While running a few years ago-- around 30,000 miles total--I felt pain in my left knee. After putting up with it for several days, I went to the orthodoc. It was a torn meniscus. He fixed it. About a year later, the same thing happened in the right knee. More surgery/fix. Both surgeries were outpatient. I had pain during the first three or four nights after the surgeries; I got up, walked a few steps and went back to bed. I don't recall exactly how long it took to get back to normal walk > little jog > run; but it not more than a few weeks before I felt back to normal. I ran several thousand miles after the surgeries. This morning, I walked three miles and ran one. (I am a very young 79.) Check with your orthodoc to get your options.