[The total shoulder prosthesis]

Prosthetic shoulder replacement is impeded by two main obstacles: the articular cavity is very shallow, and the small glenoid surface rests on a narrow neck to which prosthetic pieces are difficult to attach. The principal, currently used prostheses are non-retentive models which reproduce the anatomy of the joint. They differ from each other mainly in the glenoid piece pattern which may be sealed only to the glenoid cavity or also fixed onto the acromion. On the whole, the clinical results reported are encouraging, particularly as regards the absence of pain, but the radiological course of the glenoidal sealing is a source of concern. Obvious unsealing is rare, but cracks between bone and cement are very frequent and some of them become wider as time goes by. In addition, there is still no satisfactory solution to the problem of big rotator cuff tears. This type of prosthesis must be envisaged with caution and should be reserved to very painful shoulders, but it would be wise not to wait until the rotator cuff is destroyed. The best indications are glenohumeral osteoarthritis, rheumatoid arthritis and necrosis of the tumoral head.