Total prostheses in degenerative shoulder pathology

Total shoulder arthroplasties (TSA) have significantly evolved over the past 30 years Anatomic total shoulder prosthesis of third generation reproduces carefully the anatomy of the joint surfaces and the centre of rotation of the joint, because of its adaptable cervico-diaphysal angle, on one hand, and is a low constraint prosthesis on the other hand. Clinical results are very good because the shoulder recover up to 97% of normal shoulder function. The long term results are also good with a first generation TSA survival rate of 87% after 15 years of follow- up. The indications of TSA are primitive or secondary shoulder arthritis without superior migration of the humeral head, or glenoiditis after hemiarthroplasty. TSA should be given up in case of un-reparable cuff tear and reverse prosthesis should better be chosen in this case. Reverse prosthesis have a humeral polyethylene "socket" positioned in valgus associated with an hemispherical glenosphere. The internal and low position of the centre of rotation, placed against the bony glenoid, converts the centrigugal forces, applied to the glenosphere, into centripetal forces. This leads to increase the deltoid action. Reverse prosthesis results are good and the shoulder recover on average 62% of the normal shoulder function. Long term follow- up results are also good with survival rate of 95% after 10 years of follow- up. However its future might be shorten by the scapular notch evolution. Several surgical techniques tend to prevent scapular notching: inferior and varus positioning or lateral translation of the glenosphere, varus positioning of the humeral socket. Reverse prosthesis indications are patients older than 70, with pseudo-paralysic shoulder, shoulder arthritis with superior migration of the humerus, post-traumatic shoulder or cuff tear after TSA.