Indications for total shoulder arthroplasty (TSA) require that the patient have a functioning rotator cuff to stabilise the glenohumeral joint. Without rotator cuff integrity the prosthesis will be unstable and the functional result will be less than expected. Physical exam can be difficult in the arthritic shoulder as contractures will limit the range of motion needed to adequately exam the rotator cuff status. The diagnosis can help as osteoarthritis has a 5% incidence of rotator cuff tear while rheumatoid arthritis has an incidence of greater than 40%. MRI can be obtained to determine the rotator cuff status before arthroplasty is performed but may not be necessary. Most total shoulder implant companies have both reverse and anatomic implants available. More recently the uses of platform stems that can be used with either RSA or TSA have been available. With this development in prosthetic design it is no longer necessary to determine the status of the rotator cuff before surgery. The surgeon can make the decision at the time of surgery which implants RSA or TSA will be necessary based on the status of the rotator cuff. There have been recent reports of longer follow up of TSA patients that had fatty atrophy of the infraspinatus muscle that had rotator cuff tears at 10–15 years. MRI may still be warranted in the older individual that is being considered for TSA to determine the quality of the rotator cuff musculature.