It is an overuse injury from repetitive overloading of the extensor mechanism of the knee. The microtears exceed the body's healing mechanism unless the activity is stopped. Among the risk factors for<unk>  are low ankle dorsiflexion, weak gluteal muscles, and muscle tightness, particularly in the calves, quadriceps muscle, and hamstrings. It may be associated with stiff ankle movement and ankle sprains.
Patellar tendinitis
Osgood–Schlatter disease
Pes anserine bursitis
Chondromalacia patellae
Prepatellar bursitis
Patellofemoral pain syndrome
Infrapatellar bursitis
Ischial bursitis