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Pediatric Upper Extremity & Spine MCQs

Practice Set 10 of 33

This practice set contains high-yield board review questions covering key concepts in Pediatric Upper Extremity & Spine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 181

Topic: Pediatric Upper Extremity & Spine
In the Bracing in Adolescent Idiopathic Scoliosis Trial (BRAIST), what factor was most strongly correlated with the prevention of curve progression to a surgical magnitude (>=50 degrees)?
. Curve pattern
. Initial Risser stage
. Dose-response hours of brace wear
. Body Mass Index (BMI)
. Initial curve magnitude

Correct Answer & Explanation

. Dose-response hours of brace wear

Explanation

The BRAIST trial demonstrated a strong dose-response relationship between brace wear and success. Patients who wore the brace for more than 12.9 hours per day had success rates exceeding 90%.

Question 182

Topic: Pediatric Upper Extremity & Spine

A 16-year-old girl undergoes a posterior spinal fusion from T4 to L3 for adolescent idiopathic scoliosis (Lenke 1A). On postoperative day 4, she develops severe bilious emesis, abdominal distension, and weight loss. Upright abdominal films show a dilated stomach and proximal duodenum with abrupt cutoff. What is the anatomic mechanism of this complication?

. Compression of the duodenum between the superior mesenteric artery and the aorta
. Postoperative paralytic ileus secondary to narcotic use
. Herniation of the bowel through a mesenteric defect
. Compression of the celiac trunk by the median arcuate ligament
. Adhesive small bowel obstruction

Correct Answer & Explanation

. Compression of the duodenum between the superior mesenteric artery and the aorta

Explanation

Superior Mesenteric Artery (SMA) syndrome is a known complication following scoliosis correction. Lengthening of the spine alters the angle of the SMA, compressing the third portion of the duodenum against the aorta.

Question 183

Topic: Pediatric Upper Extremity & Spine

A 12-year-old girl with adolescent idiopathic scoliosis has a 35-degree right thoracic curve. Her Risser stage is 1. Her menarche occurred 2 months ago. What is the most appropriate management?

. Observation with radiographs in 6 months
. Thoracolumbosacral orthosis (TLSO) bracing
. Posterior spinal fusion
. Anterior tethering
. Physiotherapy alone

Correct Answer & Explanation

. Observation with radiographs in 6 months

Explanation

In a growing child (Risser 0-2) with an AIS curve between 25 and 45 degrees, bracing is indicated to halt progression. Given her recent menarche and Risser 1 status, she has significant growth remaining, making bracing the gold standard.

Question 184

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarcheal female presents with a right thoracic curve of 32 degrees.

Radiographs show open triradiate cartilages and a Risser stage of 0. What is the most appropriate management based on the Bracing in Adolescent Idiopathic Scoliosis Trial (BrAIST)?

. Observation with radiographs in 6 months
. Physical therapy and core strengthening
. Nighttime only bending brace
. Thoracolumbosacral orthosis (TLSO) for 18 hours daily
. Posterior spinal fusion

Correct Answer & Explanation

. Observation with radiographs in 6 months

Explanation

The BrAIST study demonstrated the efficacy of bracing in preventing curve progression to the surgical threshold (>50 degrees) in patients with AIS who are still growing (Risser 0-2) with curves between 25 and 40 degrees. A dose-response curve showed optimal results with >18 hours of wear per day.

Question 185

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy presents with a completely displaced extension-type supracondylar fracture of the humerus.

Which of the following clinical deficits represents the most common nerve injury associated with this specific fracture pattern?

. Inability to cross the index and middle fingers.
. Inability to flex the interphalangeal joint of the thumb and distal interphalangeal joint of the index finger.
. Loss of sensation over the dorsal first web space.
. Weakness of wrist extension with significant radial deviation.
. Inability to extend the metacarpophalangeal joints of the fingers.

