As one who has been there, done that, (I've had major meniscus tears and surgeries in both knees) I would opt for the surgery. The surgeon will do everything possible to minimize risks, and they have to warn you of them. I also have some coronary issues, so I know those risks also.

After surgery, you will have lot's of physical therapy, which will strenthen the knee. I had a partial knee replacement just over a year ago, and I am very glad I had it done. My knees were so bad that I had to give up canoe trips after 07. This past summer, I was able to resume tripping.

While it is never pleasant to consider surgery, I believe that if you do it, it will add years to your outdoor life.