Training in three phases The first phase of rehabilitation emphasizes knee range of motion for 6 weeks postoperatively: i. 2 weeks postoperatively . Exercise the quadriceps, isometric contraction, continuous passive motion (CPM) training is feasible . Start knee flexion and extension activities up to 90 degrees 3 days after surgery . Require straightening and hyperextension of the knee as much as possible and wear a brace in the continuous extension position. . The knee can be walked on crutches without weight-bearing on the affected limb. Second, 3~4 weeks after surgery . Continue functional exercise of quadriceps muscle and flexor strength exercise . Knee range of motion 0~120 degrees, restore hyperextension function. Wear a brace for walking on the ground without weight-bearing on the affected limb. Adjust the brace to 60 degrees. iii. 5-6 weeks after surgery . Continue functional exercise of quadriceps muscle and flexor muscle exercise . Knee range of motion reaches normal . Walk on the ground wearing a brace without weight-bearing on the affected limb. The second stage of rehabilitation is combined with strength training, 7 weeks~3 months postoperatively Stretch cord can be used to increase the strength training. At 7~8 weeks postoperatively, stair climbing and squatting are added. At 2~3 months, strengthen the weight-bearing training and strengthen the muscle strength of lower limbs Wear a support for normal walking or daily life training The third stage of rehabilitation is to increase special physical exercise. 3-12 months postoperatively Running is allowed at 3 months postoperatively. At 4-5 months postoperatively, rotation and twisting activities were started. 6~12 months after surgery . Non-confrontational sports activities are allowed . Avoid excessive rotational activities of the knee until muscle strength is restored.