I had arthroscopic surgery on a torn meniscus and was given a 10% PPD rating. Since that time I have had three surgeries, one for a partial knee replacement (which did not work), one for exploratory to see why it did not work and a total knee replacement. I was doing well, post surgery after 5 months my doctor gave me a 10% PPD rating which is the same before I went through 3 surgeries. I have been taken off my celebrex and now my knee swells, I have trouble walking stairs and getting up from a sitting position. I have a return visit to my doc -- how are ratings determined. Are there guidelines?