OK, ScurvyDog: I am rehabbing a freakin' broken back in five places, and I am managing to move my body! So no excuses now, ya' hear?
Big ups for any sort of water classes. I do my running-for-my-life sprints in the pool.
You can do planks and side bridges with a bum knee, so get to it. You use your knee to do pull-ups, push-ups?
You can work your back, arms, core, etc. You're not exactly in a full-body cast, so no excuses.
C'mon, man, there's even Sit and Be Fit on PBS!
(Yes, I'm pushing you here!)
Also, the longer you are Primal, the better your joints will feel as you will no longer be inflamed and stiff. Make up some bone broth from marrow bones every weekend; this will help. And take your fish oil regularly.
Find a good physical therapist, and come back better, stronger than before.
Best wishes on your recovery. I'll be checking back to see your progress. You are a survivor, not a victim.
"Let food be thy medicine and medicine be thy food." -- Hippocrates