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Pediatric Upper Extremity & Spine MCQs

Practice Set 33 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 641

Topic: Pediatric Upper Extremity & Spine

Which of the following is the most effective bracing technique for an adolescent with idiopathic scoliosis with a Cobb angle of 28 degrees and Risser 0-1 (skeletally immature)?

. Soft thoracolumbosacral orthosis (TLSO)
. Dynamic scoliosis brace (e.g., SpineCor)
. Milwaukee brace (cervicothoracolumbosacral orthosis)
. Nighttime-only bracing with a rigid TLSO
. Observation only

Correct Answer & Explanation

. Nighttime-only bracing with a rigid TLSO

Explanation

For skeletally immature adolescents with idiopathic scoliosis (Risser 0-1) and a Cobb angle between 20-40 degrees, bracing is indicated to prevent curve progression. While full-time rigid TLSOs are traditional, recent evidence and guidelines support the efficacy of nighttime-only bracing with a rigid TLSO for similar outcomes, improving patient compliance and quality of life. Soft braces or dynamic braces have not shown superior efficacy. The Milwaukee brace is rarely used now due to its bulkiness and cosmetic issues, reserved for very high thoracic curves. Observation only is inappropriate for a progressive curve in an immature patient.

Question 642

Topic: Pediatric Upper Extremity & Spine
A 5-year-old girl sustains a Gartland type III extension-type supracondylar humerus fracture with posterolateral displacement of the distal fragment. Upon evaluation, she cannot make a forceful 'A-OK' sign. Which nerve is most likely injured?
. Ulnar nerve
. Radial nerve
. Anterior interosseous nerve
. Musculocutaneous nerve
. Posterior interosseous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

Posterolateral displacement of the distal fragment in an extension-type supracondylar humerus fracture places the medial structures at risk, specifically the median nerve and its anterior interosseous nerve (AIN) branch. The AIN innervates the FPL and FDP to the index finger, required to make the 'A-OK' sign.

Question 643

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a supracondylar humerus fracture. Which of the following physical examination findings is most characteristic of the most common nerve palsy associated with this injury?

. Inability to extend the wrist
. Inability to flex the interphalangeal joint of the thumb
. Decreased sensation over the dorsal first web space
. Inability to abduct the fingers
. Decreased sensation over the volar tip of the index finger

Correct Answer & Explanation

. Inability to flex the interphalangeal joint of the thumb

Explanation

Correct Answer: BThe most common nerve palsy seen with supracondylar humerus fractures is a neurapraxia of the anterior interosseous branch of the median nerve (AIN). The AIN innervates the flexor pollicis longus, the flexor digitorum profundus to the index and middle fingers, and the pronator quadratus. A palsy results in the inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. It is a purely motor nerve, so sensation remains intact. Nearly all cases resolve spontaneously without surgical intervention.

Question 644

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a displaced supracondylar humerus fracture. Post-reduction, he is unable to flex the interphalangeal joint of his thumb. While this specific deficit represents the most common nerve palsy associated with this injury, which of the following nerve injuries is the second most common nerve palsy associated with this fracture pattern?

. Ulnar nerve
. Radial nerve
. Median nerve (main trunk)
. Anterior interosseous nerve
. Posterior interosseous nerve

Correct Answer & Explanation

. Radial nerve

Explanation

Correct Answer: BThe patient's inability to flex the interphalangeal joint of the thumb indicates a neurapraxia of the anterior interosseous branch of the median nerve (AIN). AIN palsy is the most common nerve palsy seen with supracondylar humerus fractures in children. This is followed closely by radial nerve palsy, making it the second most common. Nearly all cases of neurapraxia following supracondylar humerus fractures resolve spontaneously without the need for surgical exploration.

Question 645

Topic: Pediatric Upper Extremity & Spine

A 6-year-old girl sustains an extension-type supracondylar humerus fracture. Which of the following physical examination findings is most indicative of the most common nerve injury associated with this fracture pattern?

