Typically, athletes are cleared 4 to 6 months after ACL surgery and expected to immediately return to pre-injury level. This conventional 4 to 6 month time frame does not take into account an athlete's individual capabilities.
Research has demonstrated that within the first twelve months after ACL surgery, the risk of a second ACL injury significantly increases. Not only is the surgically repaired knee at greater risk of re-injury, but the opposite knee is also at an increased risk of injury, if return to sport is allowed too soon. It is discouraged to use time since surgery as the sole determinant for returning to sport. To decrease the risk of re-injury, it is recommended that specific testing be performed to determine whether each athlete has both the physical and psychological abilities to successfully return to sport.
A study published in the British Journal of Sports Medicine reported that athletes who did not meet six discharge criteria before returning to sport were at a four times greater risk of re-injury. These discharge criteria included strength, power, agility testing, and on-field sports specific rehabilitation.
Additionally, there is growing evidence that psychological factors, including fear of re-injury, confidence in the surgically repaired knee, motivation, and optimism, play a significant role in successful return to sports participation.
As physical therapists and athletic trainers, it is our job to ensure athletes are sufficiently prepared to return to sport. This is accomplished by providing athletes with questionnaires to assess their confidence and fear of re-injury, followed by a thorough battery of physical tests to ensure the surgically repaired knee is capable of handling the stresses it will encounter in sport.
There is still much work to be done in decreasing re-injury rates after ACL surgery. Preventing an ACL re-injury is impossible but recent research shows the risk can be reduced with proper rehabilitation and testing. We recommend a combination of questionnaire and physical testing prior to return to sport, as time since surgery is only one of many important factors in complete recovery.