I basically destroyed my right leg a year and a half ago and had knee surgery along with fractures in all 3 leg bones. Also while learning to walk properly again I managed to strain my left knee. Long story short I am now working out and doing fine with both my knees. During my leg workouts which admittedly have been light and careful I have started doing hack squats and upping my weight. For the first time I really feel no resistance in my knee. Would it be a good idea to start doing squats on say a smith machine in order to feel my body out or is this the type of injury that I should just avoid squats all together?