. Inability to extend the metacarpophalangeal joints
. Inability to flex the interphalangeal joint of the thumb and distal interphalangeal joint of the index finger
. Decreased sensation over the dorsal first web space
. Weakness of the dorsal interossei
. Inability to cross the index and middle fingers

Correct Answer & Explanation

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

Explanation

Correct Answer: BThe anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. It is a motor branch of the median nerve that innervates the flexor pollicis longus, the flexor digitorum profundus to the index and middle fingers, and the pronator quadratus. Injury results in the inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger (making an 'A-OK' sign). Most of these injuries represent a neurapraxia and resolve spontaneously without surgical intervention.

Question 646

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains an extension-type Gartland III supracondylar humerus fracture. On examination, he cannot flex his thumb interphalangeal joint or the distal interphalangeal joint of his index finger. Which structure is most likely injured?
. Anterior interosseous nerve
. Median nerve proper
. Radial nerve
. Posterior interosseous nerve
. Ulnar nerve

Correct Answer & Explanation

. Median nerve proper

Explanation

The inability to make an 'OK sign' (flexion of thumb IP and index DIP joints) indicates an injury to the anterior interosseous nerve (AIN). AIN palsy is the most common neurologic deficit associated with extension-type supracondylar humerus fractures.

Question 647

Topic: Pediatric Upper Extremity & Spine

A 5-year-old boy falls from monkey bars and sustains a significantly displaced extension-type supracondylar humerus fracture. On evaluation in the emergency department, his hand is warm and pink, but the radial pulse is absent. What is the most appropriate next step in management?

. Immediate CT angiography of the upper extremity
. Open exploration of the brachial artery
. Observation and elevation with cast application
. Urgent closed reduction and percutaneous pinning
. Immediate volar fasciotomy of the forearm

Correct Answer & Explanation

. Urgent closed reduction and percutaneous pinning

Explanation

In a "pink, pulseless" hand associated with a supracondylar humerus fracture, the collateral circulation is intact. The most appropriate next step is urgent closed reduction and percutaneous pinning, which frequently restores the radial pulse by relieving arterial kinking.

Question 648

Topic: Pediatric Upper Extremity & Spine

A 14-year-old girl with adolescent idiopathic scoliosis (AIS) has a proximal thoracic curve of 20 degrees (bends to 10 degrees), a main thoracic curve of 55 degrees (bends to 20 degrees), and a thoracolumbar curve of 30 degrees (bends to 15 degrees). Based on the Lenke classification system, what is her curve type?

. Type 1 (Main Thoracic)
. Type 2 (Double Thoracic)
. Type 3 (Double Major)
. Type 4 (Triple Major)
. Type 5 (Thoracolumbar/Lumbar)

Correct Answer & Explanation

. Type 1 (Main Thoracic)

Explanation

In the Lenke classification, a Type 1 curve is defined by a structural main thoracic curve, while the proximal thoracic and thoracolumbar curves are non-structural (bend out to <25 degrees). Since only her main thoracic curve is structural, she has a Type 1 curve.

Question 649

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy presents with a pink, pulseless hand following a Gartland type III supracondylar humerus fracture. After careful closed reduction and percutaneous pinning, the hand remains pink but pulseless. A Doppler ultrasound confirms biphasic flow in the palmar arch. What is the most appropriate next step in management?
. Immediate vascular exploration
. Observation and hospital admission for serial exams
. Local intra-arterial infusion of papaverine
. Removal of pins and immediate open reduction
. Prophylactic anterior compartment fasciotomy

Correct Answer & Explanation

. Observation and hospital admission for serial exams

Explanation

In a pink, pulseless hand after adequate reduction of a supracondylar humerus fracture, observation is indicated because collateral circulation is sufficient. Vascular exploration is only required if the hand remains white and pulseless after fracture reduction.

