Total shoulder replacement (also called shoulder arthroplasty) is a surgical procedure to replace damaged parts of the shoulder using prostheses (artificial replacements). Replacement of the shoulder joint are procedures where the surfaces of the joint, normally made of bone covered with cartilage, are replaced with parts made of metal and plastic. The operation is sometimes called arthroplasty. In the shoulder, often only the upper arm (humeral) side of the joint is replaced.