The causes of knee swelling and pain are as follows: 1. Knee infections can be caused by tuberculosis and general septic infections, which are usually accompanied by swelling, pain and limited movement of the knee joint, sometimes accompanied by an increase in body temperature and general weakness. 2. Gout can cause knee swelling and pain, as well as redness and swelling of the knee joint. 3. Strain on the ligaments around the knee joint. This can lead to damage to the ligaments around the knee, tears or damage to the joint capsule, which can also cause soreness and pain in the knee. 4. The most common cause of soreness and pain in the knee is trauma to the cartilage of the knee and damage to the meniscus, which can cause soreness and pain in the knee. Therefore, if the knee is sore and swollen, and if there is no relief within a short period of time, it is important to go to a regular hospital and have an X-ray, CT or MRI examination of the knee joint. If necessary, blood tests should be taken to clarify the diagnosis and choose a reasonable treatment to provide timely and effective relief of the sore and swollen knee.