Background No gold standard exists for identifying successful outcomes 1 and 2 years after operative and non-operative management of anterior cruciate ligament (ACL) injury. This limits the ability of a researcher and clinicians to compare and contrast the results of interventions.

Purpose To establish a consensus based on expert consensus of measures that define successful outcomes 1 and 2 years after ACL injury or reconstruction.

Methods Members of international sports medicine associations, including the American Orthopaedic Society for Sports Medicine, the European Society for Sports Traumatology, Surgery, and Knee Arthroscopy and the American Physical Therapy Association, were sent a survey via email. Blinded responses were analysed for trends with frequency counts. A summed importance percentage (SIP) was calculated and 80% SIP operationally indicated consensus.

Results 1779 responses were obtained. Consensus was achieved for six measures in operative and non-operative management: the absence of giving way, patient return to sports, quadriceps and hamstrings’ strength greater than 90% of the uninvolved limb, the patient having not more than a mild knee joint effusion and using patient-reported outcomes (PRO). No single PRO achieved consensus, but threshold scores between 85 and 90 were established for PROs concerning patient performance.

Conclusions The consensus identified six measures important for successful outcome after ACL injury or reconstruction. These represent all levels of the International Classification of Functioning: effusion, giving way, muscle strength (body structure and function), PRO (activity and participation) and return to sport (participation), and should be included to allow for comparison between interventions.