I have had both of my knees replaced in 2003. I had them done about 10 months apart. When your mobility becomes limited and the pain is too much you will get them done. I got to the point where I could walk for limited amounts of time and then had to sit down because of the pain. What really got me was a fall in my office. My quadriceps completely let go and I was on the floor. That happened twice and I knew that my ever weakening quads and hips were the problem. The problem is the constant pain will inhibit your muscular system to the point of failure. You can try to strengthen your legs but the pain will win everytime. I have never seen anyone who could work through the joint pain in a knee with severe osteoarthritis and perform well. I am a physical therapist and I see lots of total joint replacments. I have been practicing for 43 years and feel that when the time comes you will know when to get them done. Most people wait to long to get fixed, I know I did. Hope this helps.