The knee, the largest and most complex joint in the human body, is a hinge joint, and it is one of the few joints in our body that can only move in one direction. It is also the largest weight-bearing joint in the human body, with a normal knee joint bearing an average of 35 kilograms. The more weight a person bears, the greater the chance that the cartilage in the joint will wear out, and the tendons will be easily injured, resulting in faster degradation of the knee joint. According to expert research statistics, the knee joint load times are as follows: 1, lying down, the weight of the knee joint is almost 0. 2, standing up and walking, the weight of the knee joint is about 1 to 2 times the weight. 3, up and down the slope or up and down the stairs, the weight of the knee joint is about 1 to 2 times the weight. 3, when going up and down the slope or up and down the stairs, the weight of the knee joint is about 3~4 times of the body weight . 4. When running, the weight of the knee joints is about 4 times of the body weight. 5. When playing soccer, the weight of the knee joints is about 6 times the weight of the body. 6, squatting and kneeling, the weight of the knee joint is about 8 times of the body weight. The human knee joint quality has 15 years of the best state Before 15 years old: the knee joint is in the development stage, puberty growing pains occur mostly near the knee joint. From 15 to 30 years old: the knee joint is in a “perfect state” and works tirelessly. As long as it doesn’t damage the knee joint tissues, you basically can’t feel its existence. 30~40 years old: The patellar cartilage has early mild wear and tear, and there will be a fragile period of short-term knee pain that lasts for a few weeks to a few months, and some people may not even be aware of it. The patellar cartilage is a 3 to 5 millimeter thick layer of transparent cartilage in the human knee joint that cushions the knee from the impact of movement. But because the patellar cartilage has no nerve distribution, so in the whole layer before the wear and tear will only be in the fragile period of pulling a “warning signal”, in this period to avoid strenuous exercise. From this time onwards, you can no longer use your knee as you wish. 40~50 years old: After walking long distances, the inner side of the knee joint tends to become sore, which can be relieved by gently rubbing it with your hands. In the knee joint, the meniscus serves to cushion shock and maintain stability. Since 60% of the body weight is supported by the inner side of the knee, degeneration of the inner meniscus occurs earlier. And because there are nerves in the meniscus, one can feel the soreness during the degeneration process. The arrival of this phenomenon reminds people that it is time to start taking care of their joints. Above 50 years old: knee joint will feel obvious pain, this is because the patellar cartilage “service life” has come to the cartilage whole layer wear, arthritis has arisen. This time should be used sparingly joints, reduce strenuous exercise, especially up and down the stairs and climbing, if necessary, you can use crutches to reduce the pressure on the knee joints. Reasons for knee pain in the middle-aged and elderly After middle age, the knee joint tendons, ligaments began to degenerative changes in the joint cavity of the synovial fluid secretion is reduced, long-term friction of the joint bone surface to form bone abrasion, joints around the tissues due to inflammation and other reasons are prone to fibrous adhesions, so the elderly often feel stiff knee joints, activities will be issued when the “clacking Therefore, the elderly often feel stiffness in the knee joints, and when they move, they will make “clicking” sound or friction sound, and when they are cold or over-active, it will induce pain, swelling, and fluid accumulation in the joint cavity, and in serious cases, it will also make the joints of the elderly deformed and form disability. Specifically, the causes of knee pain in middle-aged and elderly people are as follows: 1, chronic synovitis: manifested as chronic pain and swelling in the knee joint. The examination can see synovial effusion and synovial hypertrophy. 2.Patellar deviation: the knee joint is sore and weak after activity, it is better after rest, and it is painful when half squatting. 3.Knee joint free body: the patient’s leg is weak or there is a sense of joint jamming, infrapatellar friction sound. 4.Pre-patellar bursitis: there is a history of trauma, which causes pre-patellar pain and localized induration on examination. 5.Osteoarthropathy: joint pain is obvious when standing up or going up and down stairs after sitting or squatting for a long time, and relieved after resting. 6.Pseudogout: male patients are more, preferably in the knee joint. It is characterized by swelling and pain, high skin temperature and functional limitation. x-ray film shows calcification of meniscus and articular cartilage surface. 7, femoral head necrosis: hip joint lesions with knee pain symptoms. In principle, all the above situations of knee pain, should be timely to the hospital to find a specialist to confirm the diagnosis, treatment. Daily health care for knee pain: 1, don’t walk for too long, when the knee feels uncomfortable, you should rest immediately. 2, do not do large exercise, such as running, high jump, long jump. 3, avoid half squatting, full squatting or kneeling position. Such as squatting horse stance. 4, do not do half-flexion rotary action of the knee to prevent half-plate injury. 5, maintain the ideal weight to reduce the burden on the knee joint. 6, pay attention to the warmth of the knee joint, can wear long pants, knee pads to protect the knee. 7, Less carry heavy objects, less wear high heels. 8, avoid trauma and excessive labor. 9, the choice of shoes is very important. A pair of well-fitting shoes can not only make you walk comfortably, but also reduce the impact and pressure on the knee joints during exercise. (1) The instep part of the foot can be closely combined with the shoes, and the width and length are suitable to maintain the arc of the arch correctly. (2) The weight of the shoes should be light, and the soles should not be too soft and should be a little thick. (3) The heel of the shoe can be about 2-3 centimeters high, and if the sole is too flat, it is easy to get tired when walking. (4) Shoes with non-slip patterns on the soles. Should I exercise when my knee is injured? In the case that the knee joint has been injured, unreasonable exercise will lead to secondary damage to the knee, and over time, the meniscus of the knee joint will lose its protective and cushioning effects due to wear and tear, and the heavier ones may be inconvenienced by walking. The knee joint is a hinge joint and can only move back and forth, not side to side. When the knee joint is injured, the first thing to do is to pay attention to the protection, if allowed, you can carry out simple back and forth movement, to promote the blood circulation of the knee joint, but it is not suitable for strong activities, the movement is not enough to cause stiffness of the knee joint, excessive movement will accelerate the wear and tear of the joint, but the movement is still to the extent that the joint does not feel the pain.