In a healthy joint, the round head (ball) of the upper arm bone fits into a shallow socket in the shoulder. Shoulder replacement removes damaged areas of bone and replaces them with parts made of metal and plastic (implants). This surgery is called shoulder arthroplasty (ARTH-row-plas-tee).
One of the most common surgical procedures for the shoulder is a rotator cuff repair. There are many ways to do this, and most surgeons have their preferred techniques.
In a typical shoulder replacement, a plastic lining is attached to the socket to allow smooth movement. The surgeon removes the top of the arm bone and inserts a metal stem with a ball on the end. However, if the rotator cuff is severely damaged, the joint may not be stable or work properly.