Originally Posted by bluegreyhound

Torque at the knee is apparently maximised when the angle at the knee joint is 90 degrees. Put differently, for a given weight on the bar, your knees are stressed the most when your squat stops at the "parallel" point. Therefore, to minimise stress levels at the knee joint you could stop at slightly above parallel or at some point below parallel. I have small bones and measure about 14 inches around my knee: I have no problem squatting heavier weights and keeping my knees healthy. You are more at risk in my opinion when doing plyos incorrectly.

BTW if you adopt a wide foot stance you definitely should think about sitting back when descending and not down. However, if you use a narrow foot stance you can't really sit back in the same way due to the need to keep your centre of mass over your feet. That said, most people put their feet slighter wider than should width. If you box squat, you'll tend to use a wider stance too.