Mallet finger occurs when you cannot straighten your finger. And even if you try to bend the finger, the tip of the finger remains bent toward your palm. Mallet finger is the most common injury in athletes. If a mallet finger is left untreated, it may develop a deformity of the finger joints called a swan neck deformity. And the swan-neck deformity can impair the normal function of the fingers. Wearing a splint on your finger to keep it straight is the most common treatment for mallet finger.