The iliotibial tract or iliotibial band is a longitudinal fibrous reinforcement of the fascia lata. The action of the ITB and its associated muscles is to flex, abduct, and medially rotate the hip. In addition, the ITB contributes to lateral knee stabilization. During knee extension the ITB moves anterior, while knee flexion moves the ITB posterior. It is attached to the anterolateral iliac tubercle portion of the external lip of the iliac crest and to the lateral condyle of the tibia.