A reverse bite injury (also called a clenched fist injury, or closed fist injury) is when, after one person punches another person in the face, the skin (and sometimes tendons) of his or her knuckles are cut against the teeth of the person he or she is punching. The medical treatment of this injury is similar to those of a human bite, but may also involve damage of the underlying tendons. Management may involve cutting away infected tissue, which may include tendons and therefore involve loss of use of the hand; infection also tends to spread along the tendon sheath, so that what was originally a small injury goes on to involve the entire hand.
These injuries should be managed as other human bites: wound toilet and antibiotics are essential.
If tendons or bone are visible through the wound the urgent referral to a specialist hand surgeon is mandatory, even if there is no visible damage to the tendons. Unfortunately, the nature of these injuries is such that even if the injury is optimally managed, catastrophic outcomes (loss of use of the hand, or loss of the hand) are not unusual.