Mallet finger is the term usually applied to extensor avulsion fractures. However, this entity may also be caused by distal extensor tendon ruptures. Either one results in an inability to extend the DIP joint. Mallet finger injuries are named for the resulting flexion deformity of the fingertip, which resembles a mallet or hammer. Mallet finger injuries are caused by the disruption of the extensor mechanism of the phalanx at the level of the distal interphalangeal joint, usually due to a forced flexion at the distal interphalangeal joint. This injury results in the inability to extend the distal phalanx. A mallet fracture occurs when the extensor tendon also causes avulsion of the distal phalanx. There are three subtypes of mallet fractures based on the age of the patient and the percent of the articular surface of the distal phalanx involved. The treatment remains controversial. In general, it is guided by the amount of articular surface involved in the fracture.