"Patello-Femoral Syndrome - a condition caused by the patella not tracking properly. The patella normally rides in a groove on the femur. The patella is really a fulcrum - it gives leverage to the quadriceps. The quads are so named because they consist of four muscles. With PFS, you get an imbalance in these muscles - usually the lateral or outside muscle over-powers the inner medial muscle - and this pulls the patella out of it's normal groove. When the patella doesn't track properly in it's groove, it causes pain under the patella."
* Physical therapy to balance the quad muscles and realign knee tracking.
* Cortisone injections.
It's okay to run as long as it doesn't hurt. Don't be surprised if pain returns with running because the underlying condition is still present until treatment is completed.