If you suffer pain or sensitivity in both or one of your knees that does not stop after a short period, you may be suffering from chronic knee pain. Chronic knee pain may not be traceable to one single incident; some of the most common causes include tendinitis, a torn ligament, arthritis, a tumor, or a Baker's cyst. It's possible for chronic knee pain to interfere with your quality of life, making it difficult for you to enjoy the activities you love.