Thanks for the tips physiofixme.

I am quite certain that I have subtalar impingement anterior, behind and perhaps even posterior to the lateral malleolus. Probably in the sinus tarsi region too. I also have passive inversion and I am jammed in that slightly inverted position even when weight bearing. I don't believe that my subtalar joint moves at all.

This doesn't seem fully consistent with what you describe yet I have found one link which uses STS and lateral subtalar impingement interchangeably.

Is it possible that during an inversion sprain tissue has become trapped in the subtalar joint? Can this tissue impingement be described as Sinus Tarsi Syndrome?
Additional Comment I forgot:
On second read, that link seems to make a distinction. Therefore I have lateral subtalar impingement and not sinus tarsi syndrome. I believe I have localised it well enough for my surgeon. 30 days to go for my fifth and hopefully last time.

Any other tips are appreciated!