How hard you would kick your opponent, there wouldn't be any damage, but a nicely placed hit could dismember your opponent because of it displacing the joints.
That kind of relates to real life fighting.
If you kick someone really hard in the thigh, I'm sure it would hurt them but they would recover quite fast.
If you kick them really hard on top of the knee, then there's a likely chance you would do more damage than the thigh kick.
Ok, sounds good, but in some of my madmans i have smashed peices together and the tension on uke's joints was enough to dismember anyway, thanks though.