I have a tracking problem with my right knee and both knees are sucumbing to time and gravity. I have been through physical therapy for the right knee but I am not sure how much that it did help. I practice both Aikido and Iaido, so knee work is pretty much a given.
I have found a healthy regimen of vitamen "I"
and a really good product called "Biofreeze"
will get me through the more trying days.
If you have not tried Biofreeze I do recommend it. So far I can only find it at the local drug store. It does not take a perscription and they just order it (usually only takes a day) costs about $12 a tube.
It is pretty powerful stuff from my understanding, you could actually use to warm up with rather than stretching, not that I am recommending that!