Several ladies in my water aerobics class have had their knees done. The Rehab is the most important thing to do. And several of them said their doctors told them that exercising in the water is the best thing for them. I know I will need it one day in my future and having seen these ladies work it out, I am not afraid at all! Good luck!
(One lady had both knees done at one time - she said it was the best way to have it done.)