As with joint replacements elsewhere in the body, ones for the shoulder involve removing damaged tissue and installing an artificial joint, usually made of metal and plastic. Shoulder replacements are not as common as those for the knees and hips. Yet, the surgical procedures and man-made joints for shoulders are every bit as sophisticated and reliable. Replacements commonly are required due to fractures or chronic conditions, like osteoarthritis and rheumatoid arthritis. Patients may need a new joint, if they are experiencing pain, restricted movement, stiffness, atrophy of shoulder muscles and grinding or catching sensations in the shoulder. After replacement, many patients report reduced pain and greater range of motion. Rehabilitation always is an important part of the recovery process.