WBR0125

Author	Mahmoud Sakr M.D.
Exam Type	USMLE Step 2 CK
Main Category	Surgery
Sub Category	Surgery
Prompt	18 y/o male presents to the ED with severe pain in his right arm after he slipped and fell down the stairs at home. His right arm is swollen and extremely tender on palpation especially above his elbow. His vital signs were unremarkable. An X-ray was ordered by the ED physician and it shows a supracondylar fracture. Which of the following structures will be most likely injured in this case:
Answer A	Anterior interosseous nerve
Answer A Explanation	The most common complication of a supracondylar fracture is neurovascular injuries (8-21% of cases) with palsy to the anterior interosseus nerve being most common. It presents as inability to flex the interphalangeal joint of his thumb and the distal interphalangeal joint of his index finger (can't make A-OK sign).
Answer B	Brachial artery
Answer B Explanation	Also a common complication of this fracture, but neuopraxias are more common. It presents as cold, pale, and pulseless hand. long term complication can lead to Volkmann's contracture, also known as Volkmann's ischaemic contracture, which is a permanent flexion contracture of the hand at the wrist, resulting in a claw-like deformity of the hand and fingers.
Answer C	Median nerve
Answer C Explanation	Usually the AIN which is a branch of the median nerve that's injured.
Answer D	Ulnar nerve
Answer D Explanation	Ulnar nerve palsy is rarely seen with flexion-type injury patterns.
Answer E	Radial nerve
Answer E Explanation	Radial nerve palsy is the second most common neuropraxia (close second).
Right Answer	A
Explanation	The most common complication of a supracondylar fracture is neurovascular injuries (8-21% of cases) as reported in some studies. Palsy to the anterior interosseus nerve at time of injury is most common, followed by brachial artery injuries. Injury to the ulnar nerve is reported as well, but it is less common. Brachial artery injury is also a common complication of this fracture, but neuopraxias are more common. It presents as cold, pale, and pulseless hand. long term complication can lead to Volkmann's contracture, also known as Volkmann's ischaemic contracture, which is a permanent flexion contracture of the hand at the wrist, resulting in a claw-like deformity of the hand and fingers. Radial nerve palsy is the second most common neuropraxia (close second). Educational Objective: References:
Approved	Yes
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