Long-term Clinical Effectiveness of the Delta Xtend Reverse Total Shoulder

Inclusion Criteria: * Male or female subjects, aged less than 85 years inclusive. * Subjects who have cuff tear arthropathy, osteoarthritis with cuff deficiency, rheumatoid arthritis, post traumatic injury, or a need for revision surgery of a failed anatomic prosthesis in the left or right shoulder, which requires (total) shoulder arthroplasty. * Subjects with radiographic evidence of sufficient bone stock to seat and support the Delta XtendÔ Reverse Total Shoulder System. * Subjects who in the opinion of the Clinical Investigator are considered suitable for treatment with the Delta Xtend Reverse Total Shoulder System. * Patients with a life expectancy of greater than 12 months. * Subjects who are able to give voluntary, written informed consent to participate in this clinical investigation and from whom consent has been obtained. * Subjects who, in the opinion of the Clinical Investigator, are able to understand this clinical investigation, co-operate with the investigational procedures and are willing to return to the hospital for all the required post-operative follow-ups. Exclusion Criteria: * Male and female subjects aged 86 years or older. * Subjects with complete deltoid muscle palsy in the target joint as determined by clinical evaluation. * Subjects with active local or systemic infection or with a history of general or local infections in the target joint over the past 12 months. * Subjects with severe deformities, or tumours, that would impair fixation or proper positioning of the implant. * Subjects with no significant muscle, nerve or vascular disease. * Subjects with a pathology that, in the opinion of the Clinical Investigator, will adversely affect healing. * Known allergic reactions to implant materials (e.g. bone cement, metal, polyethylene) implant corrosion or implant wear debris. * Subjects with a known history of poor compliance to medical treatment. * Subjects who, in the opinion of the Clinical Investigator, have an existing condition that would compromise their participation and follow-up in this clinical investigation. * Women who are pregnant. * Subjects who are known drug or alcohol abusers or with psychological disorders that could affect follow-up care or treatment outcomes. * Subjects who have participated in a clinical investigation with an investigational product in the last month. * Subjects who are currently involved in any injury litigation claims.