An avulsion fracture occurs when an injury causes a ligament or tendon to break off (avulse) a small piece of a bone to which it is attached. Serious injury to the involved ligament or tendon may also be present.

An avulsion fracture may be caused by direct force, such as a hard tackle in football, or indirect force, such as an aggressive pivot in soccer or basketball. Small avulsion fractures are usually treated with ice and rest and rarely cause any problems, such as pain or discomfort, after the injury heals. Surgery may be needed if the bone fragment is large and widely separated from the bone and other significant tendon or ligament detachment is also present. Avulsion fractures that occur on a growth plate in young children also may require surgery.