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4. Pediatrics MCQs

Practice Set 251 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 5001

Topic: Pediatric Hip

A 4-month-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her follow-up appointment, she is noted to have decreased active extension of the left knee. The harness is removed. Which nerve is most likely compressed, and what is the primary cause?

. Sciatic nerve due to excessive abduction
. Obturator nerve due to excessive adduction
. Femoral nerve due to excessive flexion
. Lateral femoral cutaneous nerve due to poor strap padding
. Tibial nerve due to inadequate ankle positioning

Correct Answer & Explanation

. Sciatic nerve due to excessive abduction

Explanation

Femoral nerve palsy is the most common nerve palsy associated with Pavlik harness treatment and is caused by hyperflexion of the hip, causing the nerve to be compressed against the inguinal ligament. It clinically presents as a loss of active knee extension. Treatment involves immediate adjustment or temporary removal of the harness.

Question 5002

Topic: Pediatric Lower Extremity

The Ponseti method is the gold standard for the treatment of idiopathic clubfoot (talipes equinovarus). According to this technique, the serial casting process follows a specific order of deformity correction (CAVE). What is the first component of the deformity that must be corrected?

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

Correct Answer & Explanation

. Equinus

Explanation

In the Ponseti method, the deformities are corrected in a specific sequence summarized by the acronym CAVE: Cavus, Adductus, Varus, Equinus. The cavus is corrected first by elevating the first ray (supinating the forefoot) to align it with the hindfoot. Only then is the entire foot abducted around the head of the talus to correct adductus and varus.

Question 5003

Topic: 4. Pediatrics

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip. At the 2-week follow-up, the parents report that the infant is no longer actively extending the knee on the treated side. What is the most likely iatrogenic cause of this physical finding?

. Excessive abduction of the hip
. Excessive flexion of the hip
. Inadequate flexion of the hip
. Avascular necrosis of the femoral head
. Harness strap impingement on the fibular neck

Correct Answer & Explanation

. Excessive abduction of the hip

Explanation

Excessive hip flexion in a Pavlik harness can cause a transient femoral nerve palsy, resulting in decreased active knee extension. The anterior straps should be adjusted to decrease hip flexion, which usually allows the palsy to resolve spontaneously.

Question 5004

Topic: Pediatric Hip

A 13-year-old boy presents to the emergency department with acute severe hip pain and inability to bear weight after a minor fall. Radiographs demonstrate a displaced slipped capital femoral epiphysis (SCFE). According to the Loder classification, what is the most significant prognostic implication of his inability to bear weight?

. Increased risk of contralateral SCFE
. Increased risk of chondrolysis
. Increased risk of avascular necrosis (AVN)
. Decreased need for surgical fixation
. Guaranteed premature physeal closure

Correct Answer & Explanation

. Increased risk of contralateral SCFE

Explanation

The Loder classification defines a SCFE as unstable if the patient is unable to bear weight with or without crutches. Unstable SCFE carries a significantly higher risk of avascular necrosis (up to 50%) compared to stable SCFE.

Question 5005

Topic: Pediatric Lower Extremity

An infant is diagnosed with idiopathic clubfoot (talipes equinovarus) and treatment with the Ponseti method is initiated. According to this standardized casting technique, what is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Equinus, Varus, Adductus, Cavus

Explanation

The Ponseti method systematically corrects clubfoot deformities in the specific order of the acronym CAVE: Cavus, Adductus, Varus, and finally Equinus. Equinus is typically corrected last, often requiring a percutaneous Achilles tenotomy.

Question 5006

Topic: Pediatric Hip

In the management of Legg-Calve-Perthes disease, the Herring lateral pillar classification is widely used to determine prognosis. A hip where the lateral pillar of the femoral head maintains greater than 50% but less than 100% of its original height is classified as:

. Group A
. Group B
. Group B/C border
. Group C
. Group D

Correct Answer & Explanation

. Group A

Explanation

In the Herring classification, Group B indicates >50% lateral pillar height maintained. Group A has no loss of height, and Group C has <50% of the original lateral pillar height maintained.

