Single Season Re-Injury Risk after Concussion and Lower Extremity Injury among Male, Collision Sport, High School Athletes

Abstract Objectives Research suggests that a recent concussion increases subsequent lower extremity injury risk; however, data in high school athletes is limited. This study evaluates the association between concussion and subsequent injury risk among male, collision sport, high school athletes over a single season. Design Retrospective cohort study Methods Data were obtained from 2005/06-2014/15 in the High School Reporting Information Online database. A two stage, multi-method matching process was used to identify athletes who suffered multiple injuries over a single athletic season. Demographics and injury characteristics were compared with Chi square and Student’s t-tests. Multiple Cox Proportional Hazards regression analysis was used to test whether index injury type was associated with hazard of subsequent injury following return to play from index injury. Results Overall 1364 HS athletes sustained 2 injuries over a single athletic season (subsequent injury within 45 days of the index injury). Index injuries included 686 (50.2%) lower extremity injuries, 417 (30.6%) upper extremity injuries, and 261 (19.1%) concussions. Hazard of subsequent concussion was increased in the index concussion group relative to the index lower extremity injury group [hazard ratio (HR): 1.60, 95% CI: 1.15-2.23, p = 0.0052]. Hazard of a subsequent lower extremity injury was not significantly different for the index lower extremity injury group relative to the index concussion group [HR: 1.27, 95% CI: 0.98-1.65, p = 0.0728]. Conclusions History of recent concussion or recent lower extremity injury are both risk factors for subsequent lower extremity injury in male, collision sport, high school athletes.