My health was at risk pre-TKR. My activity level was really compromised and I had been pretty active before the last two years when things went bad quickly. Once, about 4 months ago when I was going downstairs, my knee gave out 4 steps from the bottom and I flew forward. My hand hit the glass side window by the front door when I came to a stop. Glass didn't break but I was scared for sure. My OS asked me if I could walk a city block without pain before agreeing to surgery. I couldn't take a step without pain!