Arthroscopy has gradually replaced some surgeries that used to require incision because of its small trauma and positive results. Arthroscopy does not expose the joint cavity, and the surgery is performed in liquid environment, which causes little disturbance to the articular cartilage and greatly shortens the post-operative recovery time; arthroscopy not only shows the lesion clearly, but also can penetrate into some hidden parts, and even some extra-articular diseases can be applied to this technology, which provides a good means for sports trauma diagnosis and treatment. 1, meniscus injury People in a fall, body twisting, or external impact can damage the meniscus. After meniscus injury, patients often feel pain in the knee joint when walking, and often have a feeling of “stopping” the joint. They may also experience thinner thighs and pain when walking up and down stairs or squatting. The meniscus is the half-moon shaped cartilage in the knee joint between the thigh and calf bones, which protects the joint surface by cushioning the joint pressure. Meniscal injuries generally do not heal on their own and require arthroscopic surgery to remove or repair the damaged portion. 2, rupture of the anterior cruciate ligament of the knee joint people in a fall, body twisting, or external impact can also damage the ligament, ligament damage after the knee joint instability, patients have difficulty running, can not jump, the joint hit soft, can also appear thigh thinning, up and down the stairs or squatting pain, etc.. The anterior cruciate ligament cannot heal on its own after rupture, and this ligament should be reconstructed under arthroscopic surgery. 3, knee patellar disease Abnormal shape or position of the patella due to genetics, trauma, muscle atrophy and other reasons. The patient has knee pain when walking up and down stairs, squatting or standing up, but no discomfort when walking or jumping on a flat surface (sometimes called chondromalacia patellae). The patella, commonly known as the “kneecap,” is located in front of the knee joint. It supports the body’s activities such as walking up and down stairs, squatting and standing up. This condition often requires arthroscopic surgery to correct the position of the patella. 4. Intra-articular free bodies in the knee are often formed in the joint as a result of trauma or the breakage of an intra-articular bone spur and can wander. When the fragment travels to the middle of the joint, it causes joint pain and locking, and it gradually recovers after slowly moving out of the joint space. The free body needs to be removed arthroscopically. 5. Fibrous band hyperplasia in the knee joint The patient has pain or leg weakness when going up and down stairs, squatting or standing up, but walking or running on a flat road is not limited. This is due to the fact that the edge between the kneecap and the thigh bone often has a thin film of fibrous tissue left over from the congenital process, and trauma or inflammation can cause it to thicken and enlarge, and extend into the gap between the kneecap and thigh bone and cause symptoms. The band needs to be removed arthroscopically. 6. Mild to moderate arthritis of the knee Joint degeneration in old age, joint osteophytes, joint spurs, post-traumatic arthritis, rheumatoid arthritis and other diseases cause mild to moderate damage to the cartilage on the surface of the knee joint. Patients experience joint pain when walking, restricted movement, joint extension, or joint deformities such as O-leg, X-leg, or K-leg. Patients who are temporarily unable or unwilling to undergo joint replacement surgery may have their pain temporarily relieved by arthroscopic surgery to remove bone spurs and recondition the joint surface.