What does patella tracking disorder mean? especially when there is pain?

Patella tracking: The knee cap or patella glides in a groove. If there is pull greater on one side of the patella vs. The other, the patella may tilt, sublux, or dislocate out of the groove. This problem can often be treated with physical therapy and/or bracing, but occasionally may require surgery.

Knee cap moves wrong: Your patella(knee cap) is not moving across your knee properly causing abnormal pressure and pain.