When you get around to doing squats again... Several professionals have told me to avoid bending a problem knee beyond 90 degrees. But I have been doing lots of squats - one-legged (with a ball against a wall) and two-legged - and staying > 90 degrees. The key is to concentrate on using hamstrings and glutes to get yourself up - with less reliance on quads, and no reliance on momentum. For anyone with kneecap problems (which may not apply to you), wide-stance squats are supposed to be avoided because the kneecap is pushed laterally. I had been doing all kinds of them, because I wanted to strengthen my adductors. Oops.