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4. Pediatrics MCQs

Practice Set 96 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 1901

Topic: Pediatric Upper Extremity & Spine
A 6-year-old child sustains a completely displaced Gartland Type III extension-type supracondylar humerus fracture. The anterior interosseous nerve (AIN) is anatomically at the highest risk for injury in this specific fracture pattern. Which of the following physical exam findings definitively confirms an isolated AIN palsy?
. Inability to forcefully abduct the fingers
. Numbness over the dorsal aspect of the first web space
. Inability to flex the interphalangeal joint of the thumb and distal interphalangeal joint of the index finger
. Inability to actively extend the wrist and metacarpophalangeal joints
. Loss of two-point discrimination on the volar aspect of the little finger

Correct Answer & Explanation

. Inability to flex the interphalangeal joint of the thumb and distal interphalangeal joint of the index finger

Explanation

The anterior interosseous nerve (AIN) is a purely motor branch of the median nerve that is frequently stretched or tethered over the proximal fracture fragment in extension-type supracondylar humerus fractures. It innervates the flexor pollicis longus (FPL), the flexor digitorum profundus (FDP) to the index (and sometimes middle) finger, and the pronator quadratus. An isolated AIN palsy manifests as the inability to form an 'OK' sign, presenting as a 'pinch' posture with the thumb IP and index DIP joints extended.

Question 1902

Topic: Pediatric Hip

A 12-year-old obese boy presents with 3 weeks of vague knee pain and a new inability to bear weight on the right leg. On physical examination, the affected leg is resting in external rotation. What is the most significant clinical risk factor for the development of avascular necrosis (AVN) in this patient's condition?

. Duration of symptoms prior to presentation
. Degree of initial slip angle
. Unstable nature of the slip
. Patient's body mass index
. Concomitant endocrine disorder

Correct Answer & Explanation

. Unstable nature of the slip

Explanation

The patient has a Slipped Capital Femoral Epiphysis (SCFE). The inability to bear weight, even with crutches, defines an 'unstable' SCFE according to Loder's classification. Unstable SCFE carries a significantly higher risk of avascular necrosis (nearly 47%) compared to stable SCFE (less than 10%).

Question 1903

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the two-week follow-up, the mother notes the infant has stopped kicking with the affected leg. On examination, active knee extension is absent, though passive motion is full. Which of the following complications has most likely occurred?

. Avascular necrosis of the femoral head
. Obturator nerve palsy
. Femoral nerve palsy
. Sciatic nerve palsy
. Superior gluteal nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness if the hip is hyperflexed (usually > 120 degrees). It presents as decreased active knee extension and quadriceps firing. It is usually reversible upon decreasing the amount of hip flexion.

Question 1904

Topic: Pediatric Hip

A 13-year-old obese male presents with left thigh pain and a limp. He walks with an externally rotated leg. Radiographs reveal a severe slipped capital femoral epiphysis (SCFE) with a slip angle of 60 degrees. What is the most significant risk associated with performing an acute anatomical reduction prior to pinning?

. Chondrolysis
. Avascular necrosis of the femoral head
. Femoroacetabular impingement
. Subtrochanteric fracture
. Leg length discrepancy

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Acute anatomical reduction of a SCFE is highly associated with stretching or kinking of the retinacular vessels, leading to avascular necrosis (AVN) of the femoral head. Therefore, in-situ pinning is the gold standard for stable slips, though unstable slips may require gentle reduction or open procedures (e.g., modified Dunn).

Question 1905

Topic: Pediatric Lower Extremity

When managing a congenital talipes equinovarus (clubfoot) using the Ponseti method, the first step in the casting sequence aims to correct which deformity?

. Equinus
. Cavus
. Varus
. Adductus
. Forefoot pronation

Correct Answer & Explanation

. Cavus

Explanation

The Ponseti method corrects the deformities of clubfoot in a specific sequence (CAVE). The first step is the correction of Cavus by elevating the first ray to align the forefoot with the hindfoot, supinating the forefoot.

Question 1906

Topic: Pediatric Hip



An 8-year-old child presents with a limp and poorly localized knee pain. Radiographs confirm a unilateral slipped capital femoral epiphysis (SCFE). Given the patient's age, an endocrine workup is indicated. Which of the following is the most common underlying endocrine abnormality associated with SCFE in this patient population?

