I have a bad left hip I injured 25 years ago, and it's been aching ever since. It gets a little worse every year, but so far I don't need meds for it. Three years ago I had it X-rayed and all the Dr said was "you have moderate arthritis". I don't need a hip replacement yet, but like you, I know that day will come. Because of that, I talk to people who've had them all the time. What I've learned is this:

- You know it's time to get it when the pain keeps you awake at night, regardless of sleep position. Or if you need ibuprofen every day just to be comfortable, it might be time.
- A hip replacement only lasts 10 years, so wait as long as possible to get one.
- Joint replacement technology makes vast improvements about every ten years, so wait as long as possible and hope the technology improves.
- There are different techniques for hip replacement, and the more expensive techniques are better and longer lasting, but your insurance will likely only cover the cheaper options. So save your money to get the best possible option.

About five years ago I was doing an Olympic distance triathlon, and a 62 year old guy came pedaling past me. Being 15 years younger at the time (and cycling is my best discipline), I was impressed, and pulled up beside him and told him so. He said thanks. Later in the race I noticed him leaving the bike-to-run transition at the same time as me, and said "I'm a terrible runner, so you'll be leaving me behind now". He said "No, I've had both hips replaced, and I'm not even supposed to be running, so I'm sure you'll be leaving me behind". And sure enough, I did, even though I was only running a 9 minute pace. Conclusion: the hip replacement was fine for cycling. Not so much for running.