I don't know OP's situation, but I've got arthritis stemming from a 1968 cartilage removal (left knee lateral meniscus). It started giving me trouble (soreness / mild swelling) about fifteen years ago; I was running two miles a day at the time. On the advice of an orthopod I started talking glucosamine pills and the symptoms disappeared. They haven't recurred, although admittedly I don't run as much now. Glocosamine may extend your time until the surgery becomes necessary.

I'm no expert, but I'm told the short life of certain knee products is often due to the recipient trying to do everything he / she did before the surgery (running a LOT; even gardening). Taking things a bit easier - perhaps transitioning to bicycling, for example - may extend the life of the implant. As long as you're not in pain or severely restricted in activity, waiting seems to be a good choice. The implants and surgical techniques appear to be improving continually.