I have experienced the same thing. I was hit by a truck a couple of weeks ago, and I'm in the process of healing. My left knee is a bit sore, and when I rode my town bike with clipless pedals I had discomfort. The cleat evidently put my knee in a bad position, and unclipping hurt a bit. So I decided to ride my MTB which has DK Iron Cross BMX pedals. Man, what a difference. No pain at all.