TweetBrother, I have bad knees and a bad back. I squat high reps, slow and controlled with light weights. Got to leave the ego at the door for me. 135# is all I will do or the axial load on my back leaves me hurting for 7-10 days. Leg extensions and curls same. Low weight high reps to protect knees. Sucks, my days of squatting 8 plates are LONG gone. Hell I bet I would fold up under 225# now as jacked as my back/knees are.
Do what you can without too much pain so you can do it again. I feel volume with light weight is good. In the past I used to only use an oral on leg days. 25 mg of winny or pretty much any oral just to give you a better pump and extra anabolism to help your legs catch up.