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 the most commonly injured nerve in extension-type supracondylar humerus fractures. Injury to the AIN manifests as weakness or inability to flex the interphalangeal joint of the thumb (flexor pollicis longus) and the distal interphalangeal joint of the index finger (flexor digitorum profundus), resulting in an inability to form the 'OK' sign.

Question 186

Topic: Pediatric Upper Extremity & Spine
A 5-year-old boy presents with a Gartland type III extension-type supracondylar humerus fracture. Which specific physical examination finding is the hallmark of the most common nerve injury associated with this fracture pattern?
. Inability to flex the distal interphalangeal joint of the index finger
. Inability to cross the index and middle fingers
. Inability to extend the interphalangeal joint of the thumb
. Numbness of the dorsal first web space
. Weakness of the abductor pollicis brevis

Correct Answer & Explanation

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

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. The AIN is a purely motor branch of the median nerve that innervates the flexor pollicis longus (FPL), the flexor digitorum profundus (FDP) to the index and middle fingers, and the pronator quadratus. Injury results in the inability to form an 'OK' sign, manifesting as an inability to flex the IP joint of the thumb and the DIP joint of the index finger.

Question 187

Topic: Pediatric Upper Extremity & Spine

A 5-year-old boy presents with a displaced flexion-type supracondylar humerus fracture after falling directly onto a flexed elbow. Which of the following nerve injuries is most frequently associated with this specific fracture pattern?

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

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

While extension-type supracondylar humerus fractures most commonly injure the anterior interosseous nerve (AIN), flexion-type fractures have a higher association with ulnar nerve injuries due to posterior displacement of the proximal fragment.

Question 188

Topic: Pediatric Upper Extremity & Spine

A 7-year-old girl presents with a flexion-type supracondylar humerus fracture. Her hand is well-perfused, but she exhibits a specific neurologic deficit. Which nerve is most commonly injured in this specific fracture pattern?

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

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

Unlike extension-type supracondylar fractures where the anterior interosseous nerve is most commonly injured, flexion-type supracondylar fractures place the ulnar nerve at the greatest risk of injury.

Question 189

Topic: Pediatric Upper Extremity & Spine

An 8-year-old boy presents to the emergency department with a flexion-type supracondylar humerus fracture. Which of the following nerve injuries is most frequently associated with this specific fracture configuration?

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

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

While extension-type supracondylar humerus fractures are most commonly associated with anterior interosseous nerve injuries, flexion-type fractures are classically and most frequently associated with ulnar nerve palsy.

Question 190

Topic: Pediatric Upper Extremity & Spine

Which bundle of the ulnar collateral ligament (UCL) of the elbow is the primary restraint to valgus stress during the late cocking phase of throwing, and where is its isometric origin?

. Anterior bundle, originating from the anteroinferior medial epicondyle
. Posterior bundle, originating from the posteroinferior medial epicondyle
. Transverse bundle, originating from the olecranon
. Anterior bundle, originating from the sublime tubercle
. Posterior bundle, originating from the medial supracondylar ridge

Correct Answer & Explanation

. Anterior bundle, originating from the anteroinferior medial epicondyle

Explanation

The anterior bundle of the UCL is the primary restraint to valgus stress between 30 and 120 degrees of flexion. Its isometric origin is located on the anteroinferior surface of the medial epicondyle.

Question 191

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from monkey bars and sustains an extension-type supracondylar humerus fracture. Radiographs show a Gartland Type III pattern with posteromedial displacement of the distal fragment. Which peripheral nerve is at the greatest risk of injury in this specific displacement pattern?
. Ulnar nerve
. Radial nerve
. Anterior interosseous nerve
. Posterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Radial nerve

Explanation

Posteromedial displacement of the distal fragment causes the proximal metaphyseal fragment to spike anterolaterally, placing the radial nerve at the highest risk of injury. Posterolateral displacement endangers the median nerve (or AIN).