. Hyperparathyroidism
. Hypothyroidism
. Growth hormone deficiency
. Panhypopituitarism
. Testosterone deficiency

Correct Answer & Explanation

. Hypothyroidism

Explanation

While idiopathic SCFE typically occurs during the adolescent growth spurt (ages 10-14 for girls, 12-16 for boys), patients who present 'out of age range' (< 10 years or > 16 years) or whose weight is less than the 50th percentile have a high association with endocrine disorders. Hypothyroidism is the most commonly associated endocrine disorder in patients with SCFE. Other causes include panhypopituitarism, growth hormone supplementation, and renal osteodystrophy.

Question 1907

Topic: 4. Pediatrics

An infant is diagnosed with severe, rigid idiopathic congenital talipes equinovarus (clubfoot). Treatment using the Ponseti method is initiated. According to the specific sequence of the Ponseti method, what is the required primary manipulation in the first casting to correct the multi-planar deformity?

. Elevate the first ray to supinate the forefoot
. Pronate the forefoot to stretch the plantar fascia
. Abduct the midfoot with counter-pressure on the calcaneocuboid joint
. Dorsiflex the ankle to stretch the Achilles tendon
. Evert the calcaneus to correct hindfoot varus

Correct Answer & Explanation

. Elevate the first ray to supinate the forefoot

Explanation

The mnemonic for Ponseti casting is CAVE (Cavus, Adductus, Varus, Equinus). The very first step must be correction of the cavus deformity. The cavus in a clubfoot is caused by a pronated forefoot relative to the hindfoot. To correct this, the first ray is elevated, which supinates the forefoot so that it is in the same plane as the hindfoot. Once the cavus is corrected, the entire foot can be abducted (with counter-pressure over the lateral aspect of the talar head, NOT the calcaneocuboid joint) to simultaneously correct adductus and varus. Equinus is addressed last, often requiring a percutaneous Achilles tenotomy.

Question 1908

Topic: Pediatric Upper Extremity & Spine
A patient sustained a C6 burst fracture in a diving accident. On initial neurological examination in the ICU, he demonstrates active wrist extension against gravity (Grade 3/5) but no active triceps or hand intrinsic function. He has no voluntary anal contraction, but he has preserved sensation to pinprick in the perianal area (S4-S5). Additionally, he has trace voluntary movement of his right great toe (Grade 1/5). According to the ASIA Impairment Scale (AIS), how should this patient be classified?
. AIS A
. AIS B
. AIS C
. AIS D
. AIS E

Correct Answer & Explanation

. AIS C

Explanation

The ASIA Impairment Scale classifies spinal cord injuries. The presence of ANY sacral sparing (perianal sensation or voluntary anal contraction) means the injury is incomplete (eliminating AIS A). Because there is motor function preserved more than 3 levels below the motor level (trace toe movement), the patient is motor incomplete. To differentiate between AIS C and AIS D, one evaluates the muscle grades below the neurological level: in AIS C, less than half of key muscle functions below the neurological level have a muscle grade of โ‰ฅ 3. In AIS D, at least half have a grade of โ‰ฅ 3. Since this patient only has trace (Grade 1) distal motor function, he is AIS C.

Question 1909

Topic: Pediatric Hip

Prophylactic pinning of the contralateral hip in a patient with a Slipped Capital Femoral Epiphysis (SCFE) is most strongly indicated in which of the following scenarios?

. 12-year-old male with idiopathic SCFE
. 14-year-old female with obesity
. 10-year-old male with hypothyroidism
. 15-year-old male with acute-on-chronic SCFE
. 13-year-old female with a positive Klein's line intersection

Correct Answer & Explanation

. 10-year-old male with hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is generally indicated in patients at high risk for bilateral disease. Risk factors for bilateral SCFE include young age at presentation (< 10 years for girls, < 11 years for boys), endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy), and previous radiation therapy. Thus, the 10-year-old male with hypothyroidism represents the highest risk among the choices.

Question 1910

Topic: Pediatric Hip

A 6-month-old female is evaluated for developmental dysplasia of the hip (DDH). Radiographs are obtained.

Which radiographic line is drawn vertically downwards from the lateral edge of the acetabulum to assess hip subluxation?

. Hilgenreiner's line
. Perkin's line
. Shenton's line
. Klein's line
. Southwick's angle

Correct Answer & Explanation

. Perkin's line

Explanation

Perkin's line is a vertical line drawn downward from the lateral margin of the acetabulum, perpendicular to Hilgenreiner's line (which is drawn horizontally through the triradiate cartilages). In a normal hip, the ossific nucleus of the femoral head should sit in the lower medial quadrant created by the intersection of these two lines.

