Hi Bonnie----sorry I did not get back til now to answer your question! It has been a week of trying to get my boys set for college, finding apartments, etc. so I have not been on bonesmart.
My original knee injury happened when I was thirteen. I was riding my bike and the bike hit sand. This was back in the days when traffic was not what it is now! The bike skidded out and I tried to break the fall but when my foot hit the ground my knee twisted badly and I could feel a pop. I was down on the ground and could not get up. A nice couple stopped to help me but when they lifted me to my feet the pain was so excrucuating that I passed out. And I was a tomboy, always active and pretty tough and pain tolerant! At the hospital I was told it was a cartilage injury and they did something they would never do now, they immobilized the leg in a full leg cast for six months. I did all the therapy but afterwards it remained unreliable and it was injured again when I was 17. I did not get the knee replacement til I was 57 but two orthopedists told me in the last couple of years that looking at my current x rays that whatever I did to the knee at 13 was "much much worse" that a cartilage injury. There was no ACL left at all, and I am thinking maybe it was a ligament injury.
I think in 1967 the imaging was not very good. My second ortho told me that even if they could have seen what the injury was, they would have had no way to fix it back then.
I give you so much credit for continuing to run and train even when you had the bad knee and you had to do it on your own and at your own pace. It takes tremendous strength and determination, both then and now, continuing to run and train after the TKR. I wish I had your drive and spirit.
If biking frightens you I think you might consider finding something that is fun for you. Biking is good because you can strengthen your legs and get a good workout but it is not the only way. I LOVE biking and to me it is tremendous fun, but I know what you mean about the drivers and cars frightening you. People drive with no consideration for the safety of bikers and pedestrians. I have a six mile route on a scenic road with a slow speed limit, but even that is narrow and full of sharp turns. I do sometimes ride off road but that has other issues. But still, I do love to bike and if I didn't I'd consider other alternatives.
I would LOVE the hot yoga, since I love yoga (something I am getting back to now that my knee isn't popping out of joint with every move) and I LOVE the sauna. I am a huge fan of regular sauna but have never tried the hot yoga. Let me know how you like it if you do try it.