Background Prevention strategies for ACL injuries in Olympic sports are mandatory and the collection of data about risk factors and injury characteristics have highest priority.

Objective What are the main risk and influencing factors on ACL injuries and safe return to play in different sports, beginning with worl's number one sport football?

Design A prospective analysis of ACL injuries in German amateur and professional football.

Setting ACL injury registration over two football seasons and investigation of ACL injured player by 2 questionnaire after injury and after one year.

Patients Players of German football divisions were investigated, including all divisions, both gender and all age levels.

Interventions Beside typical influencing and risk factors for ACL injuries, circumstances for a return to play decision were investigated.

Main Outcome Measurements Investigated variables are anthropometric data, football exposure data, training and warm up data, regeneration data and return to play decision-making.

Results 512 ACL injuries in football were registered in the first season with 71.1% non-contact injuries, 85.5% match injuries, younger female players and 93.5% surgical treatment rate. 68% of ACL injuries occurred in the preseason period, 60% of 1st division players were internationals and the first professional division revealed a higher ACL rate than the 2nd and 3rd division. Balancing exercises (<40%) or trunk stability exercises (<20%) were rare. Small pre-injuries were seen in 30% of all players directly before ACL injury. Over 50% had directly before the ACL injury changes of the training program or football level. Changing of football shoes before ACL injury was seen in 33.3%. A mean of 9.2 months for return to competition was seen in the male professional football players, which was earlier than in amateurs.

Conclusions To improve injury prevention strategies for ACL injuries, a detailed knowledge about injury characteristics is necessary in all sports.