So it looks like I'll be opting for arthroscopic surgery on the knee. They'll "bleed" the knee above the "pothole," filling it with what-will-become fibrocartliage. While not as strong as organic cartilage, there's a chance it could close said pothole nicely, allowing me to race into my dotage. (Not far.)
There's physical therapy and months of EZ walking and light running. But by then, I should know if the pothole can withstand marathon pounding.
Ahh, well, there. No more moping about. A direction. A risk. Life. Procrastination. Just a little. I'll call 'em Monday and set it up.