Question 192

Topic: Pediatric Upper Extremity & Spine

According to the Lenke classification for adolescent idiopathic scoliosis, a curve is considered structurally significant and should be included in the fusion construct if the Cobb angle fails to reduce below what threshold on side-bending radiographs?

. 15 degrees
. 20 degrees
. 25 degrees
. 30 degrees
. 35 degrees

Correct Answer & Explanation

. 25 degrees

Explanation

In the Lenke classification system, a minor curve is considered structural if it does not bend down to less than 25 degrees on lateral side-bending radiographs. Structural curves must be included in the final fusion construct to maintain overall coronal balance.

Question 193

Topic: Pediatric Upper Extremity & Spine

A 14-year-old female with Adolescent Idiopathic Scoliosis (AIS) has a main thoracic curve of 55 degrees, a proximal thoracic curve of 30 degrees that bends out to 15 degrees, and a thoracolumbar curve of 40 degrees that bends out to 20 degrees. The apical lumbar vertebra is bisected by the center sacral vertical line (CSVL). The T5-T12 sagittal kyphosis is 25 degrees. What is her Lenke classification?

. Lenke 1AN
. Lenke 1BN
. Lenke 2BN
. Lenke 3BN
. Lenke 1CN

Correct Answer & Explanation

. Lenke 1BN

Explanation

The main thoracic curve is the major curve, and both minor curves bend out to < 25 degrees, making it a Type 1 (Main Thoracic). The CSVL bisecting the apical lumbar vertebra makes it a lumbar modifier B. Normal sagittal kyphosis (10 to 40 degrees) gives a sagittal modifier N, resulting in 1BN.

Question 194

Topic: Pediatric Upper Extremity & Spine

In the evaluation of Adolescent Idiopathic Scoliosis (AIS), dynamic side-bending radiographs are routinely obtained. According to the Lenke classification, a curve is defined as 'structural' if it has a residual Cobb angle of at least what magnitude on maximal side-bending?

. 10 degrees
. 15 degrees
. 20 degrees
. 25 degrees
. 30 degrees

Correct Answer & Explanation

. 25 degrees

Explanation

The Lenke classification of AIS dictates that a minor curve is considered structurally significant if it does not bend out to less than 25 degrees (i.e., residual Cobb angle is >/= 25 degrees) on dynamic side-bending radiographs or has a kyphosis >/= +20 degrees.

Question 195

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy presents with a Gartland Type III supracondylar humerus fracture. On examination, the hand is pink and well-perfused, but the radial pulse is absent. Following closed reduction and percutaneous pinning, the hand remains pink, but the pulse is still absent. What is the next best step in management?
. Immediate vascular surgery consult for open arterial exploration
. Observation and admission for close clinical monitoring
. Removal of all pins and open reduction via an anterior approach
. Performance of an upper extremity angiogram
. Application of a long arm cast in 120 degrees of flexion

Correct Answer & Explanation

. Observation and admission for close clinical monitoring

Explanation

In the setting of a pink, pulseless hand following successful reduction and pinning of a pediatric supracondylar fracture, the standard of care is close clinical observation. Open exploration is only indicated if the hand becomes pale and poorly perfused (ischemic).

Question 196

Topic: Pediatric Upper Extremity & Spine
A 5-year-old boy sustains a Gartland type III supracondylar humerus fracture. On initial presentation, the radial pulse is absent, but the hand is pink and warm. Following closed reduction and percutaneous pinning, the hand remains pink and well-perfused, but the pulse is still absent on Doppler. What is the most appropriate next step?
. Immediate open vascular exploration and repair
. CT angiography of the upper extremity
. Remove percutaneous pins and perform open reduction
. Observation and admission for close neurovascular monitoring
. Emergent volar and dorsal fasciotomies of the forearm

Correct Answer & Explanation

. Observation and admission for close neurovascular monitoring

Explanation

A 'pulseless, pink' hand after anatomic reduction of a pediatric supracondylar humerus fracture indicates adequate collateral circulation. Current guidelines recommend close inpatient observation rather than immediate vascular exploration, as the pulse typically returns over hours to days.

