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4. Pediatrics MCQs

Practice Set 45 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 881

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a displaced, extension-type supracondylar humerus fracture presenting with a pale, pulseless hand. After closed reduction and percutaneous pinning, the hand becomes well-perfused (pink) with brisk capillary refill, but the radial pulse remains absent. What is the most appropriate next step?

. Immediate vascular exploration and bypass
. Observation and close clinical monitoring
. Administration of intra-arterial vasodilators
. Removal of pins and transition to open reduction
. Perform an emergent forearm fasciotomy

Correct Answer & Explanation

. Observation and close clinical monitoring

Explanation

A "pink, pulseless" hand following the successful reduction of a supracondylar fracture indicates adequate collateral perfusion. The standard of care is close observation, as the radial pulse typically returns within several days to weeks without necessitating vascular surgery.

Question 882

Topic: Pediatric Hip

During the ultrasound evaluation of a 6-week-old infant for developmental dysplasia of the hip (DDH), the Graf classification is utilized. What anatomical landmark defines the baseline for measuring the alpha angle?

. The bony roof of the acetabulum
. The cartilaginous roof of the acetabulum
. The straight portion of the ilium
. The triradiate cartilage
. The labrum

Correct Answer & Explanation

. The straight portion of the ilium

Explanation

In the Graf ultrasound technique, the baseline is drawn along the straight portion of the ilium. The alpha angle is measured between this baseline and the bony acetabular roof line, with an angle greater than 60 degrees considered normal.

Question 883

Topic: Pediatric Hip

A 12-year-old boy with a history of panhypopituitarism presents with a stable, slipped capital femoral epiphysis (SCFE) of the left hip. What is the most appropriate management regarding the contralateral right hip?

. Prophylactic in situ pinning
. Observation with serial radiographs
. Spica casting
. Corrective osteotomy
. Epiphysiodesis

Correct Answer & Explanation

. Prophylactic in situ pinning

Explanation

Prophylactic contralateral pinning is strongly recommended in patients with SCFE associated with underlying endocrine disorders, such as panhypopituitarism or hypothyroidism, due to the extremely high risk of bilateral involvement.

Question 884

Topic: Pediatric Hip

A 6-week-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her follow-up examination, she is noted to have a new inability to actively extend her knee on the treated side. What is the most likely cause of this complication?

. Avascular necrosis of the femoral head
. Femoral nerve palsy from excessive hip flexion
. Sciatic nerve palsy from excessive hip abduction
. Obturator nerve palsy
. Ischemic contracture of the quadriceps

Correct Answer & Explanation

. Femoral nerve palsy from excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, typically caused by excessive hyperflexion of the hips compressing the nerve against the inguinal ligament. It manifests as a loss of active knee extension and usually resolves with temporary harness adjustment.

Question 885

Topic: Pediatric Hip

A 12-year-old boy presents with an acute on chronic slipped capital femoral epiphysis (SCFE) and is entirely unable to bear weight. Following in situ pinning, what is the most significant risk factor for the development of avascular necrosis (AVN) of the femoral head?

. Age greater than 10 years
. Obesity (>95th percentile)
. Unstable nature of the slip
. Bilateral presentation
. Male sex

Correct Answer & Explanation

. Unstable nature of the slip

Explanation

An unstable SCFE is defined by the inability to bear weight even with crutches. Unstable slips have a significantly higher rate of avascular necrosis (up to 50%) compared to stable slips.

Question 886

Topic: Pediatric Hip

A 6-month-old infant with developmental dysplasia of the hip (DDH) fails initial treatment with a Pavlik harness after 4 weeks. What is the next most appropriate step in management?

. Observation until 1 year of age
. Closed reduction and spica casting
. Immediate open reduction
. Femoral derotational osteotomy
. Pelvic osteotomy (Salter)

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

If a Pavlik harness fails to achieve reduction after 3 to 4 weeks in an infant, it should be discontinued to prevent "Pavlik harness disease" (posterior acetabular wear). The next step is a closed reduction and spica casting under anesthesia.

Question 887

Topic: Pediatric Hip

A 12-year-old obese male presents with left groin pain and an obligatory external rotation of the hip during passive flexion. Which of the following is an absolute indication for open reduction and internal fixation of this condition rather than in-situ pinning?

