Knee pain and weakness: 1, may be because of rheumatoid arthritis or rheumatoid arthritis, inflammatory factors invade the synovial membrane and cartilage within the joints of the inflammatory reaction, causing knee pain and weakness symptoms. 2, may also be the knee gouty arthritis caused by uric acid abnormally high, the emergence of joints of the aseptic inflammation. 3, and there are also osteoarthritis in the joint cavity of the free body, can also cause Soreness and weakness of the joints.4. If the meniscus is torn and the torn tissue is stuck in the joint cavity, it will also cause the symptoms of soreness and weakness of the knees.5. The most common reason is the wear and tear of the cartilage, which is commonly seen in the wear and tear of the cartilage between the femur and patella, as well as the wear and tear of the cartilage between the femur and the tibia, which will lead to the symptoms of soreness and weakness of the knees. So if there is no relief within a short period of time, you must go to the regular hospital in time, improve the relevant examination, choose a more reasonable treatment method.