How can i tell if i have patellar tendonitis (jumpers knee)?

Tenderness: The area just below your knee cap to the bony protrusion of your upper tibia (about 6 cm in length) is the patellar tendon. If it is tender to touch or painful when you squat or extend your knee, you may have patellar tendonitis. This condition is sometimes very resistent to treatment. If you experience pain there for a prologed period of time, i suggest that you see your doctor.