A Post-Market Clinical Evaluation of the ReUnion TSA System

Inclusion Criteria: * Subject is willing to sign the informed consent. * Subject is willing and able to comply with postoperative scheduled clinical and radiographic evaluations. * Subject is male or non-pregnant female and 18 years or older at the time of surgery. * Subject has one or more of the following: * Aseptic necrosis of the humeral head * Painful, disabling joint disease of the shoulder resulting from degenerative arthritis, rheumatoid arthritis or post-traumatic arthritis * Failed previous total shoulder replacement, resurfacing or other procedure Exclusion Criteria: * Subject has an active or suspected latent infection in or about the shoulder joint. * Subject has mental or neuromuscular disorder which would create an unacceptable risk of prosthesis instability, prosthesis fixation failure or complications in postoperative care. * Subject has bone stock compromised by disease, infection or prior implantation which cannot provide adequate support and/or fixation to the prosthesis. * Subject has anticipated activities which would impose high stresses on the prosthesis and its fixation. * Subject is obese such that he/she produces a load on the prosthesis which can lead to failure of fixation of the device or to failure of the device itself. * Subject has absent, irreparable or non-functioning rotator cuff and other essential muscles. * Subject has concomitant disease(s) which may significantly affect the clinical outcome. * Subject has traumatic or pathologic fracture of the proximal humerus.