1, chronic strain: long-term poor posture, weight-bearing force, excessive weight, resulting in soft tissue damage to the knee joint. 2, obesity: the increase in weight and the onset of osteoarthritis of the knee is proportional. Obesity is also an aggravating factor. Weight loss in obese people can reduce the onset of osteoarthritis of the knee. 3, bone density: When the subchondral bone trabeculae become thin and stiff, their tolerance to pressure is reduced, so the chances of osteoarthritis in osteoporotic patients will increase. 4, trauma and force bearing: frequent knee injuries, such as fractures, cartilage, ligament damage. Abnormal state of the joint, such as in the post-patellar resection link in an unstable state, when the joint withstand muscle force imbalance and coupled with local pressure, there will be degenerative changes in the cartilage. Normal joints and activities or even after strenuous exercise is not osteoarthritis. 5, genetic factors: joint involvement varies from race to race, such as hip, carpometacarpal joint osteoarthritis in Caucasians, but people of color and the country is rare, gender also has an impact, the disease is more common in women. Data show that the incidence of osteoarthritis in mothers and sisters of women with Heberden’s nodes is 2-3 times higher than in family members without the disease.