X17 has just discovered that Britney visited a surgeon a few days ago to discuss another operation on her busted knee. Considering that her last knee injury brought an end to her tour (and enabled her to spend more time with then-boyfriend Kevin Federline), let's hope it's not necessary - and if it is, that she'll pick a more suitable back-up dancer to help "nurse" her back to health!

Click through to see how the knee injury started it all: