Reverse Shoulder Prosthesis Prospective Multi-Center Study

Inclusion Criteria: * Subject must be a candidate for a total shoulder joint replacement * Subject must be diagnosed with one or more of the following conditions: Irreparable rotator cuff tear with gleno-humeral arthritis; Failed rotator cuff surgery with gleno-humeral instability or antero- superior escape; Failed shoulder replacement surgery * Subject has a functional deltoid muscle * Subject's joint must be anatomically and functionally suited to receive the selected implant * Subject is 60 years of age or older (≥ 60 yrs of age) at time of consent * Subject is likely to be available for all study visits * Subject is able and willing to sign the informed consent and follow study procedures * Subject is not pregnant Exclusion Criteria: * Subject has a non-functional deltoid muscle * Subject has a mental condition(s) that may interfere with the subject's ability to give an informed consent or willingness to fulfill the study requirements (i.e., severe mental retardation such that the Subject cannot understand the informed consent process, global dementia, prior strokes that interfere with the Subject's cognitive abilities, senile dementia, and Alzheimer's Disease) * Subject is a prisoner * Subject has high levels of physical activity (ex. competitive sports, heavy physical labor) * Subject is pregnant * Subject has an active infection or sepsis * Subject has loss of ligamentous structures * Subject has a history of alcoholism or other addictions (current or past) * Subject has muscular, neurological or vascular deficiencies which compromise the affected extremity (i.e., Parkinson's Disease, Syringomyelia and Multiple Sclerosis, Charcot joints) * Subject has severe glenoid bone loss * Subject has known materials sensitivity (to metals) * Subject is younger than 60 years of age (\< 60 years of age) at consent