Knee surgery caused more damage. Is this medical malpractice?

The answer to your question depends on a number of factors. For example, what type of surgery was it and did the doctor warn you beforehand that your knee might be worse after the operation? If so, giving informed consent could mean that you are not entitled to file a lawsuit. If not, even if the doctor performed the surgery competently, failure to warn you of the potential dangers could be medical malpractice. However, the most important factor is, why is your knee worse. If your knee is worse simply as a result of the surgery itself, and you knew of that risk, you probably can’t sue.  If, however, your knee is worse because your doctor made an error or mistake in the surgery, that could constitute medical malpractice.  You should speak with an experienced medical malpractice attorney about your situation to get more advice on how to proceed and whether your doctor’s behavior rises to the level of malpractice.