Mallet finger refers to the rupture of the terminal extensor tendon at or near its attachment to the distal phalanx results in an inability to actively extend the tip of the finger.
It commonly occurs when the tip of the finger is struck by a ball, e.g., in attempting to catch a basketball or football.
Classification is important in forming an appropriate treatment plan.
Type I (most common): Closed or blunt trauma with loss of tendon continuity with or without a small avulsion fracture
Type II: Laceration at or proximal to the DIP joint with loss of tendon continuity
Type III: Deep abrasion with loss of skin, subcutaneous cover, and tendon substance
a: Transepiphyseal plate fracture in children
b: Hyperflexion injury with fracture of the articular surface
c: Hyperextension injury with fracture of the articular surface usually >50% and with early or late volar subluxation of the distal phalanx
Synonyms: Drop finger; Baseball finger
Occasionally a small avulsion fracture may be evident on X-ray and consideration should be given to surgical fixation if there is Distal interphalangeal joint subluxation.
Alternatively, treatment is with a splint that holds the Distal interphalangeal joint in extension for a period of 6 weeks.
It is very crucial that the splint be worn continuously, even in bed at night. If removed, e.g., for washing, then care should be taken to ensure that the distal phalanx is held in full extension at all times.
Splinting is effective even in injuries up to 3 months old.
Occupational therapy may benefit the patient who has a difficult time regaining flexion after the splinting is completed or the surgical Kirschner wire is removed.