Addendum of surprise
Wait, my ankle doesn't hurt.
I walked four miles yesterday, most of it on relatively uneven grass and packed dirt. There were notable uphill bits.
I have walked sufficiently this week that I've overstressed my achilles tendons and the backs of my heels now hurt like a git (I had to go down the stairs crabwise this morning).
Manky, however - you know, the arthritic ankle with the bit of missing bone - is fine. A little tired, but fine.
O.O