Summary

BACKGROUND: Determining readiness to return to sport after anterior cruciate ligament (ACL) reconstruction is challenging. OBJECTIVES: To develop models to predict initial (directly after rehabilitation) and sustainable (one year after rehabilitation) return to sport and performance in individuals after ACL reconstruction. METHODS: We conducted a multicentre, prospective cohort study and included 208 participants. Potential predictors - demographics, pain, effusion, knee extension, muscle strength tests, jump tasks and three sport-specific questionnaires - were measured at the end of rehabilitation and 12 months post discharge from rehabilitation. Four prediction models were developed using backward logistic regression. All models were internally validated by bootstrapping. RESULTS: All 4 models shared 3 predictors: the participant's goal to return to their pre-injury level of sport, the participant's psychological readiness and ACL injury on the non-dominant leg. Another predictor for initial return to sport was no knee valgus, and, for sustainable return to sport, the single-leg side hop. Bootstrapping shrinkage factor was between 0.91 and 0.95, therefore the models' properties were similar before and after internal validation. The areas under the curve of the models ranged from 0.74 to 0.86. Nagelkerke's R2 varied from 0.23 to 0.43 and the Hosmer-Lemeshow test results varied from 2.7 (p = 0.95) to 8.2 (p = 0.41). CONCLUSION: Initial and sustainable return to sport and performance after anterior cruciate ligament reconstruction rehabilitation can be easily predicted by the sport goal formulated by the individual, the individual's psychological readiness, and whether the affected leg is the dominant or non-dominant leg.