In recent years, there have been an increasing number of patients with knee pain, and many people have experienced knee pain, but the causes of knee pain are not well understood. The knee joint is the larger and more complex flexor joint in the body, which is subject to high stress and has a stable yet flexible structure. There are many causes of knee pain, but not all causes of knee pain are caused by lesions of the knee joint. There are also knee pains that are caused by lumbar and hip lesions that cause radiating pain in the knee joint. 1. Knee pain caused by knee injury 1. Fat pad strain The fat pad fills the gap in the front of the knee joint, which has the effect of strengthening the joint stability and reducing friction. The cause of fat pad strain may be due to trauma or long-term friction that causes fat pad congestion, hypertrophy and inflammation, and adhesion with the patellar ligament, thus limiting the movement of the knee joint. This injury occurs in people over 30 years of age who walk, hike or squat frequently. Patients may feel pain in the knee joint, which is worse when fully extended, but there is no restriction of joint movement. The symptoms are obvious after exertion. 2, meniscal injury Meniscal injury is a common injury in athletes. When the lower limb is weighted, the foot is fixed, and the knee is slightly flexed, a sudden excessive internal rotation of the knee extension or external rotation of the knee extension (for example, in volleyball, the player suddenly turns and fishes to save the ball while defending) may cause a meniscal tear. A meniscal injury can be characterized by a distinct tearing sensation in the knee, followed by joint pain, limited motion, and a walking limp. The joint exhibits swelling and slipping sensations and pops when the joint is moved. 3. Traumatic synovitis of the knee joint The synovial membrane of the knee is one of the main structures that make up the knee joint. Synovial cells secrete synovial fluid, which keeps the cartilage surface of the joint slippery and increases the range of motion of the joint. Injury to the synovial membrane due to trauma or overexertion can produce a large amount of fluid, which increases the pressure in the joint and, if not eliminated in time, can easily cause joint adhesions and affect normal activities. Patients will feel pain, swelling and pressure in the knee joint, and the synovial membrane has a frictional and astringent sound. The most obvious feature of the pain is that when the knee joint is actively and extremely extended, especially when there is a certain resistance to do the knee extension movement, the pain in the lower part of the patella will be increased, and the pain is also significantly increased when it is passively and extremely flexed. 4, osteoarthritis of the knee joint This condition is mostly seen in middle-aged and elderly people, mostly women. Overweight loading is the main cause of the disease. The knee joint will be swollen and painful, and sometimes there will be friction sounds when moving the joint. The knee may have an inversion deformity and be accompanied by medial pain. 5. Knee ligament injury The stability of the knee joint is relatively poor when it is slightly flexed. If a sudden external force causes valgus or inversion at this time, it may cause medial or lateral collateral ligament injury. Medial collateral ligament injuries account for the majority of clinical cases. In this injury, for example, the patient will have a clear history of trauma, pain and pressure on the medial side of the knee, increased pain with passive abduction of the lower leg, and swelling on the medial side of the knee, with petechiae appearing after a few days. Knee movement will be restricted. 6, improper exercise Some elderly people like to hike, but if they do not prepare for the activity or exercise too much, it can also cause joint pain. Especially people who suffer from synovitis or osteoarthritis, more likely to cause joint disease attacks or aggravation. In mountain climbing, when descending a mountain, the weight of the whole body is put on one knee joint and the pressure on the knee joint is several times higher than when standing normally. The same situation occurs when people go up and down stairs. 7, bad walking habits For example, often wearing shoes that do not fit the foot or walking long distances in slippers and high heels can put the knee joint in an abnormal state of stress for a long time, causing chronic damage to the knee joint and causing knee pain. Second, the lumbar spine, lumbar spine or hip diseases cause knee pain There are three nerves that dominate the lower limbs, they are the femoral nerve, sciatic nerve and the closed foraminal nerve. People are familiar with sciatica, which to many is synonymous with lumbar disc herniation. The femoral and foraminal nerves are unfamiliar. In fact, lumbar spine pathology that affects the femoral and sciatic nerves can cause symptoms in the lower extremities. These symptoms include pain, muscle atrophy, soreness and swelling, coldness, numbness, coldness, heaviness and fatigue. The femoral nerve comes from the upper lumbar spine and innervates to the medial aspect of the knee and the front of the lower extremity. Any lesion in the tissues through which the femoral nerve passes can cause knee pain. From clinical experience, knee pain caused by lesions of the upper lumbar spine involving the femoral nerve is common, and most patients with knee pain can find obvious pressure points in the lumbosacral region, lateral hip (vastus fasciae, gluteus maximus, gluteus minimus), hip and groin (internal retractor muscle group). The effect can be immediate. Some patients with lumbar disc herniation also have symptoms such as knee pain and soreness, and when the lumbar disc herniation is cured, the knee pain symptoms will also be cured. In daily life, most knee pain is not caused by trauma. Prolonged exposure to cold and large temperature differences are the main causes of knee pain. Especially in the fall, when cold and warm temperatures alternate, low temperatures or large temperature differences can cause muscles and blood vessels to contract, causing knee pain. If you encounter this situation, the first thing you should do is to keep as warm as possible, you can use hot compresses; the second thing is to reduce the amount of exercise and let the joints get rest. If the above methods do not make the knee pain better, then you should go to the hospital to clarify the cause of the knee pain so that it can be handled and treated correctly.