The shoulder (glenohumeral joint) is a ball and socket joint. The ball is at the top of the arm bone (humerus). The socket is the glenoid which is part of the shoulder blade (scapula).
Shoulder replacement is a treatment option for shoulder arthritis where the patient remains symptomatic despite appropriate non-operative treatment.
The worn-out surfaces of the humerus and glenoid are replaced usually with metal or ceramic or plastic (polyethylene) components.
Two main designs of shoulder replacement may be used;
1) Anatomic shoulder replacement
This design mimics the natural shape of the shoulder joint, and works best when the rotator cuff tendons around the shoulder are in good condition.
The humeral (arm bone) component may have a stem that goes down the middle of the bone. A ‘stemless’ design may be used (often in younger patients).
2) Reverse shoulder replacement
In this design, the ball and socket arrangement of the shoulder is reversed so that the ball part of the joint is attached to the glenoid and the socket part is attached to the humerus. This design is usually selected if there is a rotator cuff tendon tear in the shoulder as well as arthritis, as it allows the deltoid muscle on the side of the arm to move the shoulder more efficiently.