. Stable SCFE with a slip angle > 50 degrees
. Unstable SCFE with an inability to bear weight
. Bilateral SCFE
. There is no absolute indication for open reduction over in-situ pinning
. Presence of a metaphyseal blanch sign of Steel

Correct Answer & Explanation

. There is no absolute indication for open reduction over in-situ pinning

Explanation

In-situ pinning remains the gold standard for both stable and unstable Slipped Capital Femoral Epiphysis (SCFE) to minimize the risk of osteonecrosis. Open reduction (e.g., modified Dunn procedure) is controversial and not considered an absolute indication.

Question 888

Topic: Pediatric Lower Extremity

In the Ponseti method for the treatment of idiopathic clubfoot, what is the final component of the deformity to be corrected before proceeding with an Achilles tenotomy?

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

Correct Answer & Explanation

. Equinus

Explanation

The Ponseti method addresses deformities in a specific sequence: Cavus, Adductus, Varus, and finally Equinus (CAVE). A percutaneous Achilles tenotomy is frequently performed at the end to correct residual equinus contracture.

Question 889

Topic: Pediatric Hip

A 13-year-old obese boy undergoes in-situ percutaneous pinning for a stable slipped capital femoral epiphysis (SCFE). He presents 6 months later with worsening hip stiffness and pain. Radiographs demonstrate joint space narrowing and subchondral cyst formation but no avascular necrosis. What is the most likely diagnosis?

. Chondrolysis
. Avascular necrosis
. Hardware failure
. Septic arthritis
. Femoroacetabular impingement

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a known complication of SCFE, characterized by progressive loss of articular cartilage and joint stiffness. It is associated with unrecognized intra-articular pin penetration, though it can occur idiopathically in the setting of the disease itself.

Question 890

Topic: Pediatric Hip

An infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the infant is noted to have an absent spontaneous quadriceps contraction and decreased active knee extension. Which of the following harness adjustments is required?

. Increase the flexion straps
. Decrease the flexion straps
. Increase the abduction straps
. Decrease the abduction straps
. Discontinue the harness entirely and cast immediately

Correct Answer & Explanation

. Decrease the flexion straps

Explanation

The clinical presentation is consistent with a femoral nerve palsy, a known complication caused by hyperflexion of the hips in the Pavlik harness. The most appropriate immediate management is to decrease the tension on the anterior flexion straps to alleviate nerve compression.

Question 891

Topic: 4. Pediatrics

A 6-year-old boy presents with a displaced extension-type supracondylar humerus fracture. After closed reduction and percutaneous pinning, the radial pulse remains absent, but the hand is warm, pink, and has capillary refill of less than 2 seconds. What is the most appropriate next step in management?

. Immediate vascular surgery consultation for bypass
. Exploration of the brachial artery via an anterior approach
. Observation and admission for frequent neurovascular checks
. Removal of the pins and open reduction
. Perform a sympathetic nerve block

Correct Answer & Explanation

. Observation and admission for frequent neurovascular checks

Explanation

A "pink, pulseless" hand following reduction and pinning of a pediatric supracondylar humerus fracture is generally treated with close observation. Unless the hand becomes ischemic, routine surgical exploration of the artery is not indicated.

Question 892

Topic: Pediatric Hip

In a 12-year-old child diagnosed with a unilateral slipped capital femoral epiphysis (SCFE), which of the following is an absolute indication for prophylactic in situ pinning of the contralateral hip?

. Male gender
. African American ethnicity
. Presentation with chronic hip pain
. Concurrent diagnosis of hypothyroidism
. Body mass index in the 90th percentile

Correct Answer & Explanation

. Concurrent diagnosis of hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly indicated in patients with underlying endocrinopathies, such as hypothyroidism, or renal failure. These metabolic conditions carry a significantly higher risk of bilateral involvement compared to idiopathic cases.

Question 893

Topic: Pediatric Lower Extremity

In the Ponseti method for the treatment of idiopathic clubfoot, what is the correct sequential order of deformity correction?

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

Correct Answer & Explanation

. Cavus, Varus, Adductus, Equinus

Explanation

The Ponseti method utilizes the CAVE sequence: Cavus (by elevating the first ray), Adductus, Varus, and finally Equinus (which often requires a percutaneous Achilles tenotomy).

