Cortisone (steroid) injections are a common treatment for knee arthritis and inflammation. They deliver medication directly into the joint to calm swelling, relieve pain, and improve mobility. However, these injections can’t be done too often — overuse may damage the joint. For many patients, cortisone offers temporary relief that allows them to stay active and continue physical therapy. When arthritis becomes severe and injections no longer help, a knee replacement surgery may be the best optio