Arthritis of the glenohumeral joint accompanied by an irreparable tear of the rotator cuff can cause severe pain, disability and loss of function, particularly in the elderly population. Anatomical shoulder arthroplasty requires a functioning rotator cuff, however, reverse shoulder arthroplasty is capable of addressing both rotator cuff disorders and glenohumeral deficiencies. The Aequalis Reversed Shoulder Prosthesis design is based on two bio-mechanical principles by Grammont; a medialized center of rotation located inside the glenoid bone surface and second, a 155 degree angle of inclination. Combined, they increase the deltoid lever arm by distalizing the humerus and make the prosthesis inherently stable. 24 consecutive