Avulsion is simply the pulling or cutting away of something. In podiatric terminology we have two main uses for this term. First dealing with a fracture of a bone. Implying that a portion of bone was forced away from the main body of the bone. This can occur on any bone where a tendon or muscle is attached. If this pull of the tendon is stronger than the bone, then the bone will give way to form the fracture. A very common example is a 5th metatarsal base fracture where the peroneus brevis tendon attaches and the bone is weaker.
A second example of an avulsion is a term used when debriding of cutting of a toenail. Occasionally a toenail maybe infected or ingrown and a procedure is completed to remove the border of the nail. This occasionally requires an anesthetic. If the procedure is done without destroying the nail matrix, this is called a simple nail avulsion.