I have Osgood Schlatter's; to the best of my knowledge there is no outward sign of patellar tendonitis. However, Osgood Schlatter's does have a sign. About an inch below my knee cap it looks like I have a marble under my skin. There is a HUGE bump. It makes kneeling a nightmare to this day. I technically had it in both knees but my right knee marble is huge! My left knee, it's more like a tic-tac.