Osteoarthritis is a common and frequent disease among middle-aged and elderly people. Its onset can be caused by damage to the articular cartilage due to excessive wear and tear of the knee joint, or by a lack of exercise over the years, resulting in malnutrition of the articular cartilage, which eventually leads to easy degeneration and damage to the cartilage. In younger athletes, the knee joint can also develop lesions similar to osteoarthritis in middle-aged and older adults due to long-term heavy and high-intensity training, as well as other injuries to the knee joint. However, the cause of osteoarthritis in athletes is generally due to excessive wear and tear. The main manifestations of osteoarthritis are knee pain, swelling, or weakness, with pain and weakness more pronounced in squatting or walking up and down stairs. The swelling is mostly related to how much activity is involved, and swelling will increase with more activity, and will decrease or even disappear with good rest. Many patients complain of very pronounced weakness in the knee joint when going up or down stairs, but feel good when walking on a flat road. In severe cases of osteoarthritis, the knee joint may become deformed, resembling an “O” or “X” shaped leg, and this deformation may become more severe as the disease worsens. Many people with mild or even moderate osteoarthritis of the knee can be relieved by non-surgical treatment, such as oral medication, physical therapy, topical Chinese medicine, and rehabilitation exercises. If non-surgical treatment is ineffective, surgery will be performed. There are various methods of surgical treatment. The practice of incision for joint debridement is now obsolete and has been replaced by minimally invasive arthroscopic surgery. Some patients with severe osteoarthritis of the knee must have an artificial knee joint replacement to receive satisfactory results.