Thanks. But its not so much a modelling problem as a bones setup problem. Or so I think.
Is there no way you can prevent the knee from folding backwards by using a constraint of sorts on the skeleton itself. I have seen this done in animation:master and poser, but the systems they use would not work in this instance as Blender has only 4 constraint types, or am I missing something…?
I had limited success by using an empty placed just behind the knee joint and then placed a constraint on the shin bone (not sure what the medical term for this bone is ) to track to the empty. It works great but when the armature moves the empty stays put. So then try to parent it to the bone or armature, blender crashes. Do the parenting first and then place the constraint and the constraint no longer prevents the knee from folding back…