Review Question - QID 8912

The patient has sustained a flexion type supracondylar humerus fracture. In these patterns, the ulnar nerve is at highest risk of injury, which would manifest as weakness of the First Dorsal Interossei (FDI).

Nerve injury after Gartland III and flexion supracondylar humerus fractures follow a predictable pattern based on the direction of the displacement of the metaphyseal spike. In extension type injuries, the spike displaced anteriorly and most commonly injures the anterior interosseus nerve. In flexion type injuries, the spike moves posterior, injuring the ulnar nerve. Any supracondylar fracture with associated nerve palsy warrants urgent closed reduction and pinning.

Azbug and Herman reviewed current concepts in management of supracondylar humerus fractures. New studies suggest that most surgeons will wait 12-18 hours to address these injuries if vascular and neurological status is intact. There is a trend towards surgical management of type II injuries. Typically 2 to 3 lateral pins are used for pinning.

Babal et al. completed a meta-analysis looking at nerve injuries associated with supracondylar humerus fractures. They report an 11.3% rate of neurapraxia, with AIN injury comprising 34.1% of nerve injuries with extension type fractures and ulnar nerve injury comprising 91.3% of injuries with flexion type fractures.

Figure A is a lateral elbow radiograph showing a flexion type supracondylar humerus fracture.

Incorrect Answers:
Answer 1: Thumb extension is controlled by the posterior interosseus nerve from the radial nerve.
Answer 2: Index finger distal phalanx flexion is controlled by the anterior interosseus nerve (AIN).
Answer 3: Thumb flexion is controlled by the AIN
Answer 5: Sensation along the lateral forearm is provided by the lateral antebrachial cutaneous nerve.