A sprained foot that has been swollen for 20 days can be treated in several ways: a. An MRI of the ankle joint should be taken to confirm whether there is a ligament tear. If the ligament is confirmed to have a tear, then ligament repair surgery is required, such as ligament stop tear and performing stop reconstruction. If there is a complete tear of the body part of the ligament, an autologous tendon reconstruction surgery is needed to restore the stability of the ankle joint, and the swelling will disappear naturally. Second, if it is only a soft tissue injury and the patient does not brake in time to cause long-term swelling, the affected limb should be elevated and short-term treatment with hot compresses should be used to promote the swelling to subside. In addition, you can also assist in functional exercises of the ankle joint, mainly flexion and extension activities, to promote the swelling to subside and strengthen the stability of the ankle joint.