At the early stage of osteoarthritis, cartilage lesions can be repaired surgically, such as by microfracture surgery or regenerative medicine based techniques. Post-surgical rehabilitation is critical for the quality of new tissue and patient outcome, but the rehab protocol remains a heavily debated topic. Partial weight bearing on the operated knee are started from 0 to 8 weeks after surgery and could last for another 1-8 weeks before full weight bearing and return to sports. Such a wide divergence in practice is mainly due to the lack of scientific evidence to guide the design of rehabilitation progressions. In this project, we build a novel research strategy by which the microfracture procedure and post-surgical rehabilitation can be simulated on cartilage-bone allografts. Knee loading profiles during partial weight bearing and joint motion are extracted from physical therapy studies and input into a 3D FEM knee joint model. Outcome from the FEM simulation are employed to guide the mechanical loading on cartilage-bone explants during culture. We are now testing the safety and feasibility of a criterion based rehabilitation progression in human subjects after microfracture surgery of the femoral condyle.