Pedal system advice

I used to use black look delta cleats as they felt more secure but unclipped more easily.  They did actually have a little float, but it was against resistance, which was a massive improvment over free float uphill or in sprints. Now I use Time Espressos, which are secure but very light to get out of. Movement required to unclip is pretty similar though, so that may not help. I never got away with unlipping inwards as my foot fouled the bottles (I have VERY big feet). Try lots of systems if you can - it's going to be individual..

Look keo black cleats have zero float. I unclip inwards at the top of a stroke (i.e., if I unclip when my foot is at 12.00 o'clock, I go inwards). When I am at bottom I unclip outwards. No knee issues but weird.

I got no float cleats and the difference is tremendous, and they do clip out easier than with float and as Welsh Boy said has improved knee pain.

As someone has said earlier, can you unclip inwards, I know you shouldn't but it's a habit that I just can't break now !

There's a Speedplay Light Action version, worth a try.

How about cleats without any float?  Take your time and set them up properly and you dont need float.  Before I am told that I am wrong, we rode for years with shoe plates which fitted over a pedal frame, there was no float whatsoever in that system and i didnt ever have a problem and knee pain wasn't a common complaint until clipless pedals first appeared.

Have you tried using an inward action instead of out as that works as well.

SH56 SPD multi-release cleats will allow you to get out of the pedal by sliding your foot off sideways.

Pair that with the aforementioned Click'R pedals, or "trekking" pedals such as the Deore XT PD-T780/T8000.

I have a pair of the T780s, and subsequently bought a pair of PD-M530s, which are the cheapest "standard" SPD pedals with an external cage. Even on the SH56 multi-release clceats, I noticed the spring tension on the M530s is much stiffer compared to the T780s - it takes more effort to get out of them. Shimano does say that for Click'R pedals (and I believe to some extent the T780s as well), the spring release tension is ~60% less compared to their normal SPD pedal lineup.

You need to pop to a shop and arrange to try several different systems to find which is easiest to clip in/out.  Well worth the experience given it could cost a small fortune to buy pedals only to find out they are not suitable.  

Keep cycling, even with standard pedals if necessary.  Hopefully you ankle will improve, mine has, and is better after 2 years of cycling.

I' d agree with the other 2 posters.  On my commuting bike I have Shimano's SPD click-R pedals which have a very light release and come with the multi-release cleats, so that in an emergency I can just pull up sharply on the pedal and clip out.

As your heel gets better you can then start gentle rotation outwards again to get back into the normal routine - after all you won't want to develop too many bad habits in muscle memory - could be embarrasing when you move back to SPD-SL eventually...

SPDs with multi-release cleats? Don't need the full heel kick to disengage - a yank in any angle will do it. Tension can be adjusted. Also not that expensive for pedals and cleats to try out (adds up if you need different shoes too, though)...

I've got speedplay zeros too and you still need the heel flick to disengage - though you can adjust the float.

My SPDs are so loose, a decent yank disengages them! 

You could straighten/turn the cleat, so that the disengage point is closer to your normal foot position?