Background Early outcomes of reverse shoulder arthroplasty have been encouraging. Scapular notching remains a major concern. In an attempt to reduce this problem, newer glenospheres are available. This biomechanical study performed in vitro, assessed the micromotions of baseplate in different designs of glenospheres and the relative risk of loosening. Methods A dynamic shear force was applied to each type of glenosphere in various angles of abduction. The micromotion of the glenoid baseplate after 1000 cycles of dynamic loading was measured and compared. Results Eccentric glenospheres were shown to have increased micromotion compared to the concentric designs of the same size. The greatest baseplate micromotion (26.83 μm) was well within the accepted limit for osseous in growth into uncemented prosthesis. Discussion We therefore conclude that the magnitude of the increased micromotion is small and is not expected to adversely affect osseous in growth onto the glenoid baseplate.