Epidemiology and Outcomes of Ankle Injuries in the National Football League

Abstract

Background: Traumatic ankle injuries are commonly complicated by persistent symptoms and the development of chronic ankle instability. Purpose: To describe the epidemiology of ankle injuries in the National Football League (NFL) and investigate the effects that ankle injuries have on performance metrics in the years after injury. Study Design: Descriptive epidemiologic study. Methods: Ankle injuries sustained by NFL players during the 2015-2016, 2016-2017, and 2017-2018 seasons were identified using the Pro Football Reference database. Cumulative incidence was calculated, and demographic identifiers were collected for each injury. The return-to-play (RTP) rate was also recorded. For each player who met inclusion for the performance analysis, power rating (PR) was calculated for the preinjury season (Y–1) and 2 postinjury seasons (Y+1 and Y+2) as follows: PR = ( offensive yards/10) + ( total touchdowns × 6) + ( combined tackles) + ( sacks × 2) + ( interceptions × 2). Mean PRs were calculated for each season as well as the percentage change and mean difference in PR between Y–1 and Y+1 (ΔPR1%, ΔPR1) and between Y–1 and Y+2 (ΔPR2%, ΔPR2). Subgroup analyses of PR were performed by player position, injury type, and years of experience. Results: Overall, 668 ankle injuries were identified, with an average cumulative incidence across the 3 seasons of 11.2% and RTP rate of 91%. Of those injuries, 159 met inclusion criteria for the PR analysis. The mean overall PR (96.95 in Y–1) declined 22% in Y+1 to 76.10 (–20.85 [95% CI, –13.82 to –27.89]; P < .001) and 27% in Y+2 to 70.93 (–26.02 [95% CI, –18.04 to –34.00]; P < .001). The mean PR per game played (6.70 in Y–1) decreased 14% in Y+1 to 5.75 (–0.95 [95% CI, –0.56 to –1.34]; P < .001) and 17% in Y+2 to 5.54 (–1.16 [95% CI, –0.63 to –1.62]; P < .001). Conclusion: It was found that ankle injuries hampered the performance of NFL players, even multiple years after the injury occurred, despite a relatively high RTP rate. There was a decrease in total games played after ankle injuries as well as a decreased performance output per game played.