You can always consult an attorney. I would obtain copies of all your medical records pertaining to your knee and review them. It is very difficult to claim malpractice. You must prove your current outcome would have been different before the care. A friend of mine tore his quad muscle after his second knee replacement. Put the cast on over a small opening with drainage and never tested that drainage. To shorten this year-long story, after multiple surgeries, the Dr. not removing his prosthetic when there was an active infection and saying "I thought it would be OK left in", multiple debridements and ultimately an amputation, he still is fighting his case. Now, if he pursued it he would lose his disability for his seizure disorder and all insurances associated with it because his income bracket would be too high. How is that fair? What is your bend? My ortho says 90 degrees is what they want for success and anything higher is a bonus. The release you sign before surgery saying you understand any and all risks makes them safe from malpractice.

@damewocane As @bonzobear72 said, it is very hard to sue for malpractice. The doctor really has to be proven negligent, and generally, they want other doctors to testify against the doctor being sued, and often doctors stick together, except in rare cases when the doctor being sued has really botched things a lot. That happened here with a woman ob/gyn doctor. She is no longer allowed to practice that specialty but can practice general medicine. Actually I don't think she was being sued by a patient but the other doctors pushed to get her out of the department and succeeded.
JK