@ dwing
IMO, everyone is different and for injuries well you can only do what you can do really, there's going to be limitations with a pulled/torn ligament and fractured bone, slipped discs, etc...
I do agree with the knees being too forward is not the way to go with squats. I've always pictured it as picking up a can of soup with your ***?
I know it sounds funny but it does provide the best form. That might be too low for some, again it depends on the person, if you feel comfortable going that low then go ahead. That being said you have to squat down far enough to make a difference, I'm not talking about these guys that put 500lbs on there and not engage their hip flexors. I also pick a spot high up on the wall (@ Gold's it's right above the mirrors) that I look at while squating, therefore it negates you from rolling your back and creates a linear line/slat of your back while doing squats and deadlifts. I've always believed moreso on how it feels on my body than a broscience saying that it MUST be 90 degrees otherwise its no good. We all have different strengths in our hamstrings, quads, calves, etc... its our job to find those weaknesses and improve them is always my way of thinking.
I'm a naturally bodybuilder and in no way shape or form do I plan to compete in strong man competitions but I've work so hard on form and doing the right exercises correctly that I'm probably one of the most powerfully natural bodybuilders in Missouri for the amount of weight I push for my frame, size and bodyfat percentage. It all takes time, 35 years in the making, can't wait to see what I look like at 50.
Ski