After a knee sprain, there will be localized swelling, pain and painful joint movement limitation. After a knee sprain, cold compresses should be applied within 24 hours of the injury. Intermittent ice packs are used to prevent excessive swelling by promoting local vasospasm. In addition, you should go to the hospital for an MRI after the injury. If the medial collateral ligament and the anterior cruciate ligament are injured, surgery may be required. If there is no injury to the ACL and ACL, after applying cold compresses, you can consider putting the knee joint in a cast and adopting external fixation and braking to reduce the local swelling and local soft tissue injury. After the cast is removed, functional exercises of the knee should be performed to prevent limitation of knee movement.