Since the summer of 2011, I have been bothered by stiffness in my left knee. I could tolerate the pain but finally this fall the swelling in my knee became obvious and I had an MRI done in October. It showed that I have moderate chondromalacia ... and subchondral edema. This translates to a bone bruise. I stopping running and switched from playing a lot of tennis singles to doubles. It still wasn't getting better so I stopped all tennis and began swimming for the last 5 weeks. Swelling is almost all gone and no pain but some stiffness remains. How will I know when it is OK to go back to playing tennis doubles? Also, if I play with some pain, does this mean that I am doing more damage.