The common causes of swelling of the lateral hamstring of the knee are trauma to the medial and lateral collateral ligaments as well as aseptic inflammation, which require general treatment, medication, physical therapy, and surgery depending on the specific condition. 1. Trauma: There is a clear history of trauma to the knee joint, resulting in strain to the medial or lateral collateral ligament of the knee joint. In the acute stage, it is necessary to reduce activities and apply cold compresses locally. In remission, the knee joint can be moved appropriately, local hot compresses can be given, and ibuprofen and other painkillers can be given when the pain is severe. If the ligament is seriously torn or ruptured, surgery is needed to repair it. 2. Aseptic inflammation: mainly due to strain, trauma and cold in the knee joint, the ligament has aseptic inflammatory reaction, which leads to swelling and pain. Treatment needs to minimize the knee joint activities, you can use non-steroidal anti-inflammatory drugs such as diclofenac sodium treatment, if necessary, you can also local injection of local anesthetic drugs such as lidocaine, and tretinoin and other glucocorticoid drugs. It is recommended that the patient go to the hospital, improve the auxiliary examination to clarify the condition, the drug needs to be used under the guidance of a professional physician.