Question 5007

Topic: Pediatric Upper Extremity & Spine
A 5-year-old boy presents with a displaced Gartland type III supracondylar humerus fracture. On examination, the hand is pink and well-perfused, but the radial pulse is absent. Which of the following is the most appropriate initial management?
. Immediate open vascular exploration with saphenous vein grafting
. Urgent CT angiography of the upper extremity
. Urgent closed reduction and percutaneous pinning
. Application of warm compresses and observation for 24 hours
. Closed reduction and application of a long arm cast in 120 degrees of flexion

Correct Answer & Explanation

. Urgent closed reduction and percutaneous pinning

Explanation

A pulseless, pink hand in a pediatric supracondylar fracture should first be managed with urgent closed reduction and percutaneous pinning. Vascular status typically normalizes once the fracture is reduced, relieving the kink or tether on the brachial artery.

Question 5008

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During follow-up, the parents report the infant has stopped kicking the affected leg. Examination reveals weakness in knee extension. This complication is most likely due to excessive positioning in which direction?

. Excessive hip extension
. Excessive hip adduction
. Excessive hip flexion
. Excessive knee flexion
. Excessive hip internal rotation

Correct Answer & Explanation

. Excessive hip extension

Explanation

Femoral nerve palsy is the most common neurologic complication associated with the Pavlik harness and is caused by excessive hip flexion compressing the nerve against the inguinal ligament. It usually resolves completely after adjusting or temporarily discontinuing the harness.

Question 5009

Topic: Pediatric Hip

A 12-year-old obese boy is diagnosed with a unilateral left-sided slipped capital femoral epiphysis (SCFE). In which of the following scenarios is prophylactic percutaneous in situ pinning of the contralateral right hip most strongly indicated?

. If the patient has a skeletal age of 14 years
. If the left SCFE is classified as acute and unstable
. If the patient has an underlying diagnosis of renal osteodystrophy or hypothyroidism
. If the patient demonstrates a mild restriction of internal rotation on the asymptomatic side
. If the patient has a body mass index (BMI) at the 85th percentile

Correct Answer & Explanation

. If the patient has a skeletal age of 14 years

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial for idiopathic cases but is strongly recommended for patients with endocrine disorders (such as hypothyroidism, panhypopituitarism) or metabolic bone diseases (like renal osteodystrophy), as well as those undergoing prior radiation therapy to the pelvis. These patients have a significantly higher risk (up to 100% in some metabolic conditions) of developing a subsequent contralateral slip compared to the general idiopathic SCFE population. Other factors favoring prophylactic pinning include younger age (open triradiate cartilage) and follow-up unreliability.

Question 5010

Topic: Pediatric Hip

A 3-month-old female is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up visit, the parents report that the child has stopped actively extending her right knee. On examination, the infant lacks active knee extension, and the patellar reflex is absent on the right. What positioning error in the Pavlik harness is the most likely cause of this complication?

. Inadequate hip abduction
. Excessive hip abduction
. Inadequate hip flexion
. Excessive hip flexion
. Excessive internal rotation of the hip

Correct Answer & Explanation

. Inadequate hip abduction

Explanation

The patient is presenting with a femoral nerve palsy, which is the most common nerve injury associated with Pavlik harness use. Femoral nerve palsy occurs secondary to excessive hip flexion, which causes compression or stretch of the femoral nerve against the inguinal ligament or the brim of the pelvis. The hallmark sign is decreased or absent active knee extension. Treatment is to loosen or temporarily remove the anterior straps to decrease hip flexion, which usually leads to spontaneous recovery. Excessive hip abduction is the risk factor for avascular necrosis (AVN) of the femoral head.

