After patella surgery, reasonable functional exercise under the guidance of the doctor, generally in about 1 month can be bent 90 degrees, but the specific time there are individual differences. After patellar fracture surgery, rehabilitation training is required under the guidance of the physician to ensure that the knee joint function returns to normal after surgery. About 1 month after the fracture surgery, the broken end starts to heal, and the fiber connection appears, at this time the fracture place is gradually restored to be stable, and the rehabilitation training can be carried out gradually, and it is possible to bend up to 90 degrees under no weight bearing condition. However, for patients with more serious conditions, slower postoperative recovery, or patients who do not have timely functional training, the time required for knee bending will be longer. In addition, after patellofemoral surgery, knee joint activity training should be carried out in strict compliance with the doctor’s instructions, to avoid excessive flexion, injury to the fracture end, resulting in delayed healing of the fracture or breakage of the internal fixation and so on. If the knee is braked for a long period of time without training, it may lead to soft tissue adhesion around the knee joint, stiffness of the joint and limited movement.