A new recreational mechanism for the boxer's knuckle: cause for concern?

Traumatic injuries of the metacarpophalangeal joints are a common occurrence in professional and recreational sports such as boxing and martial arts, especially the fourth and fifth metacarpals. Injury usually results from a forceful impact with a clenched fist. The spectrum of injuries varies from simple skin laceration to extensor mechanism disruption, dorsal capsule rupture, metacarpal fractures and carpometacarpal joint injuries. These injuries are well documented in boxers as well as in patients who had been involved in fights and assaults. We report on two patients sustaining similar injuries to the dorsum of the hand but following punching of a recreational 'punching machine'. We describe the patterns of injury encountered and summarise the treatment. For clinical and safety reasons as well as the potential medicolegal implications, we believe it is important to highlight this mechanism of injury.