Discussion
The injury rate per 100 AE was 23.6 (95% CI 20.5 to 27.0) for the Calgary dataset and is in keeping with the rate reported in a recent systematic review8 of 22.9 (95% CI 11.0 to 47.4). The injury rate per 100 AE for other combative sports is reported as 11.9–25.1 in professional boxing,17
,18–20 7.9 in taekwondo,21 7.8 in amateur boxing22 and 4.4 in judo.23 These rates only serve as a guide, as comparing MMA with other types of combative sports is difficult given the considerable methodological difference between each of these studies, of which the operational definition for an injury can be quite varied. Even if a reliable comparison was possible, it would be difficult to tease out the specific reasons for any observed differences. This is especially true given that these sports are being contested under different rules, some only allow specific types or parts of the body to be struck, others do not allow striking at all and in some protective equipment is worn. Frequencies of lacerations and soft tissue injuries (32.1%) and fractures (5.6%) are in keeping with the literature,8 although these are on the lower end of the incidence of these injuries.
The concussion rate per 100 AE was 14.7 (95% CI 11.8 to 17.2) for this study and this rate has previously been reported as 28.312 and 15.913 per 100 AE for MMA. An alternative means to represent concussion risk would be in the context of an athlete’s career. For the Calgary dataset, the concussion rate can also be reported as 0.294 concussions/contest. A similar rate can be derived for professional American football24 (0.4114 concussions/contest), Canadian junior ice hockey25 (0.4038 concussions/contest) and English professional Rugby union26 (0.1119 concussion/contest). One can estimate the number of concussions for one athlete over a 10-year career if the following assumptions are madei: the athletes play at a professional level, the total number of athletes for a team is the number of positions of play on the teamii and there are no missed games due to injury or other circumstances. With these assumptions, this would equate to the following number of career concussion over a 10 year: ice hockey (27.6), MMA (4.4), American football (2.2) and Rugby union (0.8). When viewed in the context of career risk, it appears that MMA does not confer the same exposure to concussion as seen in other popular sports. However, this simplified derivation should be viewed with caution given the assumptions that were made, since the baseline concussion per contest rates come from a diverse set of methodologically different studies, and within each of these sports there is no recognised baseline concussion rate in the literature.
Non-Canadian athletes are at a significant risk of acquiring an injury when competing in MMA contests in Calgary. It is possible that uneven matchmaking may contribute to this finding. The ABC is predominately subscribed to by American and Canadian commissions. Athletes who have competed in these jurisdictions will have the results of an event forwarded to the ABC to register suspensions and contest outcomes. For American and Canadian athletes and commissions, it is possible for an objective matchmaking process to occur. However, for athletes who are competing outside of these countries, there may not be the same pressure for commissions to provide this information to the ABC or other centralised organisation. As such, when matchmaking occurs for non-Canadian athletes in Canada it may not be an informed process if there is no information availble through the ABC.
Intuitively, matchmaker and referee were expected to influence the risk for injury and mTBI in MMA athletes. Each of these individuals plays a pivotal role, one creating contests where appropriately matched athletes compete against one another and the other ensuring a fair contest, while trying to minimise the health risks of the athletes. In the context of the CCSC data, neither matchmaker nor referee was observed as a risk factor. In part, this may be related to the CCSC overseeing the matchmaking process to ensure an evenly matched contest and requiring each referee to undertake training to obtain a minimal skill set. However, it is suggested that future studies keep these risk factors in mind when conducting their analysis since this dataset may have been biased because there was only a single dominant matchmaker and a handful of dominant experienced referees.
A recent study27 reported on the pre-bout medical screening of MMA athletes and identified 5.8% of athletes with medical reasons for termination of their bout. In this cohort, the most common reason for the match cancellation was abnormal neuroimaging, including post-traumatic gliosis, mircohaemorrhage, chronic orbital fractures and lacunar infarct. Ensuring standardised precontest medical screening prevents unsuitable athletes from participating in competition, exacerbating an existing health concern or creating a new health issue. Curran-Sills27 outlined several recommendations that included: the creation of guidelines regarding pre-bout and post-bout neuroimaging, the implementation of industry-wide minimum medical screening standards, the adoption of a longitudinal approach for weight monitoring and the development of competent ringside physician groups. Within the MMA community, there appears to be interest and will to implement some of these approaches to optimise MMA athlete health and reduce the risk of poor outcomes. Beyond these recommendations, it would be appropriate to consider more robust interventions to protect athletes engaged in amateur MMA. While others13 have recommended a ban on amateur MMA, it does not seem realistic to believe that this will be accomplished when there are many popular sports with inherent health risks that the public continue to engage in. Perhaps alternative inventions could include: restriction of those who have previously competed in an unsanctioned event from competing in a sanctioned event; the use of protective head equipment as worn in Olympic taekwondo and previously worn in Olympic boxing; limiting the types of techniques that amateur athletes are exposed too in competition; a modified form of the standing 8-count that is commonly used in boxing after a knock down; or educational programmes aimed at publicizing appropriate return-to-play guides as are actively pursued in other sports. Ultimately, it appears inappropriate to expose those engaged in amateur MMA to the same risks as would be experienced by a professional MMA athlete.