Involves an avulsion of the flexor digitorum profundus (FDP) tendon from its insertion on the distal phalanx.
Ring finger is most commonly involved.
Usually occurs from a grabbing attempt (resulting in forced DIP extension during maximal FDP contraction) as would occur while attempting to grab someone’s jersey such as in football or rugby.
Clinically, there is normal passive DIP ROM with loss of active flexion. Examine this by asking the patient to flex the fingertip at the DIP while the PIP joint is held in extension.
*Remember that patients with a 90% full-thickness tendon laceration may still have normal (albeit painful) range of motion. The examiner must evaluation the strength of the tendon against resistance. This injury is commonly missed as it is diagnosed as a “jammed” finger.
Plain films may show a bony avulsion, but are often negative.
Treatment is primary repair especially with large bony fragments. Partial ruptures can be treated nonoperatively at the discretion of the hand surgeon.
