When my ankle was bothering me I thought pedaling with the arch of my foot would put less strain on the sore ankle. But switching to clipless seemed to alleviate, not worsen the condition. I don't think the clipless pedals are the reason my ankle got better, but they didn't prevent healing. I assume you use toe cups to keep the ball of your foot over the pedal spindle. I don't think the ability to vary the fore/aft position of your feet while cycling is necessary or important, but I could be wrong.