Question 1911

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department with severe acute groin and thigh pain after a minor slip. He is unable to bear weight on the affected limb, even with the assistance of crutches. Radiographs confirm a severe Slipped Capital Femoral Epiphysis (SCFE). Which of the following complications is most specifically associated with this patient's clinical presentation compared to a patient who can bear weight?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Premature physeal closure
. Femoroacetabular impingement (FAI)
. Leg length discrepancy

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The inability to bear weight with or without crutches defines an 'unstable' SCFE according to the Loder classification. Unstable SCFE has a significantly higher rate of avascular necrosis (AVN) of the femoral head, with rates historically reported between 20% and 50%. Stable SCFE (where the patient can bear weight) has a very low risk of AVN (<10%).

Question 1912

Topic: Pediatric Lower Extremity

A 2-week-old infant with idiopathic clubfoot (talipes equinovarus) is brought to the clinic to begin the Ponseti method of serial casting. According to the Ponseti principles, what is the proper sequence of correcting the components of the clubfoot deformity?

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

Correct Answer & Explanation

. Cavus, then Adductus, then Varus, then Equinus

Explanation

The Ponseti method strictly follows a specific sequence of correction, remembered by the acronym CAVE: Cavus, Adductus, Varus, Equinus. The first step is to correct the cavus by elevating the first ray, which aligns the forefoot with the hindfoot. Next, the forefoot is abducted (supinated) around the head of the talus, which simultaneously corrects the adductus and the hindfoot varus. Finally, once the foot is fully abducted, the equinus is addressed, typically requiring a percutaneous Achilles tenotomy.

Question 1913

Topic: Pediatric Hip

A 6-week-old female infant is undergoing treatment for Developmental Dysplasia of the Hip (DDH) with a Pavlik harness. During a routine follow-up, her mother notes that the baby has stopped kicking her right leg. On examination, there is an absence of active knee extension on the right side, but ankle and toe movements are intact. What is the most appropriate management step to address this complication?

. Adjust the posterior straps to decrease hip abduction
. Adjust the anterior straps to decrease hip flexion
. Immediately abandon the Pavlik harness and transition to a hip spica cast
. Obtain an urgent MRI of the lumbar spine
. Reassure the mother and continue the current harness settings

Correct Answer & Explanation

. Adjust the anterior straps to decrease hip flexion

Explanation

The infant is presenting with a femoral nerve palsy, a known complication of Pavlik harness treatment. It is caused by excessive flexion of the hip, which compresses the femoral nerve against the inguinal ligament or pelvic brim. The immediate management is to adjust the anterior straps to slightly decrease the amount of hip flexion. The condition is usually transient and resolves once the hyperflexion is corrected. Adjusting the posterior straps addresses abduction (excessive abduction risks AVN, not femoral nerve palsy).

Question 1914

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department unable to bear weight on his left leg after a minor twisting injury. Radiographs show a slipped capital femoral epiphysis (SCFE).

According to the Loder classification, what is the most significant risk associated with this patient's injury type?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Coxa magna
. Femoroacetabular impingement (FAI)
. Premature physeal closure

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The Loder classification divides SCFE into stable (patient can bear weight with or without crutches) and unstable (patient is unable to bear weight even with crutches). Unstable SCFE has a high rate of avascular necrosis (AVN), ranging from 20% to 50%, whereas stable SCFE has an AVN rate of nearly zero.

Question 1915

Topic: 4. Pediatrics

A 6-year-old child sustains a displaced extension-type supracondylar humerus fracture. On presentation, the radial pulse is absent, but the hand is warm and well-perfused (pink). Closed reduction and percutaneous pinning are performed. Post-operatively, the hand remains warm and pink, but the radial pulse is still absent on palpation and Doppler. What is the most appropriate next step in management?

. Immediate exploration of the brachial artery
. CT angiography of the upper extremity
. Arteriography in the operating room
. Close clinical observation
. Administration of intravenous heparin

Correct Answer & Explanation

. Close clinical observation

Explanation

The management of a 'pulseless, pink' hand after reduction and pinning of a supracondylar humerus fracture is close clinical observation. As long as the hand remains well-perfused (warm, pink, capillary refill < 2 seconds), there is adequate collateral circulation, and surgical exploration is not indicated. Most pulses will return within days to weeks. If the hand were pulseless and pale (ischemic), urgent exploration of the brachial artery would be required.

Question 1916

Topic: Pediatric Hip

A 12-year-old obese male presents with left groin pain and an altered gait.

Based on the presumed diagnosis of slipped capital femoral epiphysis (SCFE) shown in the representative radiograph, which of the following is the primary blood supply to the femoral head that is at highest risk for iatrogenic injury during percutaneous in situ pinning if the pin is placed in the posterosuperior quadrant?

