I've had success with a 10-day course of 100 mg of Fluconazole (Difulcan). The secret is to be sure to take it for a long enough period of time. The first time I took it, the strengh was 150 mg for seven days. The yeast came back on me with a vengeance. After taking Nystatin for a month, my doctor put me on 100 mg of Fluconazole for 10-days. This is my fifth day off of it, and so far, everything is going well. At first I felt very negative about Fluconazole because the yeast came back on me the first time I went off of it, but now I think it really works. I think 800 mg is way too much, though, unless maybe you are someone in the hospital with AIDS dying of a fungal infection. Fluconazole is very hard on the liver, so the lowest amount you can use to accomplish what you need to is best.
I'm curious, though. Did your doctor suggest a knee replacement as opposed to meniscus repair? That's usually what doctors suggest in instances like yours.