Question 5011

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy presents to the emergency department after falling from monkey bars. He has a severely displaced, completely off-ended extension-type supracondylar humerus fracture (Gartland Type III). On examination, his hand is warm and pink, capillary refill is less than 2 seconds, but there is no palpable radial pulse. What is the most appropriate next step in management?
. Immediate operative exploration of the brachial artery
. Stat CT angiography of the upper extremity
. Urgent closed reduction and percutaneous pinning in the operating room
. Application of a long arm cast in 120 degrees of flexion and close observation
. Administration of systemic thrombolytics and heparin

Correct Answer & Explanation

. Urgent closed reduction and percutaneous pinning in the operating room

Explanation

The patient has a "pink, pulseless" hand in the setting of a Gartland III supracondylar fracture. The brachial artery is frequently kinked, tethered, or placed in spasm over the proximal fracture fragment rather than completely transected. The standard of care for a pink, pulseless hand is to proceed urgently to the operating room for closed reduction and percutaneous pinning (CRPP) of the fracture. In the vast majority of cases, reduction of the fracture relieves the vascular kinking and restores the pulse. Vascular exploration is only indicated if the hand remains pulseless and becomes poorly perfused (cold/white) after successful fracture reduction and pinning.

Question 5012

Topic: 4. Pediatrics
A 3-year-old girl is evaluated for worsening bilateral genu varum. Standing radiographs demonstrate a metaphyseal-diaphyseal angle (MDA) of 18 degrees and depression of the medial tibial metaphysis with a distinct medial beak. According to the Langenskiรถld classification of infantile Blount's disease, at which stage does the proximal tibial epiphysis fuse with the metaphysis to form a frank medial physeal bar?
. Stage II
. Stage III
. Stage IV
. Stage V
. Stage VI

Correct Answer & Explanation

. Stage VI

Explanation

The Langenskiรถld classification stages the progressive radiographic changes in infantile Blount's disease. Stage VI is the final and most severe stage, characterized by complete fusion of the medial aspect of the epiphysis to the metaphysis, forming a permanent bony physeal bar that requires surgical resection and corrective osteotomy.

Question 5013

Topic: Pediatric Hip

A 12-year-old obese boy presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE) of his left hip. In which of the following clinical scenarios is prophylactic percutaneous pinning of the contralateral right hip most strongly indicated?

. Presence of an open triradiate cartilage
. Age greater than 14 years at presentation
. Underlying hypothyroidism or renal osteodystrophy
. Body mass index > 95th percentile
. A slip angle > 50 degrees on the affected side

Correct Answer & Explanation

. Presence of an open triradiate cartilage

Explanation

While prophylactic pinning of the contralateral hip in SCFE remains controversial in idiopathic cases, it is strongly indicated in patients with underlying endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency). These patients have an exceedingly high risk (often approaching 100%) of bilateral involvement.

Question 5014

Topic: Pediatric Hip

A 6-week-old infant is diagnosed with Developmental Dysplasia of the Hip (DDH) and is subsequently placed in a Pavlik harness for treatment. The treating physician must carefully adjust the straps to maintain the hips in approximately 100 degrees of flexion and safe abduction. If the anterior straps are pulled too tight, causing hyperflexion of the hips beyond 120 degrees, which of the following complications is most likely to occur?

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

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

In the application of a Pavlik harness, hyperflexion of the hips (>120 degrees) can compress the femoral nerve against the inguinal ligament, leading to an iatrogenic femoral nerve palsy (presenting as decreased quadriceps function/loss of active knee extension). Conversely, excessive forced abduction is classically associated with avascular necrosis (AVN) of the femoral head.

Question 5015

Topic: Pediatric Hip

A 6-week-old female is undergoing treatment for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up visit, the parents note she has stopped kicking her left leg. Examination reveals decreased active extension of the left knee but normal ankle movements. What is the most likely iatrogenic cause of this presentation?

. Hyperflexion of the hip in the harness
. Excessive abduction of the hip in the harness
. Ischemic necrosis of the femoral head
. Excessive adduction of the hip in the harness
. Traction injury to the sciatic nerve

Correct Answer & Explanation

. Hyperflexion of the hip in the harness

Explanation

Hyperflexion of the hip in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a femoral nerve palsy. This manifests clinically as decreased active knee extension. It is generally treated by adjusting the harness to reduce the degree of hip flexion. Excessive abduction is notoriously associated with avascular necrosis (AVN) of the femoral head, not isolated femoral nerve palsy.

