Kathyborn, The original poster Ezas can better answer, but revision surgery for any of these joint replacements usually means that something did not go well with the initial replacement, and ortho has to go back in to revise, correct, repair, etc. The same can happen with hip replacement. Of course, it is more "delicate" and challenging to do revision, but thank goodness Ezas's revision surgery turned out better. So happy about that. One other note, if revision surgery is necessary, be sure to select an ortho who specializes in revisions surgery of whatever joint is being operated on. It takes real skill to do this kind of surgery.