obese male presents with right knee pain and an antalgic gait. Examination reveals obligate external rotation of the right hip during passive hip flexion. In this condition, the physeal failure characteristically occurs through which histomorphologic zone of the growth plate?

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

Correct Answer & Explanation

. Reserve zone

Explanation

The patient's presentation is classic for a Slipped Capital Femoral Epiphysis (SCFE). The mechanical failure and slippage of the proximal femoral physis in SCFE typically occurs through the zone of hypertrophy.

Question 5132

Topic: Pediatric Lower Extremity

A neonate is diagnosed with idiopathic clubfoot (talipes equinovarus) and is scheduled to begin serial casting using the Ponseti method. According to this technique, the initial cast must address the first element of the deformity by performing which specific manipulative maneuver?

. Supination of the forefoot and elevation of the first ray to correct cavus
. Pronation of the forefoot to align it with the hindfoot
. Forced dorsiflexion of the ankle to stretch the Achilles tendon
. Abduction of the forefoot with pressure over the cuboid
. Valgus directed pressure on the calcaneus to correct varus

Correct Answer & Explanation

. Supination of the forefoot and elevation of the first ray to correct cavus

Explanation

The Ponseti method addresses clubfoot deformities in the sequence C-A-V-E (Cavus, Adductus, Varus, Equinus). The very first step is to correct the cavus component. This is achieved by supinating the forefoot and elevating the first metatarsal, which aligns the forefoot with the already supinated hindfoot, providing a solid fulcrum for subsequent abduction.

Question 5133

Topic: Pediatric Hip

A 6-week-old female with developmental dysplasia of the hip is treated with a Pavlik harness. After 2 weeks, the mother notes that the infant is no longer actively kicking the affected leg, particularly lacking active knee extension. The most likely cause of this clinical finding is:

. Obturator nerve palsy from excessive abduction
. Sciatic nerve palsy from excessive flexion
. Femoral nerve palsy from hyperflexion
. Tibial nerve palsy from the foot strap
. Avascular necrosis of the femoral head

Correct Answer & Explanation

. Obturator nerve palsy from excessive abduction

Explanation

Femoral nerve palsy is a well-documented complication of the Pavlik harness, typically caused by hyperflexion of the hips compressing the nerve against the inguinal ligament. It presents with decreased active knee extension. Treatment involves adjusting the harness to decrease flexion or temporarily discontinuing it until function returns.

Question 5134

Topic: Pediatric Hip

A 12-year-old boy with a BMI in the 99th percentile presents with a left-sided Slipped Capital Femoral Epiphysis (SCFE) and undergoes in-situ pinning. The parents ask about the risk to his right hip. Which of the following is the most significant risk factor indicating the need for prophylactic pinning of the contralateral, asymptomatic hip?

. Chronological age greater than 14 years
. Hypothyroidism or other endocrinopathy
. Presence of knee pain rather than groin pain
. Left-sided initial presentation
. Male sex

Correct Answer & Explanation

. Chronological age greater than 14 years

Explanation

Prophylactic pinning of the contralateral hip in SCFE is indicated in patients with underlying metabolic or endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) or in very young patients (e.g., modified Oxford bone age < 10 for girls or < 12 for boys) because their risk of developing a contralateral slip approaches 50% to 100%.

Question 5135

Topic: Pediatric Lower Extremity

In the Ponseti method for treating idiopathic clubfoot, which of the following components of the deformity is anatomically corrected last?

. Cavus
. Adductus
. Varus
. Equinus
. Internal tibial torsion

Correct Answer & Explanation

. Cavus

Explanation

In the Ponseti method, the mnemonic CAVE dictates the order of correction: Cavus, Adductus, Varus, and finally Equinus. Equinus is typically corrected last, nearly always requiring a percutaneous Achilles tenotomy.

Question 5136

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 32 presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE) of the left hip. In considering prophylactic pinning of the contralateral, asymptomatic hip, which of the following factors most strongly supports intervention?

. Patient age
. Patient obesity
. Presence of an endocrine disorder
. Male sex
. Severity of the left-sided slip

Correct Answer & Explanation

. Patient age

Explanation

The presence of an endocrine disorder (e.g., hypothyroidism, renal osteodystrophy) significantly increases the risk of a contralateral SCFE, warranting prophylactic pinning. Endocrine etiology is the strongest predictor among these choices.

Question 5137

Topic: Pediatric Hip

A 12-year-old obese male presents with left-sided Slipped Capital Femoral Epiphysis (SCFE). Which of the following is the most accepted indication for prophylactic pinning of the contralateral asymptomatic hip?

. Age greater than 14 years
. Female sex
. Endocrinopathy such as hypothyroidism or renal osteodystrophy
. Mild slip angle (<30 degrees) on the affected side
. Closure of the triradiate cartilage

Correct Answer & Explanation

. Age greater than 14 years

Explanation

Prophylactic pinning of the contralateral hip in SCFE is indicated in patients with endocrinopathies (hypothyroidism, renal osteodystrophy, growth hormone deficiency), previous radiation therapy, and in some centers for very young age (<10 years for boys, <11 for girls) due to the exceedingly high risk of a subsequent contralateral slip.

Question 5138

Topic: Pediatric Hip

A 6-week-old female is being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). During follow-up, she is noted to have decreased active extension of the knee on the treated side. What is the most likely cause?

. Avascular necrosis of the femoral head
. Femoral nerve palsy due to excessive hip flexion
. Obturator nerve palsy due to excessive abduction
. Development of an iatrogenic knee dislocation
. Sciatic nerve palsy due to excessive hip extension

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion of the hip which compresses the nerve against the inguinal ligament. It presents as decreased active extension of the knee. If this occurs, the harness should be adjusted or temporarily discontinued to prevent permanent nerve injury.

Question 5139

Topic: Pediatric Lower Extremity

According to the Ponseti method for treating congenital talipes equinovarus (clubfoot), what is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method corrects the clubfoot deformities in a specific sequence described by the acronym CAVE: Cavus (corrected first by elevating the first ray to align the forefoot with the hindfoot), Adductus, Varus, and finally Equinus (which often requires a percutaneous Achilles tenotomy as the final step).

Question 5140

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls on an outstretched hand and sustains a Gartland type III extension-type supracondylar humerus fracture. Upon examination, he is unable to make an 'OK' sign with his thumb and index finger. Which nerve is most likely injured?
. Ulnar nerve
. Posterior interosseous nerve
. Anterior interosseous nerve
. Musculocutaneous nerve
. Superficial radial nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The anterior interosseous nerve (AIN), a branch of the median nerve, is the most commonly injured nerve in extension-type supracondylar humerus fractures. It innervates the flexor pollicis longus and the flexor digitorum profundus to the index finger, both of which are required to form the 'OK' sign.

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