Purpose: The purpose of this retrospective studies is to evaluate the real effectiveness, with clinical and radiologic evalutation, of the eccentric glenosphere and also how a correct position can prevent the scapular notching.

Material and Methods: We inplanted in 18 patients, with eccentric arthopaty, a 36 mm eccentric glenoshere.24 months’ clinical and radiographic follow up. All patient were assessed preoperatively and postoperatively with the Constant Score. In the post-operative radiographic control we have taken in consideration: the presence of notching, psna (prosthesis-scapular neck angle), pgrd (peg glenoid distance), glenoid inclination, craniocaudal position of the glenosphere in relation to the glenoid.

Results: The ROM increased in all level. All of the 18 shoulder had no notching. The craniocaudal position of the glenosphere in relation to the glenoid is 4,3 mm. The PSNA was 92° and the PGRD was 21.2.

Conclusion: The inferior scapular notching is the most important complicance of reverse prosthesis. The results of our study indicate that : the correct positioning of the metal back, at the center of the glenoid (better biomechanics stability), without overhang and with eccentric glenosphere, permits to lower the center of rotation of 4 mm avoiding the notch and so increasing the adduction and abduction range of motion.