The surgical replacement of the shoulder joint is the third most common joint replacement after replacement of the hip and knee joints.

The shoulder is a ball and socket joint.

The shoulder 'socket' is shallow to allow a greater range of movement at the cost of bony stability.

Shoulder joint replacement can be:

• Partial: one particular surface is replaced - the humeral head; also known as Shoulder Hemiarthroplasty.
• Total: both particular surfaces are replaced by prostheses; also known as Shoulder Arthroplasty.
• Reverse: both particular surfaces are replaced but with the 'ball' on the glenoid and the 'cup', or 'socket' on the humerus.