The patient injures the fingertip by falling backward and striking it on the floor or hitting it in some other way, causing sudden and forceful hyperextension at the distal interphalangeal (DIP) joint against resistance. Alternatively, this injury can befall a football player trying to tackle the ball carrier but only catching the jersey or belt with the distal phalanx of one finger (Fig. 110.1). The ring finger is especially susceptible to this injury. Both mechanisms can avulse the insertion of the flexor tendon on the distal phalanx. The patient may feel a pop, followed by immediate pain and swelling. The distal fingerpad becomes markedly swollen, often with ecchymosis. The patient is often unaware that the DIP joint cannot be actively flexed.