The reverse total shoulder arthroplasty (RTSA) has quickly grown to become the most commonly used shoulder arthroplasty design;​ however, reports have shown evidence of RTSA failures related to polyethylene wear and damage. Therefore, the present work investigated the wear of crosslinked polyethylene (XLPE) in environments similar to that of an in vivo RTSA. Additionally, a computational model was developed based on a previous study of the shoulder motions obtained from a selection of typical patients with RTSA. This model quantified the amount of glenohumeral motion that an RTSA may be subjected to in vivo and provided an approximate value for the number of cycles that the RTSA-bearing shoulder may see annually. The in vitro RTSA wear simulation detected a significant decrease in polyethylene wear for XLPE in humeral cup liners compared with an earlier very similar study using non-XLPE. The computational model based on in vivo data suggested that smaller neck shaft angles of te implant might reduce polyethylene damage and also suggested that 1.25 million cycles in our joint wear simulator provided a good representation of 1 year in vivo. It is likely that the use of XLPE in the RTSA may reduce the number of failures related to wear.