Only thing I would look hard at, life expectancy of replacement vs current age and expected age and quality of life etc... IE wait a few years and never have to have it down twice, I might consider...
Back in the 80's they were saying the service life of a total knee was about 10 years. However, when I had my total knees done ('05 and '06) they had found that the median service life for those 1980's prostheses was 27 years and growing. The prostheses they're putting in now are expected to last even longer. Mine have a Teflon bearing in them that can be replaced with minimal surgery (basically, a knee scope).
Basically, the new TKA's will outlive you.
