The old rebound after knee surgery exercise may be related to physiological factors, peripheral tissue damage, scar tissue hyperplasia, the treatment mainly includes adherence to rehabilitation exercises, medication, physiotherapy and so on. 1. Physiological factors: the muscles and ligaments around the knee joint are soft tissues with elasticity and adhesion, which have a tendency to retract after being pulled and extended, and the tissues retract when resting after rehabilitation exercise, and the knee joint may flex to a smaller extent on the next day, but it can be improved by adhering to the rehabilitation exercise in general. 2. Peripheral tissue damage: damage to peripheral tissues during surgery or tissue damage caused by non-standard rehabilitation exercises, resulting in tissue adhesion, affecting nerve function, rebound can occur. Nutritional nerve drugs (e.g. methylcobalamin), non-steroidal anti-inflammatory drugs (e.g. celecoxib), etc. can be taken, and magnetic heat therapy can also be used for improvement. 3. Scar tissue hyperplasia: after knee surgery in the early 3 to 4 weeks, knee rehabilitation exercise to increase the degree of bending significantly, followed by soft tissue fibrous scar formation, which can also lead to rebound, but by adhering to the exercise can gradually be pulled away. Post-operative knee exercise will rebound, it is recommended to adhere to the rehabilitation exercise under the guidance of the doctor, in order to promote recovery. In addition, the above drugs should also be used under the guidance of a doctor.