ACL Tears in the National Football League From 2013 to 2020: Analysis of the 2020 Season After Delays and Schedule Changes From the Early COVID-19 Pandemic Relative to Prior Seasons

BACKGROUND: The impact of fatigue and preseason preparation on anterior cruciate ligament (ACL) tears in the National Football League (NFL) are not well described. The 2020 NFL season did not include the standard preseason in response to changes secondary to the coronavirus disease-2019 (COVID-19) pandemic. PURPOSE: To evaluate the association of game play on ACL tears in NFL athletes and to determine if differences in ACL tear epidemiology were present based on season of play from 2013 to 2020. STUDY DESIGN: Descriptive epidemiology study. METHODS: ACL tears in NFL athletes were identified using publicly available data. Games played and snap counts at the time of injury were recorded for each athlete sustaining game-related injuries. Tear rates were determined, and injuries were also calculated per 1000 athlete-exposures. Incidence rate ratios (IRRs) with 95% confidence intervals (CIs) were calculated. RESULTS: Overall, 379 ACL tears were identified, including 256 (67.6%) during game play and 118 (31.1%) during practice. Practice-based injuries were significantly higher in the preseason versus the remainder of the season. Games and snaps at the time of injury did not differ by year. The incidence rate of preseason injuries was significantly greater relative to in-season injuries (IRR = 2.68; 95% CI, 2.18-3.29; P < .00001). There was an elevated incidence rate of in-season injuries in 2020 relative to 2014-2019 combined (IRR = 1.49; 95% CI, 0.98-2.19; P = .048). In 2013 to 2019, the most frequent month of injury was the first month of the preseason in August (119/334 tears; 35.6%), whereas in 2020, the most frequent month was September (13/41 tears, 31.7%). The proportion of tears in September 2020 was not different from the proportion of tears in August 2013 to 2019. CONCLUSION: There was an increased proportion of in-season ACL tears in the 2020 NFL season relative to 2014 to 2019; this is attributable to a frameshift in the consistent trend of injuries in the 1st month to return of competitive play, with 2020 being in the regular season in September as opposed to the preseason in August.