There are a fair amount of wound infections that are associated with joint replacement surgeries, too. I personally, know of a half dozen friends that experienced this and some had to go back for complete revisions, which is a horrendous experience.
Gary
Gary what the hell kind of doctors or hospitals are your friends going to. I have had two total knee replacements in a 2 year time period 14 years ago and have seen dozens and dozens of people during therapy, none of whom had the same experience as your six friends.
I am not saying anyone should jump into surgery as all avenues of treatment should be explored, but I am happy I had mine done and even happier it wasn't by the same doctors or in the same hospitals as your friends.