Cynthia used to be a top ninja, but she got into a situation where she couldn't escape against then Emperor Danny and injured her back and knee and would of killed her if Cuddlina didn't distract him from her, but her decision to attack Emperor Danny (even in the case of saving Cynthia) caused Maria to fire her for negligence.
Due to her being a ninja and Star Fleet still huge in the government, she was rejected for disability despite no longer being one. So the back brace, knee brace, and cane were from the garbage and it's hard for her to do anything without the help she cannot get.