The failure rates are in the 2 to 4% (over a 10 to 15 year period or so) and that is generally associated with metallosis, thus all the fuss about metal ions. I know, why are we so worried about such a low number? Anyway, I don't think anyone has related failures to plain and simple-excessive wear. The wear that is talked about tends to be related to poor placement of the components. I think the study that you are looking for and many of us are looking for, is a study that takes all of the perfectly placed HRs and takes the millions of cycles per year that most extreme athletes are pushing and then compares failure rates. I'm not sure it exists and I'm also not sure that it's something most experienced surgeons think is even valid. I suspect that there is a general consensus amongst the most experienced surgeons that is, if you have a decent sized component, a well placed component, a decent CoCr alloy, continue with high level of activity, you may well outlive your prosthesis.
In short, I don't think many of us are planning for a revision, or THR. The problem is, we are relying on science and we only have about 15 to 20 years of sound data to rely on. That is partly why we wonder about the potential to have a revision. Throw a little NY Times and a lawsuit into the mix and then the sky is falling. I believe that the 96 to 98% success over the last 10 to 15 years will someday be more like 95% over the next 40 years. Why would McMinn's 20 year patient all of a sudden need a revision?