Question 650

Topic: Pediatric Upper Extremity & Spine
A 5-year-old boy falls from monkey bars and presents with a swollen, painful left elbow. Radiographs reveal an extension-type Gartland III supracondylar humerus fracture with posterolateral displacement of the distal fragment. Which of the following nerve injuries is most likely to be associated with this specific fracture pattern, and what is the corresponding clinical finding?
. Anterior interosseous nerve; inability to flex the interphalangeal joint of the thumb and distal interphalangeal joint of the index finger
. Radial nerve; inability to extend the wrist and fingers
. Ulnar nerve; inability to cross the index and middle fingers
. Median nerve (main trunk); decreased sensation over the thenar eminence
. Musculocutaneous nerve; weakness in elbow flexion

Correct Answer & Explanation

. Anterior interosseous nerve; inability to flex the interphalangeal joint of the thumb and distal interphalangeal joint of the index finger

Explanation

In extension-type supracondylar humerus fractures, the direction of displacement of the distal fragment dictates the structures at risk. Posterolateral displacement of the distal fragment causes the proximal fragment to displace anteromedially, putting the median nerve—specifically its anterior interosseous nerve (AIN) branch—at the greatest risk. The AIN is a purely motor 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 make an 'A-OK' sign. Posteromedial displacement of the distal fragment puts the radial nerve at risk. Flexion-type fractures put the ulnar nerve at risk.

Question 651

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from the monkey bars and sustains a Gartland type III extension-type supracondylar humerus fracture. Radiographs demonstrate that the distal fragment is displaced posteromedially. Based on this specific displacement pattern, which nerve is at the highest risk of injury?
. Anterior interosseous nerve
. Radial nerve
. Ulnar nerve
. Musculocutaneous nerve
. Axillary nerve

Correct Answer & Explanation

. Radial nerve

Explanation

In extension-type supracondylar humerus fractures, the direction of displacement of the distal fragment dictates the structures at risk. When the distal fragment is displaced posteromedially, the proximal fragment is driven anterolaterally, putting the radial nerve at the greatest risk of tethering or injury. Conversely, if the distal fragment is displaced posterolaterally, the proximal fragment is driven anteromedially, placing the anterior interosseous nerve (AIN) and the brachial artery at greatest risk. The AIN is the most commonly injured nerve overall in extension-type supracondylar fractures. Ulnar nerve injuries (Option C) are most commonly associated with flexion-type supracondylar fractures or iatrogenic injury from medial pin placement during operative fixation.

Question 652

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains an extension-type supracondylar humerus fracture with posterolateral displacement of the distal fragment. Based on the typical displacement pattern, which of the following physical exam findings is most likely to be present if the most commonly associated nerve injury occurred?

. Inability to flex the distal interphalangeal joint of the index finger
. Inability to extend the metacarpophalangeal joints
. Numbness over the dorsal web space of the hand
. Inability to cross the index and middle fingers
. Weakness in wrist extension with radial deviation

Correct Answer & Explanation

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

Explanation

Correct Answer: Inability to flex the distal interphalangeal joint of the index fingerIn extension-type supracondylar humerus fractures, the direction of distal fragment displacement dictates the nerve most at risk. Posterolateral displacement of the distal fragment causes the proximal fragment to displace anteromedially, putting the median nerve (specifically the anterior interosseous nerve, AIN) at greatest risk. The AIN innervates the flexor pollicis longus (FPL) and the flexor digitorum profundus (FDP) to the index and middle fingers. An AIN palsy presents as an inability to flex the IP joint of the thumb and the DIP joint of the index finger (making an 'A-OK' sign is impossible). Posteromedial displacement puts the radial nerve at risk.

Question 653

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a widely displaced extension-type supracondylar humerus fracture after falling from the monkey bars. Which of the following physical examination findings is most indicative of the most commonly associated nerve injury in this specific fracture pattern?

