My wife has had one knee, both hips replaced and both SI Joints fused in her lower back. Also two cervical spine fusions and had an artificial disc implant. She can walk, but not far and relies on a cane some time. She can’t kneel down and it is difficult for her to get up out of a chair. She is 55.True - and hips. However, modern day medicine and we get do overs Although they do not like to do them at younger age. I just had my hip done and I have to so I'm glad I did. I couldn't wait any longer so we had no choice. 7 months in a year long recovery before 100% complete but was walking less than 12 hours after it was done. Really amazing.