Post-operative rehabilitation after arthroscopic meniscus injury: postoperative compression bandage of cotton leg of the affected limb for 3 days; if necessary, use external fixation support to immobilize the affected knee for 4-6 weeks (in the operation, we saw severe meniscus injuries, such as barrel shank-like tear). Week 1-2: fix the affected knee in the straight position; after the postoperative anesthesia effect, instruct the patients to practice muscle strength exercises, such as ankle pump, quadriceps tendon isometric exercises, straight leg raising exercises, etc.; after 1 week of postoperative period when the inflammation gradually subsides, temporarily remove the brace, instruct the patients to passively practice knee flexion activities in bed, gradually increase the angle of flexion, in order to the degree that the affected knee does not have obvious pain; during this period the patients have to wear the brace when going down to the ground, and try to hold the knee in a straight position, and then use an external fixation brace to fixate the affected knee. During this period, the patient must wear a brace when going down to the floor, and the patient should be immobilized in the straight position and walk with crutches. When walking without pain for 2 weeks after surgery, the crutches can be taken off. The 3rd-4th week: instruct the patient to continue the muscle strength exercise; instruct the patient to actively practice knee flexion activities in bed, gradually increase the exercise angle, to the extent that the affected knee does not have obvious pain; if necessary, the patient must wear a brace on the ground and walk with crutches. 3 weeks after the operation, strengthen the active extension and flexion exercises, and start squatting exercises. 4 weeks after the operation, start to practice up and down steps.