The doc diagnosed it as Patello-Femoral Syndrome. It may or may not have been related to the degeneration caused by Stickler Syndrome, but she seemed to think it was not. What it is is when the patella (or kneecap) doesn't slide smoothly in the groove of the thigh bone. The patella is held over the thigh bone by tendons. Damage to the tendons or muscles could be the cause. I think that mine has to do with muscle weakness as I haven't been walking as much as I used to. I also sit cross-legged a lot, and I think I overextend the tendons. That is just my theory.
Patello-femoral syndrome is more common in people with knock-knees, and in women because our hips are wider, thus our knees tend to bend inward. Me, being a knock-knee'd woman, is a double whammy. ;-)
Anyway, the doc prescribed a neoprene knee brace (I just got one to try it out first), these neat silicone wedges to put in my shoes - they are called M-Pact Multi-pads with Posting Orthotics, and physical therapy.
Here is a pic of my xray (not bad for a camera phone, eh? A little fuzzy from the hand shake but not too bad.) Notice how my knee caps are way over to the side:
Here are some useful links:
Health Encylopedia at USA Today
Description of Patello-Femoral Syndrome at Rice.edu
Entry at MedicineNet.com
It is possible to also repair PFS through surgery, if physical therapy and orthotics do not help. I think I'm far from needing surgery, but good to know the option is there. Here is a site that explains the procedure:
Knee Arthroscopic Surgery
