Thanks for your questions:
1. If you have a reverse shoulder replacement and it goes its life span, whatever number of years it might be, Can you have another reverse shoulder replacement done?
Yes---so long as there is no active infection or severe loss of bone stock. Your question really gets to the question of "Do you burn a bridge in having a Reverse now, as opposed to putting it off and living with pain?"
In my experience with primary Reverses as well as Revisions to a Reverse because of failed Hemiarthroplasty, pain relief is nearly complete; and a secondary benefit is the ability to raise the arm in the plane of the scapula to at least 90 degrees, and more commonly to 120-135 degrees. This greatly improves function. Now, if there is a complication such as instability or loosening, these can be addressed by reoperation. However, as techniques improve----these complications have been diminishing.
I say to my patients that our goal is a 10-15 year period of pain relief and improved function. Though it appears that function may begin to decrease after around 7.5 years (this is based on an outcome study by Dr Giles Walch, who uses a Grammont design). patients are still doing better thn before the operation.
2. Is there a report that you can direct me to that compares the life expectancy of JCO/Encore vs. other models?
No. But I have attached an article published in the J Shoulder and Elbow Surg in jan 2011 which addresses such things as glenoid loosening and scapular notching.
Visit this link:
http://www.rearmyourself.com/article...20Arthroplasty
The survival rates of an anatomic type of total shoulder design at 10 years is 92%; a hemiarthroplasty is more like 72%. I expect that with current techniques the Primary Reverse will have a 10 year survival in the 90's--------but that function may decline over time. The humerus should be no different with the Reverse; the glenoid baseplate, by contrast, might loosen with time----in that regard, the lower rate of scapular notching with the DJO design as compared to the Grammont design may bode well for the former regarding survivability.