OBJECTIVE: In this study a numerical model of a skier was developed to investigate the effect of different rehabilitation strategies after anterior cruciate ligament (ACL) rupture. METHODS: A computer model using a combined finite-element and multibody approach was established. The model includes a detailed representation of the knee structures, as well as all major leg muscles. Using this model, different strategies after ACL rupture were analyzed. RESULTS: The benefit of muscle training to compensate for a loss of the ACL was shown. The results indicate that an increase of 10% of the physiological cross-sectional area has a positive effect without subjecting other knee structures to critical loads. Simulating the use of a hamstring graft indicated increasing knee loads. A patellar-tendon graft resulted in an increase of the stress on the lateral collateral ligament. CONCLUSION: Muscle training of both extensors and flexors is beneficial in medical rehabilitation of ACL-deficient and ACL-reconstructed knees.