Over the last year, I have developed quite a bit of knee pain that was not caused by cycling. I can't say whether my pain is similar to the OP's, but for what it's worth I switched to Speedplay Frogs. Since, other than the chronic pain, I have none of the additional discomfort that I was getting riding on other systems. Prior to my knee pain, I was happy with the SPDs, but then couldn't get enough float. Tried ATACs and those were worse. My doctor is a cyclist and recommended the Frogs. They work great for me.