Hi Irene,
I am sorry that you are having this problem! My initial TKR was in 2008 with a revision Mar 29, 2011 at Mayo. The patellar clunk was diagnosed by the surgeon who did my revision the end of June, 2012 So, it occurred more than a year after my revision. Arthroscopic surgery was delayed until July 13, 2012 because the sports medicine doctor (Dr Dahm) was traveling with one of Minnesota's professional sports teams. As soon as she got back into town, the arthroscopic surgery was done. I had very little pain before the procedure and not a lot after. I did not have testing of any kind. I just had difficulty extending my knee and it made an awful noise when I did (a loud slurping sound). The surgeon who did my revision TKR was sure that it was patellar clunk. The arthroscopic surgery Dr Dahm (sports medicine) did confirmed the diagnosis. The pictures Dr Dahm took were amazing. I did get immediate results (other than some pain and stiffness) and did not have to have PT. I was told that there was a good chance that the tissue would grow back but it never did. I have since had a TKR on my other knee (and later a revision) but have not developed patellar clunk in that knee. Hope this helps!