PT - JOURNAL ARTICLE AU - M Waldén AU - M Hägglund AU - J Ekstrand TI - High risk of new knee injury in elite footballers with previous anterior cruciate ligament injury AID - 10.1136/bjsm.2005.021055 DP - 2006 Feb 01 TA - British Journal of Sports Medicine PG - 158--162 VI - 40 IP - 2 4099 - http://bjsm.bmj.com/content/40/2/158.short 4100 - http://bjsm.bmj.com/content/40/2/158.full SO - Br J Sports Med2006 Feb 01; 40 AB - Background: Anterior cruciate ligament (ACL) injury is a severe event for a footballer, but it is unclear if the knee injury rate is higher on returning to football after ACL injury. Objective: To study the risk of knee injury in elite footballers with a history of ACL injury compared with those without. Method: The Swedish male professional league (310 players) was studied during 2001. Players with a history of ACL injury at the study start were identified. Exposure to football and all time loss injuries during the season were recorded prospectively. Results: Twenty four players (8%) had a history of 28 ACL injuries in 27 knees (one rerupture). These players had a higher incidence of new knee injury of any type than the players without ACL injury (mean (SD) 4.2 (3.7) v 1.0 (0.7) injuries per 1000 hours, p  =  0.02). The risk of suffering a knee overuse injury was significantly higher regardless of whether the player (relative risk 4.8, 95% confidence interval 2.0 to 11.2) or the knee (relative risk 7.9, 95% confidence interval 3.4 to 18.5) was used as the unit of analysis. No interactive effects of age or any other anthropometric data were seen. Conclusion: The risk of new knee injury, especially overuse injury, was significantly increased on return to elite football after ACL injury regardless of whether the player or the knee was used as the unit of analysis.