Iliotibial Band Syndrome (ITBS) is one of the most common overuse injuries among runners. It occurs when the iliotibial band, the ligament that runs down the outside of the thigh from the hip to the shin, is tight or inflamed. The IT band attaches to the knee and helps stabilize and move the joint. When the IT band isn’t working properly, movement of the knee (and, therefore, running) becomes painful. IT band pain can be severe enough to completely sideline a runner for weeks, or even longer
Because the most notable symptom is typically swelling and pain on the outside of the knee, many runners mistakenly think they have a knee injury. The best way to tell if you have ITBS is to bend your knee at a 45-degree angle. If you have an IT band problem, you’ll feel pain on the outside of the knee.
Additionally, sometimes an MRI can confirm whether your injury can be diagnosed as ITBS. An X-ray will usually produce negative results, but an MRI can show a partial thickening of the band, which results from inflammation.