In reply to Anthony Hirst:
I have a 6 year old metal resurfacing (big ball) and a 4 year old ceramic/ceramic replacement (medium ball) and with both I was bouldering carefully at 8 weeks and jogging. There are forums for hippies, both American, HipRunner and SurfaceHippy and dislocation is almost never mentioned, I can only remember one unfortunate who had serial dislocations but he was already operated on multiple times.
It seems to be a rule not to bend beyond 90 degrees for the first few months but many surgeons do not bother to advise this nowadays - and the pain would probably stop you anyway early in your recovery.
I could detect my ceramic bearing 'floating' a tiny bit whilst sitting a few days after the op but this went away very quickly - that leg was lengthened by 4 or 5 mm, maybe as a way of keeping the ligaments/tendons with a bit of extra tension to avoid dislocation?
None of my acquaintances has had a dislocation despite being active climbers or bikers. I seem to be the only one that has carried on running to any extent - most people's surgeons advise against running but mine said I would not be able to break my ceramic hip!
Good luck!