my dad had a bad accident at 23 years old and shattered a lot of bones, this lead to athritis (sp) at a very early age, he had his first hip replacement in h is late 20's and has since had 14 hip replacements, and a knee replacement, we nicnamed him the bionic man.
after the first replacement he led pretty much a normal life, still kicking a ball around in the garden with my brother etc, that hip lasted 15 years and was told if he had taken things a bit easier it would have lasted alot longer.