Knee Injury in Competitive Brazilian Jiu Jitsu Athletes: Implications for Training

Background: The “heel hook” is a debilitating, high-percentage submission move in Brazilian jiu jitsu. While evidence suggests that the heel hook can result in severe ligamentous damage to the knee and/or ankle, definitive data on injuries from this technique are lacking. The purpose of this study was to assess the safety of the heel hook by comparing the incidence of knee and ankle injuries in International Brazilian Jiu Jitsu Federation (IBJJF) competitions where the move was permitted versus banned. Hypothesis: Knee and ankle injury incidence will be higher in those exposed to the heel hook relative to those not exposed to the heel hook during competition. Study Design: Cross-sectional. Level of Evidence: Level 4. Methods: Using data from 303 adult (<30 years old) and 455 masters (≥30 years old) division brown and black belt IBJJF competitors from 2021, and 164 adult brown and black belt competitors from 2009, we calculated injury frequencies, incidence rates per 1000 matches, and incidence rate ratios resulting from submission holds, emphasizing the heel hook. Results: In 2021 (heel-hook-legal), knee injury incidence rate in exposed competitors was 26.5 per 1000 matches, while knee injury incidence rate in unexposed competitors was 2.2 per 1000 matches (relative risk [RR], 12.0; 95% CI, 1.5, 96.1; P < 0.001). There was no significant difference in ankle injury incidence in exposed (19.8 injuries per 1000 matches) versus unexposed (8.8 injuries per 1000 matches) competitors. There were no significant differences in ankle or knee injury incidence when comparing injury rates between athletes in 2009 and 2021. Conclusion: Our findings indicate the heel hook significantly increased risk of knee injury. Clinical Relevance: Competitive BJJ athletes should engage in skill training to mitigate knee injury risk.