An athlete's intention to return to sport following anterior cruciate ligament (ACL) injury is a major indication for surgical intervention.The purpose of this review was to determine postoperative return-to-sport outcomes after ACL reconstruction surgery.Meta-analysis and systematic reviewElectronic databases including Medline, Embase, SPORTDiscus and CINAHL were searched from the earliest possible entry to April 2010. Studies were included that reported the number of patients returning to sports participation following ACL reconstruction surgery. The results were presented using the World Health Organization's International Classification of Functioning, Disability and Health as a framework and combined using proportion meta-analyses.Forty-eight studies evaluating 5770 participants at a mean follow-up of 41.5 months were included for review. Overall, 82% of participants had returned to some kind of sports participation, 63% had returned to their preinjury level of participation, and 44% had returned to competitive sport at final follow-up. Approximately 90% of participants achieved normal or nearly normal knee function when assessed postoperatively using impairment-based outcomes such as laxity and strength, and 85% when using activity-based outcomes such as the International Knee Documentation Committee knee evaluation form. Fear of reinjury was the most common reason cited for a postoperative reduction in or cessation of sports participation.The relatively low rate of return to competitive sport despite the high rates of successful outcome in terms of knee impairment-based function suggests that other factors such as psychological factors may be contributing to return-to-sport outcomes.