Osteoarthritis, also known as osteoarthrosis, degenerative arthritis, etc., is the number one chronic disease causing disability in adults, causing great pain to patients and enormous pressure on society. The incidence of osteoarthritis in China is very high, accounting for about 10% of the population, and the incidence is as high as 60-70% in people over 50 years old. 2000-2010 was officially designated as the Bone and Joint Decade by the United Nations Secretary-General Annan in November 1999, and October 12 of each year was designated as the International Arthritis Day. The knee is one of the most common joints affected by osteoarthritis, and is often involved bilaterally. The most common clinical symptom is joint pain, which starts as intermittent episodes of mild to moderate severity and can become persistent or even tearing or pins and needles pain, especially on cloudy days when it is raining because of localized cold in the joint. Another major symptom of osteoarthritis is the impairment of joint movement. The stiffness and tightness of the joints after waking up in the morning and the lack of movement are called morning stiffness, and the stiffness is relieved only after a period of activity. In severe cases, joint subluxation and deformity can be seen. The articular cartilage plays an important role in the movement of the joint, cushioning the pressure, like a spring cushion between the railroad track and the sleeper, protecting the bones under the cartilage from damage. In addition, articular cartilage has a lubricating effect, minimizing friction and wear during movement. It is generally believed that degenerative changes in articular cartilage begin after the age of 25. As we reach middle age, all organs of the body age, and articular cartilage is no exception. At this time, the metabolism of cartilage cells becomes abnormal, resulting in the loss of proteoglycans in cartilage, which causes a decrease in the elasticity of articular cartilage and localized softening. Slowly the articular cartilage becomes locally eroded and worn out, causing damage and loss of cartilage structure, resulting in mutual wear and tear between subchondral bone and bone, accompanied by osteophytes in the process. Simultaneous inflammation of the synovial membrane produces inflammatory mediators that accelerate the dissolution of articular cartilage, creating a vicious cycle. What can cause osteoarthritis?1. Age: aging is the most risk factor for the occurrence of osteoarthritis, the incidence increases with age, about 60% of people over 50 years of age suffer from this disease, especially in older women.2. Joint injury: is a common cause of osteoarthritis of the knee joint, which can increase the local load and wear of the articular cartilage surface, cruciate ligament and meniscus injury, with the knee joint Osteoarthritis is particularly close. 3, obesity: excessive weight increases the load on the knee joint, leading to changes in posture and walking gait, and the load on the lower limbs is often concentrated on the medial cartilage of the knee joint, increasing the wear and tear on the cartilage surface. 4, overuse or excessive exercise: the prevalence of osteoarthritis is closely related to occupation, and long-term, repeated use of the knee joint and beyond a certain limit can cause osteoarthritis. 5. Estrogen: The prevalence of osteoarthritis increases significantly after menopause and is related to ovariectomy, indicating that the occurrence of osteoarthritis in women is related to estrogen levels in the body. After understanding these causes, take some measures to prevent the occurrence of osteoarthritis of the knee. These include moderate physical exercise, not being overweight, avoiding joint damage, taking glucosamine drugs, and for women, taking small doses of estrogen to slow down the degeneration of joint cartilage. Once osteoarthritis occurs in the knee, early patients can take non-steroidal anti-inflammatory and pain-relieving drugs, supplemented by physical therapy to relieve symptoms and functional exercises for the quadriceps to stabilize the knee joint. If the treatment is not effective and the swelling of the knee joint does not subside repeatedly, arthroscopy and debridement are feasible in selected cases. If biomechanical changes in the knee joint occur, with internal or external knee deformities affecting the lower limb load transmission, osteotomy is required. For advanced osteoarthritis of the knee, total knee arthroplasty is a wise choice. With the current medical conditions and the skill level of the doctors in China, the patient can get a satisfactory functional recovery of the knee joint after surgery.