Sources of anterior knee pain.

The anterior part of the knee consists mainly of structures belonging to the patellofemoral joint, which includes a variety of tissues, such as cartilage, subchondral bone, synovial plicae, infrapatellar fat pad, retinacula, capsule, and tendons. Each of these structures, alone or in combination, can be a source of anterior knee pain. Unphysiologic load or changed metabolic activities can lead to structural failure with loss of homeostatic conditions.