It sounds like many people have had some terrible experiences from their knee replacements. Before I had both my knees replaced five months ago I had researched a lot and learned that 30% of people are not happy with their new knees. To counter that research, I also hike with numerous people who have had very successful outcomes from their knee replacements.
I am very risk adverse so I had to examine whether I could cope with my increasing limitations in doing anything physical. Walking was painful after 10 minutes and I had bone on bone , synovitis, osteophytes,..
I think for me, the final straw was my legs became so bowed and it was very noticeable and hugely impacted my ability to walk comfortably.
I researched my Surgeon and he used the Mako Robotic System, glue for the incision line and prescribed OxyContin, Celebrex, and Tylenol.
For me, the risk was incredibly worth it and my Physio had mentioned no two knees are alike. I had my knee replacements done two weeks apart and did find I had less stiffness with my right knee versus my left knee.
I do empathize with those who had a poor outcome and hope there is some solution in the future to improve their quality of life and mobility.
I continue to increase my walking and hiking with no pain but stiffness at night if I sit too long.