Lateral knee pain consider lateral soft tissue injury, lateral collateral ligament injury or inflammation, lateral meniscus injury or degeneration, knee osteoarthritis. 1. Trauma or sterile inflammation:Trauma can lead to lateral knee soft tissue injury, lateral knee pain, accompanied by local soft tissue swelling. Lateral collateral ligament injury or inflammation, trauma can lead to lateral collateral ligament injury, positive lateral stress test, with knee instability. Long-term repeated knee activities can cause friction of the lateral collateral ligament of the knee, resulting in aseptic inflammation and pain. 2. Meniscus injury: the lateral meniscus of the knee joint is damaged or degenerated, resulting in obvious pain on the lateral side of the knee joint when it is flexed or extended, and in serious cases, it can be accompanied by popping sound, and there is obvious compression pain in the lateral knee space. 3. Osteoarthritis: osteoarthritis of the knee in the elderly, there will also be lateral knee pain, but also medial pain, X-ray shows narrowing of the knee joint space and osteophytes. There are many causes of lateral knee pain, if it is difficult to relieve, it is recommended to actively seek medical attention and treatment under the guidance of a physician.