Osteomalacia of the knee joint is a common and frequent disease in middle-aged and old-aged people. The naming of this disease has not yet been unified, and the main names are osteoarthritis, proliferative osteoarthritis, degenerative osteoarthritis, and bone spurs. The early pathological changes of knee osteoarthritis occur in the articular cartilage. First of all, the articular cartilage localized softening, erosion, and then the subchondral bone exposed, followed by the periosteum, joint capsule and muscle changes around the joint, so that the joint surface of the biological stress balance is out of balance, some parts of the stress to bear the fight is also the parts of the smaller, the formation of a vicious circle, the lesions continue to aggravate. Therefore, its clinical manifestations for the slow development of joint pain, pressure pain, stiffness, joint swelling, activity limitation and joint deformity. With age, the knee joint bones due to wear and tear over the years, the surrounding ligament laxity, resulting in joint instability, resulting in lesions caused by the corresponding parts of the osteophytes. This kind of hyperplasia is the phenomenon of human aging. after 40 years old, most people have osteophytes, only the occurrence of different parts and the degree of hyperplasia, some have symptoms, some asymptomatic. People can’t help but ask, why do older people have osteophytes? 1, traumatic factors: human joint cartilage every day to withstand a variety of activities caused by the mechanical force, people in middle age after the gradual decline in muscle function, resulting in joint instability, which can easily lead to joint injuries. Due to the injury, the knee joint weight-bearing force line changes, so that the knee joint surface effective weight-bearing area is reduced, the joint surface force is not uniform, the impact of the centralized part of the cartilage is prone to damage, and cause bone trabecular microfracture (subfracture), bone collapse, and then there is the phenomenon of osteosclerosis of the subchondral bone. 2. Changes in the composition of articular cartilage matrix and synovial fluid: Under normal circumstances, due to the presence of articular cartilage matrix and synovial fluid, the friction between the joints is very small, and will not cause wear and tear, unless overuse or injury. The cause of osteomalacia is abnormalities in synthetic cartilage components such as collagen (which is a tough, fibrous protein found in connective tissue) and mucin (a substance that produces cartilage elasticity). In addition, cartilage, although it grows vigorously, is very thin and its surface is susceptible to rupture. Periprosthetic bone growth around the knee joint is a repair phenomenon of joint injury, in which the body develops compensatory bone growth to increase the weight-bearing area of the joint and to decrease the stress it is subjected to. Bone overgrowth at the edge of the joint creates a mass that can be seen and felt (known as a bony outgrowth). Bone metaplasia causes uneven joint surface, interferes with normal joint function and causes pain. 3, autoimmune reaction: knee cartilage is damaged by mechanical factors, articular chondrocytes, mucopolysaccharide and collagen “hidden antigen” exposure, causing autoimmune reaction, resulting in secondary damage to the cartilage. The pathogenic factors of osteoarthritis of the knee in the elderly is not a single, the study found that osteoarthritis of the knee joint also has a certain relationship with the following factors: (1) age: aging is the strongest risk factor for the development of osteoarthritis. According to autopsy data, from the age of 20 years old, about 5% of the joints have degenerative changes, 40 years old, almost 90% of the weight-bearing joints have more or less osteophytic changes. Epidemiologic investigation found that: 16-30 years old, 31-40 years old, 41-50 years old, 51-60 years old, greater than 60 years old age group with knee pain, the positive rate of osteophytes were 10.6%, 14.8%, 29 .1%, 5 1.8%, 78.5%, respectively, and with the increase in age and the increase in the positive rate. (2) Sex: Before the age of 50, the incidence rate of women is 2 times higher than that of men, but after 50 years old, the incidence rate of both sexes is basically equal. (3) Occupation: Osteomalacia is related to occupation. Long-term repeated use of certain joints can cause an increase in the prevalence of these joints. For example, the spine and knee joints of miners, the knee and ankle joints of stevedores, due to long-term repeated use of a certain action, so that the joints are often subjected to wear and tear and caused by osteomalacia, squatting or kneeling for more than 30 minutes a day or climbing stairs more than 10 floors a day, there are obvious high incidence of osteomalacia in the knee joints. (4) Racial genetic factors: British people have the highest incidence while West Africans have the lowest, white people have a higher incidence than black people; women with osteoarthritis associated with Heber den nodules, their mothers and sisters suffering from this disease are 2~3 times of the general population. Moreover, the detection rate of HLA-A1 and HLA-B8 in patients with osteoarthritis is higher. (5) Physical factors: weight gain makes the degraded joints, which have already suffered from wear and tear, add heavy loads, and of course, they are more likely to be damaged, so osteoarthritis occurs more often in the weight-bearing parts of the hips, knees, heels, lumbar vertebrae and other parts of the body. In addition, due to joint pain, patients unconsciously limit the activities and make weight gain, the mutual influence and aggravate the joint lesions. Studies have found that people who are 20 pounds over the standard weight are 3.5 times more likely to develop osteoarthritis than those of normal weight. The site of occurrence is mostly the hip and knee joints. (6) Intraosseous venous stasis and intraosseous hypertension: the abnormal bone blood flow dynamics characterized by intraosseous venous stasis and the resultant intraosseous hypertension reduce the arterial and venous pressure difference, reduce the blood flow of nutritive blood vessels, and nutritional disorders may cause necrosis of bone trabeculae, and osteoclastic necrosis may be one of the reasons for inducing arthritis. Osteomalacia is one of the common diseases of middle-aged and elderly people, and the highest incidence of knee joints, into the old age, must be alert to the harm brought by osteomalacia of the knee joints, found that the symptoms should be early medical treatment, in order to early block the vicious circle of lesions, effectively slow down the progress of the disease, so that the elderly friends away from the joints pain, to enjoy a healthy life.