I will be 80 next month. Had right knee surgery some years ago and excessive walking on that knee will stop me. A cane doesn't help at that point, too much pain to continue so I understand your problem. I'll be in my house and kill anyone trying to get in. I have secured the house, windows and doors (doors can't be kicked open). I'll hear alarms going off if windows or doors are touched enough to cause the vibration detectors to go off.
I can buy more ammo if I want and probably should. Too bad you gave up the artificial nails. I was always afraid those would set up an infection as some did, but my fingernails were, and are, long enough for me as I have to file them to shorten them so I don't look like Dracula.
Thanks for your post.