The iliotibial (IT) band is a thick band of connective tissue that runs along the outside of the knee and up to the outside of the hip. It helps move the hip through extension, lateral rotation, and abduction. It further helps stabilize the knee joint.
However, sports or activities that require constant bending of the knee - such as running - place stress on the IT band, near the knee. When the IT band becomes tight or aggravated at the knee, pain or swelling may arise. This results in a condition called iliotibial (IT) band syndrome - also known as “Runners Knee.”