Knee pain after running may be caused by inflammation of tendons, cartilage damage, joint sprains, ligament tears, and so on. It can be treated by non-steroidal anti-inflammatory and analgesic drugs, lubricant injection, local ice and surgery. 1. Inflammation of tendons: after running, the tendons of the knee will be repeatedly contracted by friction, local congestion and edema, the formation of aseptic inflammation, causing local pain symptoms. The pain can be relieved by taking anti-inflammatory and analgesic drugs such as ibuprofen extended-release capsules and diclofenac sodium. 2. Cartilage damage: If there is obvious cartilage damage after running, you can add nutrition to the knee joint, such as injecting lubricants like chitosan and hyaluronic acid to relieve pain. 3. Joint sprains: improper joint activities after running can cause sprains, first of all, reduce knee activities. When pain symptoms are mild, local cold compresses can be used to relieve pain and reduce swelling. When the pain is severe, you can take the analgesic acetaminophen to relieve the symptoms of local pain and swelling. 4. Ligament tear: If the ligament is partially torn after running, it does not affect the stability of the knee joint, and there will be pain symptoms, and can be fixed with a plaster, and most of the cases can be healed by themselves. If the ligament is completely torn, the knee joint is unstable and serious pain, open surgery or arthroscopic ligament repair and reconstruction surgery can be considered for treatment. When the knee pain after running, it is recommended to go to the orthopedic hospital in time, to clarify the cause of the disease, under the guidance of the doctor to use drugs and surgical treatment.