Question 197

Topic: Pediatric Upper Extremity & Spine

In the Lenke classification for adolescent idiopathic scoliosis (AIS), a structural proximal thoracic (PT) curve is defined by either a regional kyphosis (T2-T5) of at least +20 degrees, OR a side-bending Cobb angle of at least what magnitude?

. 10 degrees
. 15 degrees
. 20 degrees
. 25 degrees
. 30 degrees

Correct Answer & Explanation

. 20 degrees

Explanation

According to the Lenke classification system for AIS, a curve is considered structural if the Cobb angle fails to correct to less than 25 degrees on side-bending radiographs, OR if there is a regional kyphosis of at least +20 degrees.

Question 198

Topic: Pediatric Upper Extremity & Spine
In the Lenke classification system for adolescent idiopathic scoliosis (AIS), a minor curve is considered 'structural' and generally must be included in the fusion construct if it meets which of the following radiographic criteria?
. Cobb angle > 10 degrees on a standing coronal radiograph
. Cobb angle > 15 degrees on a dynamic push-prone radiograph
. Cobb angle ≥ 25 degrees on a coronal side-bending radiograph
. Apical vertebral translation > 2 cm
. Apical vertebral rotation Grade III or greater

Correct Answer & Explanation

. Cobb angle ≥ 25 degrees on a coronal side-bending radiograph

Explanation

According to the Lenke classification for AIS, a minor curve is considered structural if it fails to correct to less than 25 degrees on a coronal side-bending radiograph (i.e., Cobb angle remains ≥ 25 degrees). A regional sagittal kyphosis of ≥ +20 degrees also defines a minor curve as structural.

Question 199

Topic: Pediatric Upper Extremity & Spine

A 14-year-old female presents with adolescent idiopathic scoliosis. Radiographs demonstrate a main thoracic curve of 55 degrees, a proximal thoracic curve of 20 degrees that bends out to 15 degrees, and a thoracolumbar/lumbar curve of 35 degrees that bends out to 15 degrees. The T5-T12 kyphosis is +25 degrees. According to the Lenke classification system, what is her curve type?

. Lenke 1
. Lenke 2
. Lenke 3
. Lenke 4
. Lenke 6

Correct Answer & Explanation

. Lenke 1

Explanation

Lenke 1 is a Main Thoracic curve. The minor curves (proximal thoracic and thoracolumbar/lumbar) bend out to < 25 degrees, meaning they are non-structural. The sagittal modifier is Normal (N) because T5-T12 kyphosis is between +10 and +40 degrees. Therefore, she is a Lenke 1.

Question 200

Topic: Pediatric Upper Extremity & Spine

A 13-year-old premenarchal female (Risser stage 0) is diagnosed with adolescent idiopathic scoliosis (AIS). Her primary right thoracic curve measures 32 degrees on standing PA radiographs. According to the guidelines of the Scoliosis Research Society (SRS), what is the most appropriate next step in management?

. Observation with repeat standing radiographs in 6 months
. Prescription of a rigid thoracolumbosacral orthosis (TLSO) for 16-23 hours daily
. Prescription of a nighttime-only bending brace
. Posterior spinal fusion with segmental instrumentation
. Anterior vertebral body tethering

Correct Answer & Explanation

. Prescription of a rigid thoracolumbosacral orthosis (TLSO) for 16-23 hours daily

Explanation

According to the SRS criteria, bracing is indicated for actively growing patients (girls who are premenarchal or <1 year postmenarchal, Risser 0-2) with a primary curve measuring between 25 and 40 degrees. The standard of care, supported by the BrAIST trial, is a rigid TLSO worn for 16-23 hours a day, which significantly decreases the risk of curve progression to the surgical threshold.

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