In some embodiments, the present invention provides a reverse shoulder glenoid prosthesis which supports the attachment of multiple different types of modular attachments that can: 1) provide additional scapular fixation (ie external to the glenoid) in order to improve glenoid implant fixation in cases of severe bone loss/fracture, 2) provide joint line lateralization to improve tissue stability in cases of severe glenoid/scapula bone loss, 3) facilitate use and containment of glenoid bone graft in cases of severe glenoid/scapula bone loss—particularly in those cases in which the glenoid defect is uncontained/peripheral 4) achieve glenoid fixation while at the same time reconstructing the scapular bone in cases of scapula fractures, glenoid fractures, and/or acromial fractures, and 5) provide improved rTSA joint biomechanics, particularly posterior rotator cuff efficiency by changing the line of action of the infraspinatus and teres minor muscles to improve their muscle tension, and also increase each muscle's external rotation and abduction moment arm lengths.