The patient is unable actively to extend the terminal phalange although the distal interphalangeal joint can be extended passively.This is known as-

In medicine, mallet finger, also baseball finger, dropped finger and (more generally) extensor tendon injury, is an injury of the extensor digitorum tendon of the fingers at the distal interphalangeal joint (DIP). It results from hyperflexion of the extensor digitorum tendon, and usually occurs when a ball (such as a softball, basketball, or volleyball), while being caught, hits an outstretched finger and jams it - creating a ruptured or stretched extensor digitorum tendon. Treatment options include surgery or putting the finger in a Mallet splint for 6 to 8 weeks or extension block k-wire for 4 weeks. The splint allows the tendon to return to normal length, if the finger is bent during these weeks the healing process must sta all over again. Surgery is used to reattach the tendon and is usually performed within a week of the injury.