When a patient develops disabling symptoms as a result of arthritis, tumor, or other condition that destroys the joint, a joint replacement can be considered.   Arthritis is the most commonly seen in the knee and knee replacements are then the most common joint replacement.  However, shoulder replacements are also available for patients that develop severe pain and dysfunction in their shoulder.  For some patients, only the humerus or “ball” of the shoulder is replaced or resurfaced.  This is called a hemiarthroplasty.  For most, a total shoulder replacement, which involves replacing the humeral head or “ball” with a metallic implant and the glenoid or socket, with a plastic socket, is an option to improve pain, motion, and function.  For others, particularly those with severe deformities, severe fractures, torn or poorly functioning rotator cuff tendons, and those that have failed a previous joint replacement, a reverse shoulder replacement is probably a better option to consider.  In the reverse shoulder, the glenoid or socket, is milled down and a metal ball is secured to it.  On the humeral head side, or ball side, the head is reamed out and a socket is fixed in place.  Thus, a backward or reverse shoulder.