Swelling of the knee after a fall may be caused by local soft tissue injury, or it may be caused by knee fracture or dislocation, and the way to reduce the swelling includes physical therapy, medication and surgical treatment. 1. Soft tissue injury: first of all, after the fall, we need to carry out knee braking, ice, elevate the affected limb and other treatments; after 72 hours, we can choose hot compresses, local massage, microwave and other ways to alleviate the symptoms; we can also choose static mannitol, sodium heptapartite saponin and other drugs to reduce the swelling of the treatment. 2. Knee fracture or dislocation: patients with dislocation or good alignment of fracture line need to be actively manipulated and fixed with plaster or support; patients with comminuted fracture or suspected dislocation causing ligament tear are recommended to undergo surgical treatment, which includes incision and reduction internal fixation, arthroscopic exploration surgery and ligament repair or reconstruction surgery. For the same disease, patients with different physical conditions and at different stages of the disease, the treatment methods are different and should be standardized under the guidance of a doctor. All of the above medications should be used under the guidance of a doctor, avoid self-medication.