The swelling usually goes down in about 2 weeks after knee free body surgery. Knee free bodies are usually caused by aging of the joint and degeneration of the cartilage, resulting in the cartilage layer partially peeling off, leaving the joint to form free bodies. Once a free body is present in the knee joint, the only option is to remove the free body completely through surgical treatment. After arthroscopic surgery for a joint free body, with appropriate treatment, swelling of the joint and lower extremity usually resolves gradually in about 2 weeks, or longer in some cases, such as when it is combined with other conditions in the joint, or when the surgery is more complicated and relatively more invasive. The following methods can help to promote the reduction of swelling. 1. Elevate the lower limbs: try to elevate the lower limbs above the heart level when resting, which can promote the blood circulation of the lower limbs through the effect of gravity, which is conducive to the reduction of swelling. 2. Functional exercises for the muscles and joints of the lower limbs, such as isometric contraction training of the quadriceps, can also promote swelling. 3. Local cold compress: it can promote the swelling of joint tissues to subside. 4. Physiotherapy: such as baking electricity, etc., can reduce local swelling and pain. If the swelling of the joint or lower limb is obvious or lasts too long after knee free body surgery, it is recommended to have a follow-up consultation in time to avoid delaying the condition.