I cannot create a summary of this article because the full text of the MedPage Today article about RFK Jr.'s surgery is not found in the search results provided. The information available is fragmentary and does not include sufficient detail about the rotator cuff surgery, return to work date, or other relevant medical data necessary to create a factual summary. In order to create an accurate summary as per your requirements, I would need the full text of the original article from MedPage Today.