A Jersey finger is a traumatic rupture of the
flexor digitorum profundus (FDP) tendon at its point of attachment to the
distal phalanx. This injury often occurs in
American football when a player grabs another player's
jersey with the tips of one or more fingers while that player is pulling or running away. The force of this action
hyperextends the tip of the finger at the DIP joint while the proximal portion of the finger is
flexed. This action can partially or completely
rupture the FDP tendon at or near its attachment point on the distal phalanx. Sometimes, the force is great enough to pull off or
avulse a piece of phalangeal bone to which the tendon can remain attached. Although it is a common football injury, this injury can occur during other sports or activities as well. After the injury occurs, the torn FDP tendon may retract slightly, remaining in the finger near the PIP joint, or can retract more fully into the palm of the hand. A person who suffers a jersey finger injury in which the FDP tendon is completely ruptured cannot flex the affected digit at the DIP joint without assistance. ==Anatomy==