When can I start rehabilitation exercises after surgery? Post-operative rehabilitation should be planned by the physician based on the patient’s primary condition, surgical incision access, surgical history, prosthesis requirements, local knee condition, systemic status and complications, patient’s mental and psychological status, age, and financial ability. The implementation of the rehabilitation plan is carried out by the patient himself, his family and the medical staff. Patients with post-stable knee surface prosthesis replacements keep the affected limb in the straight position for 2-3 days after surgery. When the drainage tube is removed and the prosthesis is in good position by radiographs, rehabilitation exercises can be started using a continuous passive mobilizer (CPM) to restore knee mobility; followed by muscle strength recovery training. How to control the amount of exercise for post-operative rehabilitation exercises? It is not the quantity but the quality of the daily flexion and extension activities during rehabilitation exercise. Try to straighten and flex the knee joint to a certain degree so that there is progress every day, and if there are too many activities, the number of flexion and extension activities must be reduced when joint swelling occurs.