It's boring as hell, but aqua-jogging (not THAT kind of jogging
) can help maintain run fitness when you have a bum ankle.
I did a few sessions last summer, but thankfully it got well enough that I could ride the bike again after less than 2 weeks, and another week later I started doing VERY short and VERY easy runs on grass and smooth trails.
I'm taking swim lessons from a local (NYC) swim guru named Doug Stern.
He also does aqua-running classes, and there is info on his website about what it is and how to do it, here
click on the deep water running link for your info.
(warning, there's a large pic of him that pops up, it's kinda scary. He's actually a really cool dude, but damn that's some pic.
Did you look into A.R.T.? Since you are still at only 50%, my guess is no.