Question 894

Topic: 4. Pediatrics

A 6-year-old boy presents with a completely displaced extension-type supracondylar humerus fracture. On examination, he is unable to flex the interphalangeal joint of his thumb and the distal interphalangeal joint of his index finger. What is the most likely injured nerve?

. Anterior interosseous nerve
. Ulnar nerve
. Radial nerve
. Posterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The anterior interosseous nerve (AIN) is a motor branch of the median nerve that innervates the FPL, FDP to the index/middle fingers, and pronator quadratus. It is the most commonly injured nerve in extension-type pediatric supracondylar humerus fractures.

Question 895

Topic: Pediatric Hip



A 13-year-old obese male is diagnosed with a stable slipped capital femoral epiphysis (SCFE) of the left hip. Under what circumstance is prophylactic pinning of the contralateral right hip most strongly indicated?

. The patient has a positive family history of SCFE.
. The patient has underlying renal osteodystrophy.
. The patient is pre-menarchal.
. The slipped hip is classified as severe (slip angle > 50 degrees).
. The patient has a BMI over 30.

Correct Answer & Explanation

. The patient has underlying renal osteodystrophy.

Explanation

Prophylactic pinning of the contralateral hip is highly recommended in patients with endocrine disorders (e.g., hypothyroidism) or metabolic bone diseases (e.g., renal osteodystrophy). These underlying conditions significantly increase the risk of bilateral and sequential involvement.

Question 896

Topic: Pediatric Hip

Which of the following is an accepted indication for prophylactic in situ pinning of the contralateral asymptomatic hip in a patient presenting with an acute slipped capital femoral epiphysis (SCFE)?

. Age over 14 years
. Male gender
. Underlying endocrine disorders (e.g., hypothyroidism)
. Obesity alone (>95th percentile BMI)
. Presentation with a chronic slip

Correct Answer & Explanation

. Underlying endocrine disorders (e.g., hypothyroidism)

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended for patients with endocrinopathies (like hypothyroidism or renal osteodystrophy) or prior radiation therapy. These patients have an exceptionally high risk of bilateral involvement.

Question 897

Topic: Pediatric Lower Extremity

According to the Ponseti method for the treatment of idiopathic clubfoot, what is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Varus, Adductus, Equinus

Explanation

The Ponseti method sequentially corrects the CAVE deformities: Cavus (by elevating the first ray), Adductus, Varus, and finally Equinus. Equinus correction frequently requires a percutaneous Achilles tenotomy.

Question 898

Topic: Pediatric Hip

A 4-week-old female infant is diagnosed with developmental dysplasia of the hip (DDH) and placed in a Pavlik harness. Two weeks later, she presents with decreased active extension of her knee, though she still kicks her foot. What complication has most likely occurred?

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

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of extreme hyperflexion in a Pavlik harness, presenting as an inability to actively extend the knee. The harness should be adjusted to decrease the degree of hip flexion or temporarily discontinued.

Question 899

Topic: 4. Pediatrics

A 6-year-old child sustains a completely displaced extension-type supracondylar fracture of the humerus. Examination reveals inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. Which nerve is most likely injured?

. Anterior interosseous nerve
. Posterior interosseous nerve
. Ulnar nerve
. Superficial radial nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. It innervates the flexor pollicis longus and flexor digitorum profundus to the index and middle fingers.

Question 900

Topic: Pediatric Hip

A 3-month-old girl has a persistent dislocated hip after 4 weeks of Pavlik harness treatment for developmental dysplasia of the hip. What is the most appropriate next step in management?

. Continue Pavlik harness for an additional 4 weeks
. Perform a femoral derotation osteotomy
. Abandon the Pavlik harness and proceed to closed reduction and spica casting
. Immediate open reduction and capsulorrhaphy

Correct Answer & Explanation

. Abandon the Pavlik harness and proceed to closed reduction and spica casting

Explanation

Continuing a Pavlik harness in a persistently dislocated hip beyond 3 to 4 weeks risks 'Pavlik disease' (acetabular damage and avascular necrosis). The harness should be abandoned and the child scheduled for closed reduction and spica casting.

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