Reverse Total Shoulder Arthroplasty has been introduced in recent years to overcome instabilities presented by hemi- and total arthroplasty. This device design reverses the ball and socket design of the natural shoulder, moving the cup (“socket”) to the upper arm and the ball to the scapula. Many Reverse Shoulder Replacements (RSRs) are designed as modular components that either screw or press fit together in an assembly to facilitate future revisions and enable customized fitting to different patients. However, modular RSRs are often implanted in patients with proximal humeral fractures who thus exhibit little to no bone support around the upper half of the implant. With lack of bone support and implant modularity, the stem has a tendency to unscrew from the cup portion of the implant. As a result of unscrewing, the RSR can potentially fret at the screw threads, leading to metallosis or even device fracture. The goal of the project is to reconstruct different RSR modular assemblies and assess their propensity for fracture as a result of unscrewing.