Multiple Ankle Injuries are Associated with an Increased Risk of Subsequent Concussion in National Football League Players

Abstract

Category: Sports; Ankle Introduction/Purpose: Ankle injuries are among the most common musculoskeletal injuries in National Football League (NFL) players. Concussions are also concerningly frequent, especially given increasing post-mortem observations of chronic traumatic encephalopathy (CTE) in former NFL players. There is a gap in the literature regarding musculoskeletal risk factors for concussion, which is an avenue that must be explored to promote player safety. The purpose of this study is to observe if ankle injuries, especially multiple ankle injuries, are associated with an increased risk of subsequent concussion in NFL players. Methods: The public online database ProFootballReference.com was utilized to identify ankle injuries and concussions in NFL players, as well as demographic variables such as BMI and age. Multivariable logistic regression for subsequent concussion and ankle injury was performed, adjusting for BMI and player position. For descriptive statistics, unpaired T-tests with unequal variance were performed for continuous variables, including BMI and age. Chi-squared testing was performed for categorical variables, including player position, and whether the position was offensive (quarterback, running back, tight end, wide receiver, offensive line), defensive (defensive back, defensive line, linebacker), or on special teams (kicker, punter, long snapper). Results: 5,538 NFL players from the 2009-2010 to 2019-2020 seasons were included in the study. The mean BMI and age of the cohort was 31.06 (SD 4.55) and 24.41 (SD 3.63), respectively. Of these players, 941 had an ankle injury, 633 had a concussion, and 240 had both an ankle injury and a subsequent concussion. The adjusted odds ratio (aOR) for concussion following a single ankle injury was 0.90 (95% CI 0.72 – 1.14, p = 0.387), however, the aOR for concussion following multiple ankle injuries was 2.88 (95% CI 1.28 – 6.74, p = 0.015). The kicker position was determined to have the lowest risk for concussion following ankle injury, and the positions with comparatively greater risk are outlined in Table 1. Conclusion: Multiple ankle injuries were associated with an increased risk of a subsequent concussion by 188% after adjusting for BMI, player position, and offense/defense/special teams designation. Special teams as a group and by position (kicker, long snapper, punter) had the lowest risk of concussion following ankle injury, likely owing to the lower-impact nature of these positions. These findings can inform injury prevention practices in the National Football League.