. Anterior ascending branch of the lateral circumflex femoral artery
. Posterosuperior retinacular vessels from the medial circumflex femoral artery
. Foveal artery from the obturator artery
. Inferior gluteal artery branches
. Medial epiphyseal artery

Correct Answer & Explanation

. Posterosuperior retinacular vessels from the medial circumflex femoral artery

Explanation

The primary blood supply to the capital femoral epiphysis in children over the age of 3 is the posterosuperior retinacular vessels (lateral epiphyseal artery), which are terminal branches of the medial circumflex femoral artery (MCFA). During in situ pinning for SCFE, placement of the pin in the posterosuperior quadrant of the femoral neck/head places these extracapsular vessels at extreme risk of injury, potentially leading to avascular necrosis (AVN). Pins should ideally be placed in the center-center position to minimize this risk.

Question 1917

Topic: 4. Pediatrics

A 6-week-old female is placed in a Pavlik harness for developmental dysplasia of the hip (DDH). At her 2-week follow-up, the mother notes the child is no longer kicking her right leg. On physical exam, there is an absence of active knee extension on the right side. What is the most appropriate next step in management?

. Immediate MRI of the lumbar spine to rule out tethered cord
. Discontinue the harness completely and apply a rigid hip spica cast
. Adjust the anterior straps to decrease the amount of hip flexion
. Adjust the posterior straps to decrease the amount of hip abduction
. Continue the harness unmodified and refer to pediatric neurology

Correct Answer & Explanation

. Adjust the anterior straps to decrease the amount of hip flexion

Explanation

The infant is presenting with a femoral nerve palsy, which is the most common nerve palsy associated with the Pavlik harness. It is caused by hyperflexion of the hips, which compresses the femoral nerve against the inguinal ligament. The appropriate management is to adjust the anterior straps to decrease hip flexion, allowing the nerve to recover. Complete discontinuation is usually not necessary unless the palsy fails to resolve after adjustment. Posterior straps control abduction; hyperabduction can lead to avascular necrosis (AVN), not typically femoral nerve palsy.

Question 1918

Topic: Pediatric Hip
A 6-year-old boy presents with a painless limp. Radiographs show sclerosis and early fragmentation of the capital femoral epiphysis, consistent with Legg-Calvรฉ-Perthes disease. According to Catterall, which of the following is considered a radiographic 'head at risk' sign?
. Medial subluxation of the femoral head
. Vertical orientation of the proximal femoral physis
. A V-shaped radiolucent defect in the lateral portion of the epiphysis and adjacent metaphysis (Gage sign)
. Sclerosis of the acetabular dome
. Varus angulation of the femoral neck greater than 15 degrees

Correct Answer & Explanation

. A V-shaped radiolucent defect in the lateral portion of the epiphysis and adjacent metaphysis (Gage sign)

Explanation

Catterall described five clinical and radiographic 'head at risk' signs for Legg-Calvรฉ-Perthes disease that correlate with a worse prognosis and higher risk of femoral head deformation. These include: 1) Gage's sign (a V-shaped radiolucent defect in the lateral epiphysis/metaphysis), 2) Calcification lateral to the epiphysis, 3) Lateral (not medial) subluxation of the femoral head, 4) A horizontal (not vertical) growth plate, and 5) Metaphyseal cysts.

Question 1919

Topic: Pediatric Hip

A 13-year-old obese boy presents with 3 weeks of left groin pain and a limp. Examination reveals obligatory external rotation of the left hip during passive flexion. A radiograph is provided.

What is the recommended definitive management for a stable slipped capital femoral epiphysis (SCFE)?

. Closed reduction and spica casting
. Open reduction and internal fixation
. In situ single screw fixation
. Proximal femoral osteotomy
. Observation and non-weight bearing

Correct Answer & Explanation

. In situ single screw fixation

Explanation

A stable SCFE is characterized by the patient's ability to bear weight (with or without crutches). The standard of care for a stable SCFE is in situ fixation with a single cannulated screw placed centrally within the epiphysis. Closed reduction is contraindicated due to the high risk of avascular necrosis.

Question 1920

Topic: Pediatric Hip

A 4-month-old female infant is treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. During treatment, what is the most significant risk associated with excessive abduction of the hips in the harness?

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

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

In Pavlik harness treatment, excessive abduction of the hips places the medial circumflex femoral artery at risk of compression against the iliopsoas tendon, leading to avascular necrosis of the femoral head. Excessive flexion is associated with femoral nerve palsy.

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