Predictive factors for 12-month outcome after anterior cruciate ligament reconstruction.

There is a lack of knowledge regarding predictive factors for a successful clinical outcome after an anterior cruciate ligament (ACL) reconstruction. The aim was to investigate pre-operative factors that may predict good outcomes as measured with the subscales Function in sports and recreation and Quality of life in Knee injury Osteoarthrithis Outcome Score (QOL-KOOS), one-leg hop test and Tegner Activity Scale 12 months after ACL reconstruction. Sixty-four patients, operated with either patellar or hamstring tendon graft, were included. Demographics, range of motion, anterior knee laxity, pivot shift, muscle-torques, anterior knee pain (AKP) and knee function were registered pre-operatively and used in a multiple regression model. Results show less degree of AKP and low influence on knee function to be the most important predictors for good outcome in Sport/Rec-KOOS (explained 31% of variances). Less AKP was in addition the most important predictor for QOL-KOOS (14%). Patellar-tendon graft, in favor of hamstring tendon graft, explained 8% of the improvement in the Tegner Activity Scale. In conclusion, a low degree of AKP was found to be the most important predictor for good clinical outcome 12 months after ACL reconstruction. Future studies, including psychological parameters, should use analyses that have the potential to control for independency between variables.