Here's
the article.
"The knees will naturally bend (slightly that is) as you descend and the shins should remain vertical. Make sure to keep the bar close to the body (even dragging along the thighs)3 and the back flat, which will minimize the risk of injury.8
Keep the arms straight throughout the movement. If you're doing it right, you'll feel it in your hamstrings.
For most people, the bar will just cross the knees before the back loses form. At this point, it's time to reverse the movement and come back up. Don't allow the back to round and don't hyperextend the spine at the top of the movement. In other words, stand tall at the top, but don't lean backwards.2,10,17,20"
I've not had a reason to doubt the articles over at T-Nation. So, who's correct? Personally, I think it makes more sense to bend the knees as little as possible, thus keeping the hips out of the exercise whos primary target is the posterior chain. Is that incorrect?