It's been 3 yrs since my TKR and I've had conversations with many TKR patients and what I've learned is that everyone has a different experience with recovery results. Like you I'm just now 80 and walking up or down stairs was a big challenge before surgery and still even after a year of doing all of the rehab exercises, so I told myself "I guess this is how it's going to be for the rest of my life". About a year ago I noticed that I had put on about 10 pounds and decided that I'd get back into shape and added some exercises and the old walking routine to loose some of the pounds. Months later I'm doing more wood working, more yard and garden work, etc and the weight was down most of the way. One thing I hadn't given up on was walking down stairs like normal people and would test to see if the knee would work from time to time. Late last year after an all day session in the garden I happened to do one of those stair tests and "Hey I just walked down about 4 steps the normal way." Since that day I've found that when I don't exercise the knee I'm not as successful at stair climbing as I am using the knee a lot. My thought is don't give up trying and keep exercising, it's a good thing!