Hannibal said:
Try placing the bar out in front of you more...so you are pulling the bar back. It allows you to use your bodyweight for more leverage (see-saw). Also allows you to pull in a straight line instead of out and around your knees.
I would suggest the exact oposite of what you said. I have a feeling the banged up knees is from pulling weight that is too far away; the weight ends swinging into your shins/knees. Now if you place the weight close to you it'll come up strait and won't touch your legs...
My 2 cents,
Ingram