@cyndi2013

The bell curve rule operates on TKRs as well:

No matter how good the surgery, bad things can happen. My research was designed to maximize the probability of a good outcome but one can't guarantee it. An implant can wear out, the patella can separate, the spacer can separate, etc.

IMO an excellent physician anticipates the worst as well as the best and plans around it. But go ahead and find someone who thinks that all his surgeries come out perfectly. I don't want that delusional surgeon.