Lateral Epicondyle Avulsion Fracture

History: child with elbow pain. 

Lateral epicondyle avulsion fracture – frontal radiograph of the left elbow reveals a fragment of bone (yellow arrow) which has been pulled from the lateral epicondyle by the common extensor tendon. Additionally, the fragment appears to be rotated laterally.

This is an example of a lateral epicondyle avulsion fracture in a child, which is a very rare epicondyle fracture and much less common than medial epicondyle fractures. A lateral epicondyle fracture is due to an avulsion of the lateral epicondyle by excessive force from the common extensor tendon, which is the shared origin of the extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris.

With the above amount of displacement and rotation of the bone fragment, open reduction internal fixation will have to be performed. In general, >5mm of displacement requires internal fixation, which will usually be done with Kirshner wires in young children and screws in older children. If improper healing occurs, varus instability can occur.

It is important to understand the sequence of ossification in the pediatric elbow to be able to correctly interpret a pediatric elbow radiograph for possible injury. See this mnemonic here for elbow ossification centers.