"During the 635 professional MMA matches, 300 of the 1,270 athletes sustained documented injuries with an injury rate of 23.6 per 100 fight participations. Most common reported injuries were lacerations and upper extremity injuries. Severe concussion rate was 15.4 per 1,000 athlete exposures, or 3% of all matches. No deaths or critical sports-related injuries resulted from any of the regulated matches during the study period. Age, weight, and fight experience did not statistically increase the likelihood of injuries after controlling for other covariates."
The Johns Hopkins University School of Medicine Department of Emergency Medicine recently published a report of a five year study of injuries sustained during sanctioned mixed martial arts competition that took place in Nevada. The conclusion: the overall risk of critical sports-related injury appears low. Take that, haters.