I had a bad injury to a knee 3 years ago when I was 73, had to have open surgery to repair everything that was torn. Didn't get a replacement but had to go through the same rehab as the replacement guys. Took months to recover, and it wasn't until 2 years after that I could actually hunt like before.
Best thing I did, once my PT was completed, was to get a treadmill, both for the walking and because they are a great place (when motor is off) to do knee-bends, because your arms are supported by the TM's arms, so if your knee gets weak you can catch yourself with your arms and immediately take all strain off the knee.
Now my knees are so strong I do 10 minutes of knee-bends 3 times a week. You gotta keep those leg muscles well developed or you're just asking for a bad injury while hunting.
