Hi Bob, and welcome to BoneSmart. You haven't filled in your location when you registered so I can't tell where you are.
That's bad luck, having two get loose in so short a time. A few questions to help me out though
What's your age?
Are you a big chap? or very big chap! - engage in any sports or other activities?
Have you had the same surgeon throughout?
There's a new(ish) speciality that is evolving out of joint replacement and that is surgeons who only do revisions. A revision is not just like redoing the original op. There are special implications and issues to be addressed. Therefore, I always advise people to go to such surgeons - revision specialists. These are the guys all the 'ordinary' surgeons send their problems to. It takes a bit of ringing around and asking but, were I in your situation, I would want a top notch (in the eyes of his peers, not the general public) surgeon to do a third revision.