Patellofemoral joint pain is the most common knee problem in active adults and adolescents. The pain is often located in the anterior and medial, anterior and lateral, or posterior aspects of the patella. It usually occurs during downhill exercise, and pain may persist even without running (especially when descending stairs). The patellofemoral joint is composed of the patella and the trochlear articular surface of the femur, and its stabilizing structures include the longitudinal quadriceps tendon, patellar ligament, and lateral vastus medialis, lateral and medial retinacula, and iliotibial band; the patella and the trochlear articular surface of the femur are屈膝20 βαθμός, η επαφή ξεκινά, καθώς η γωνία κάμψης του γονάτου αυξάνεται, η επιφάνεια επαφής μεταξύ του τυββίτη και του οστού του μηρού αυξάνεται, και η πίεση μεταξύ της γόνου-κνημής αυξάνεται κατά την κάμψη του γονάτου60 βαθμός—90 βαθμός, το μέγιστο επίπεδο, η κάμψη του γονάτου ξεπερνάει90 βαθμός, η τεντομηκής μυϊκή αλυσίδα του τετρακέφαλου μυός επαφάζει με το οστούς του μηρού, μειώνοντας την πίεση της γόνου-κνημής.
Causes that can cause patellofemoral joint pain include: congenital high patella syndrome, patellar cartilage fibrosis, tightness of the hamstrings, tightness of the Achilles tendon, lateral quadriceps muscle, tightness of the patellar bundle and lateral retinaculum, atrophy of the medial quadriceps muscle, and Q angle (>)15°.When the lower leg is internally rotated, the medial vastus muscle pulls the patella inward, while the other three muscles pull outward. The most common cause is the outward pull of the patella after excessive internal rotation, which撞击 the lateral condyle of the femur.