I completely blew out my right ankle a few years ago, and it randomly sprains now and then. Basically, if I know I'm going on a longer ride that day I wear a support brace, (not the wraparound bandages but the dr. scholls velcro style,) or if I'm going to be spending a lot of time on my feet. An ounce of prevention is SO much better than a sprain because sprains take at LEAST 2 weeks to get back to normal. Just stick the brace somewhere in your backpack and forget about it until you need it. But discuss your situation with your physician, most importantly, I'm just an idiot! I'll tell you one thing, I used to be an mtb'er, and I've gotten head trauma, dislocated my shoulder,etc, but having an effed up ankle is the absolute worst, so take good care of it.