Mixed martial arts (MMA) is growing in popularity, but a lack of reliable data means that the rate and potential risk of traumatic brain injury remain unknown.
Researchers at St Michael’s Hospital in Toronto, Canada, recently reviewed 18 studies involving a total of 7,587 patients, examining head injuries in MMA fighting and published between 1990 and 2016.
Their findings have been published online in the journal Trauma.
“Currently, there is little known regarding the incidence, risk factors or possible long-term neurological effects of head injuries sustained in MMA fighting, and only low-quality observational research has been done on this topic,” said Dr Joel Lockwood, an emergency physician at St Michael’s and lead author of the review.
Across the 18 studies there was no consistent, medically accepted term for head injury suffered, but the review found that “technical knockouts”, which occur when the referee stops a fight or when an injury is severe enough a participant can no longer defend themselves, and “knockouts”, when a participant is knocked unconscious from strikes or kicks, occurred at a rate ranging between 28.3% and 46.2% of all matches. Other studies showed a lifetime average of 6.2 technical knockouts or knockouts in a career.
The review also suggested that a significant number of fights ended due to repeated strikes to the head, leaving the losing participant partially or completely unresponsive. One study included in the review reported an average of 18.5 strikes to the head in the seconds preceding complete unresponsiveness amongst professional MMA athletes, the authors said.
However, the studies were primarily observational and used inconsistent reporting methods, and no information was available regarding long-term follow-up of injured athletes.
As a result, it was impossible to define potential risk factors — including gender, age, head injury history, total number of matches in a career or professional status of MMA fighters — with any level of certainty.
The lack of high-quality data also makes it difficult to compare the incidence or severity of head injuries sustained in MMA to other contact sports.
“Larger studies and stringent medical oversight are needed to improve the management and understanding of mixed martial arts head injuries, with implementation of harm reduction strategies and/or rule modifications to prevent long-term neurological sequelae,” the researchers concluded.