Stick leg wrote:
I have this problem too. I have had a string of consecutive injuries always in my left leg (IT band, hamstring syndrome, runners knee, soleus pain, etc....). I believe my left leg has been smaller/weaker before these injuries but now my it is significantly smaller than the right. Unfortunately, the way to reverse the atrophy is to strength train but that also aggravates the injuries that weakness caused in the first place. It seems like a cycle that's impossible to escape. Let me know if you find out how to strengthen with a knee injury.
First of all, if you are chronically injured, you need to seriously consider finding another sport.
However, to answer your question--very often, it is possible to strengthen the quads without causing additional damage or pain to an injured knee. What you must do, in such a situation, is figure out which exercises, or ranges of motion, do not stress the injured area. For example, when I had an articular cartilage defect in my right medial trochlea, I could not do leg extensions or squats, but I could do limited range-of-motion leg presses.
In general, when dealing with a strength discrepancy, it is helpful to train unilaterally, and to perform no more reps/use no more weight with the stronger limb than you can with the weaker limb.