*2.1. Study Design*

A retrospective multi-center review was conducted on rTSA cases performed by 5 independent surgeons from 5 separate institutions between June 2013 and January 2018. Institutional review board permission was obtained prior to initiation of the study (IRB 17-202-2). Patients who underwent primary rTSA using an implant with a 135◦ humeral inclination for the treatment of cuff tear arthropathy or primary glenohumeral arthritis with a minimum follow-up of 2 years were included in the study. Patients were excluded if they underwent rTSA using a 155◦ prothesis design, were revision cases, had concomitant fractures of the humeral head or glenoid requiring surgery, or had neurovascular injuries.