. Inability to extend the metacarpophalangeal joints
. Loss of sensation over the dorsal first web space
. Inability to flex the distal interphalangeal joint of the index finger
. Weakness in finger abduction and adduction
. Loss of sensation over the volar aspect of the small finger

Correct Answer & Explanation

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

Explanation

Correct Answer: Inability to flex the distal interphalangeal joint of the index fingerThe median nerve, specifically its anterior interosseous nerve (AIN) branch, is the most commonly injured nerve in extension-type supracondylar humerus fractures. The AIN is a pure motor nerve that innervates the flexor pollicis longus (FPL), the pronator quadratus, and the flexor digitorum profundus (FDP) to the index and middle fingers. Injury results in the inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger (loss of the 'A-OK' sign).

Question 654

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a widely displaced extension-type supracondylar humerus fracture after falling from monkey bars. Upon presentation, he has a pulseless, pink hand and is unable to make an 'OK' sign with his thumb and index finger. Which of the following neural structures is most likely injured?

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

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

Correct Answer: CThe anterior interosseous nerve (AIN), a motor branch of the median nerve, is the most frequently injured nerve in extension-type supracondylar humerus fractures. The AIN innervates the flexor pollicis longus (FPL), the flexor digitorum profundus (FDP) to the index and middle fingers, and the pronator quadratus. Injury to the AIN results in the inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger, leading to an inability to form the 'OK' sign. The ulnar nerve is more commonly injured in flexion-type supracondylar fractures or iatrogenically during medial pin placement.

Question 655

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy falls from monkey bars and sustains a widely displaced extension-type supracondylar humerus fracture. On physical examination, he is unable to flex the interphalangeal joint of his thumb and the distal interphalangeal joint of his index finger. Which of the following nerves is most likely injured?

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

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

Correct Answer: Anterior interosseous nerveThe anterior interosseous nerve (AIN), a pure motor branch of the median nerve, is the most commonly injured nerve in extension-type supracondylar humerus fractures. The AIN innervates the flexor pollicis longus (FPL), the flexor digitorum profundus (FDP) to the index and middle fingers, and the pronator quadratus. Injury is clinically assessed by asking the patient to make an "OK" sign; an inability to flex the IP joint of the thumb and the DIP joint of the index finger results in a "pincer" grasp instead, indicating AIN palsy. Ulnar nerve injuries are more commonly associated with flexion-type supracondylar fractures or iatrogenic injury during medial pin placement.

Question 656

Topic: Pediatric Upper Extremity & Spine

A newborn has bilateral radially deviated hands and shortened forearms. Radiographs show bilateral absent radii. On physical examination, the thumbs are present and morphologically normal. Which underlying hematologic abnormality is most closely associated with this specific presentation?

. Aplastic anemia
. Thrombocytopenia
. Leukemia
. Sickle cell trait
. Hemophilia A

Correct Answer & Explanation

. Thrombocytopenia

Explanation

Thrombocytopenia Absent Radius (TAR) syndrome is distinguished from other radial longitudinal deficiencies (like Fanconi anemia) by the presence of a normal thumb. It is associated with severe, often transient, thrombocytopenia in infancy.

Question 657

Topic: Pediatric Upper Extremity & Spine
A newborn is evaluated for bilateral absent thumbs and severe radial longitudinal deficiency. Which genetic condition should be suspected, and what specific systemic screening is indicated?
. TAR syndrome; complete blood count
. Holt-Oram syndrome; echocardiogram
. VACTERL association; renal ultrasound
. Fanconi anemia; chromosomal breakage test
. Diamond-Blackfan anemia; bone marrow biopsy

Correct Answer & Explanation

. Holt-Oram syndrome; echocardiogram

Explanation

Holt-Oram syndrome (TBX5 mutation) is characterized by upper limb anomalies, notably absent or hypoplastic thumbs, along with congenital heart defects like atrial septal defects. The absence of thumbs clearly distinguishes it from TAR syndrome, where the thumbs are classically present.

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