The following measures can be taken to deal with a rattling knee bone flexion.1. The patient should first protect the knee joint, such as using an elastic bandage or knee brace to hold the knee joint in place. This should never be done by excessive movement of the knee joint in anticipation of eliminating this ringing, potentially aggravating the internal destruction of the knee joint. After doing so, it is important to visit an orthopedic or sports medicine department as soon as possible to identify the cause. In response to this ringing, there may be damage to the internal cartilage and meniscus of the knee joint, or there may be diseases such as synovitis, free bodies, or osteoarthritis.2. If the patient is confirmed to be free of disease after the visit, it is recommended that the patient do knee exercises under non-weight-bearing conditions, such as swimming.3. If the presence of several of these diseases is confirmed after the visit, and the degree is mild, conservative treatment may be done. Conservative treatment requires the patient to remain in bed for the near future and to be treated with anti-inflammatory, anti-swelling, and pain-relieving medications.4. If the above-mentioned diseases are confirmed to be present after consultation and are more severe, surgery may be required. For most knee diseases, arthroscopic surgery can be performed to explore and repair the joint. If severe osteoarthritis of the knee is present, joint replacement may be required. In cases where there is a free body in the joint, arthroscopic or conventional surgery is required to completely remove the free body.