not knee but ankle replacement but one thing correlates - choose your surgeon carefully. when I had my surgery eight years ago ankle replacement was still considered experimental in this country and needed advance approval by the feds in order to be covered by insurance. that took almost a year while I limped around with a cane. my local orthopod referred me to a guy at duke who had already done dozens in Europe and was considered one of the best in the world. one of those guys where every time he comes to your hospital room postop there's an entourage of about a dozen minions following him around. my point is I know a handful of others who have had the surgery since and most have had problems, while mine continues to serve me flawlessly and pain free. I also know others with hip and knee replacements and the results seem to be similar - heavily dependent on the surgeon. do your research and get more than one opinion. who does it could make all the difference.