Question 5016

Topic: Pediatric Hip

Which of the following patients presenting with a unilateral slipped capital femoral epiphysis (SCFE) has the strongest clinical indication for prophylactic in-situ pinning of the contralateral, asymptomatic hip?

. A 13-year-old boy with a BMI in the 99th percentile
. A 12-year-old girl with primary hypothyroidism
. A 14-year-old boy with a prior contralateral SCFE
. An 11-year-old boy with a positive family history of SCFE
. A 10-year-old girl with isolated precocious puberty

Correct Answer & Explanation

. A 13-year-old boy with a BMI in the 99th percentile

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly recommended for patients presenting with an underlying endocrine or metabolic disorder (e.g., hypothyroidism, renal osteodystrophy, growth hormone supplementation). These atypical patients have an extraordinarily high risk (approaching 100% in some series) of developing bilateral disease compared to the idiopathic adolescent population.

Question 5017

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy is brought to the emergency department after falling off monkey bars. Radiographs reveal a completely displaced extension-type supracondylar humerus fracture (Gartland Type III). On examination, the child's hand is warm and pink with brisk capillary refill, but the radial pulse is not palpable. What is the most appropriate initial management?
. Immediate open exploration of the brachial artery by vascular surgery
. Urgent closed reduction and percutaneous pinning, followed by reassessment of perfusion
. CT angiography to localize the level of vascular intimal injury prior to any intervention
. Observation for 24 hours in a splint to allow for vascular spasm resolution
. Application of a long arm cast in 120 degrees of hyperflexion to compress the fracture

Correct Answer & Explanation

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

Explanation

For a 'pulseless, pink hand' in the setting of a displaced supracondylar humerus fracture, the standard of care is urgent closed reduction and percutaneous pinning (CRPP). The pulselessness is often due to kinking, compression, or spasm of the brachial artery over the fracture fragments. Reduction usually restores flow. If the hand remains pink and well-perfused post-reduction, even without a palpable pulse, close observation is recommended over routine surgical exploration.

Question 5018

Topic: Pediatric Hip

In a patient presenting with a unilateral slipped capital femoral epiphysis (SCFE), which of the following is considered an absolute indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Age greater than 14 years
. Male sex
. Obesity (> 95th percentile BMI)
. Underlying endocrine disorder
. Moderate-to-severe slip angle (> 50 degrees) on the affected side

Correct Answer & Explanation

. Age greater than 14 years

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly indicated for patients with underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, renal osteodystrophy), patients previously treated with radiation therapy, and typically in children presenting at a young age (< 10 years). These patients have an exceptionally high risk of developing a contralateral slip.

Question 5019

Topic: Pediatric Lower Extremity

In the Ponseti method for correcting idiopathic clubfoot, what is the correct anatomical sequence of deformity correction?

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

Correct Answer & Explanation

. Equinus, Varus, Adductus, Cavus

Explanation

The Ponseti method follows a strict, step-wise sequence for clubfoot correction, easily remembered by the acronym CAVE: Cavus (corrected by elevating the first ray), Adductus, Varus (adductus and varus corrected simultaneously by abducting the midfoot with counter-pressure on the lateral head of the talus), and finally Equinus (corrected last, often requiring a percutaneous Achilles tenotomy).

Question 5020

Topic: 4. Pediatrics

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

. Immediate open reduction and arterial exploration
. Immediate CT angiography of the upper extremity
. Emergent closed reduction and percutaneous pinning
. Observation and long arm casting in situ
. Administration of systemic thrombolytics

Correct Answer & Explanation

. Immediate open reduction and arterial exploration

Explanation

In a pediatric supracondylar humerus fracture with a "pink, pulseless" hand, the initial step is emergent closed reduction and percutaneous pinning to realign the anatomy and relieve vascular kinking. Arterial exploration is generally reserved for hands that remain poorly perfused (white and pulseless) after a satisfactory reduction.

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