Supracondylar elbow fractures are the most common fracture of the elbow in children. The injury typically occurs after falling on an outstretched arm with a hyperextended elbow. The force pushes the olecranon into the olecranon fossa, which can fracture the distal humerus with anterior displacement. Neurovascular injury can occur as a result of fracture displacement. Nerve injury occurs in 7% of fractures and significant vascular injury occurs in 1% of supracondylar elbow fractures.1,2
The most commonly injured nerve in supracondylar humerus fracture is the median nerve, specifically the branch of the anterior interosseous nerve (AIN). The nerve can be torn or stretched when the proximal fracture fragment comes in contact with the nerve as it displaces medially. The AIN branches from the median nerve 4 cm distal to the medial epicondyle and runs in front of the interosseous membrane of the forearm. The motor function of the AIN includes the radial half of the flexor digitorum profundus, flexor pollicis longus, and pronator quadratus. The AIN can be tested by flexing the thumb interphalangeal joint with the distal interphalangeal joint of the index finger, which forms an “A-OK” sign. The ulnar nerve is the most commonly injured nerve during reduction and medial pinning of the fracture. A radial nerve injury presents as the inability to extend the wrist and digits. Quick motor tests for pediatric elbow fractures may include having the patient make an “A-OK” sign, give a thumbs up, and spread the fingers apart, which tests the median, radial, and ulnar nerves, respectively.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).
- Beaty JH, Kasser JR. Rockwood and Wilkins’ Fractures in Children. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.
- Sheth U, Souder C. Supracondylar fracture—pediatric. http://www.orthobullets.com/pediatrics/4007/supracondylar-fracture–pediatric Accessed October 31, 2016.