Shoulder replacement surgery typically takes about two hours. You might receive general anesthesia, which means you’ll be unconscious during the procedure, or regional anesthesia, which means you’ll be awake but sedated. During the surgery, doctors replace the damaged joint “ball,” known as the humeral head, of the shoulder with a metal ball. They also place a plastic surface on the “socket” of the shoulder, known as the glenoid. Sometimes, a partial shoulder replacement can be performed. This involves replacing only the ball of the joint.