In April of 1999, Mobius underwent an operation to fix her left kneecap, which wasn't staying where it should. (ouch!) Since she was so young, and it obviously was causing her pain, we decided to get it fixed. We figured that would make her good as new, and a much happier cat.
However, it became apparent that she wasn't good as new - her other knee also had problems. So, on January 5th of 2000, she went in for a second knee operation.