I am having a left knee revision on a one year old TKR on Feb. 12. My knee has been unstable, and progressively more painful. I can only stand or walk less than 5 minutes before I need to sit down and rest my knee. The doctor says it's just a polyurethane replacement, but I am afraid it is something much worse. No one knows for sure until he can see what is going on inside. I just really need support right now, and I am glad I found this forum before my surgery.