I assume you meant UCL replacement. I've heard of moving the Ulnar Nerve but not replacing it. Some have said this is the same thing that Rivera had done back in the early 90's. The description of that procedure varies. Some say they just moved the Ulnar Nerve and some say they cleaned up some fraying of the ligament. Perhaps they did both.
My question is what do they do to reinforce the stretched but not torn or not fully torn ligament?
Maybe Steve-3P could check with Dr. Andrews and let us know.