You didn't. That's the most self-destructive thing I've ever heard. Who's your orthopedic surgeon? If you don't have one now you should start looking. Just come to Osaka and I'll bash you in the knees with a hammer and at least one of us will get some entertainment that way. As for the large boulders thing, that's silly. What constitutes a "large boulder?" What martial art and what country? How strong do you suppose these people were?