Sports! A mallet finger fracture of the tip of any finger usually occurs during a sporting activity. It's so common in baseball it is often called baseball finger.

The cause is usually catching a ball wrong. The tip of the finger is forced suddenly into flexion. The extensor tendon and a small piece of bone pull away from the joint. Without the tendon to extend the tip of the finger, it stays in a bent position. The finger looks like a mallet, thus the name.