Thanks lani62 for taking the time to post some excellent comments.
I think in current climate, a very rapid payback (< 2 yrs) will be essential for any putative financier.
i take it TKR is total knee reconstruction.
It does sound like quite a project, I have a clicking knee so have a minor vested interest; after your comments I may leave it clicking for a bit longer.
Hoping yours improves rapidly from here.