Firstly, I think this is slightly beyond any of our actual knowledge base as a physician should be consulted.
However, if I had to give some advice for training, I would say back off of the weight and boost your reps. Focus on doing lifts with perfect form.
I would stay away from squats, and move to a leg press machine and only do quarter or half way on those. Make sure that your feet stay out in front of your knees, and that your knees (when performing the exercise) never extend out past your feet.
Then I would do standard leg extensions, leg curls and calf raises. Again, lower your weight, and up your reps. Also, I would work each leg individually instead of together. This will allow you to really focus on your form.
I'm not sure what sort of cardio you do, but, supplement some of it with incline walking. It's less impactful on your joints, is a great leg workout, and is quite healthy.