I have arthritic knees, so these flip flops were actually great in dealing with that.  I can wear them all day long and not experience the same pain I do with regular flip flops.  The only problem is that even after a few wears, they kept rubbing the skin on the top of my foot the wrong way, sometimes resulting in blisters.  Not really sure what to do about it, but I'm willing to invest a little bit more time next summer in trying to figure out a solution for this because they are that comfortable.