I have never understood that mentality!

Here you are, semi-crippled, in pain, and the doctor says, "Let's wait until you're old enough that you won't even need the knees, then we can put in new ones. No sense in putting them in while you're still young enough to enjoy them."

My wife went through similar battles with her doctor before finally convincing him that she wanted to do more than just sit around on the porch in her rocking chair watching the neighborhood kids at play. You know, things like hiking, kayaking, or (heaven forbid!) actually walking without pain.

Yes, I know -- they don't know for sure how long these replacements will last, but consensus seems to be at least 20 years. Since technical/medical progress over time has historically been asymptotic by nature, I am quite convinced that 20 years from now the problem of replacing worn-out prosthetic knees will have been solved quite handily, probably through stem-cell regeneration techniques.

tanstaafl.