If you have rolled the same ankle more times than you can count, you already know the strange loneliness of it. The sprain heals, the swelling fades, people assume you are fine, and then a curb, a gravel path, or a misjudged step sends you down again.

If you are reading this, there is a good chance you have felt it: a stiff, deep ache in the middle or back of the foot that shows up after sport, long walks, or a day on your feet — and an ankle that seems to "give way" more often than it should.