The Science: What do we know?
What is the IT band?
The IT band (iliotibial band) is a thick fibrous strip of connective tissue that runs along the outside of the thigh. Connective tissues, known as fascia, are similar to tendons and ligaments. The IT band is anchored at the iliac crest of the pelvis and down at the tibia shin bone just below the outside of the knee. Thus ilio + tibial gives the the name iliotibial band. The IT band is also affixed to the thigh muscles along the leg so the IT band does not move freely under the skin. The IT band stabilizes the knee during running and keeps the knee from bending outward. The buttock muscles and the hip joint muscles engage and tighten the IT band to help control the leg and knee movement. The IT band is extremely tough and strong.
What is IT Band Syndrome?
IT Band Syndrome (ITBS) is an injury most commonly caused by overuse in distance running as well as biking, hiking and other repetitive activities. The injury causes pain that is concentrated at the outer side of the knee and is described as a stinging or sharp stabbing pain that can make running unbearable even after just a short distance. The pain may extend above the knee along the IT band going up and along the outside of the leg.
The pain is a result of irritation where the IT band passes along the outer side of the knee. There is a small bony protrusion called the femoral epicondyle on the outer side of the femur bone. You can feel with your hand this bony protrusion most easily when standing.
The IT band has some movement across the femur and the bony protrusion. This movement is often describes as a sliding action but can become more of a friction, or over compression, when things go wrong. The IT band is narrower and so less strong near the knee so this area may be more prone to strain and injury. The complex movement (pulling and bending at once) of the IT band at the knee may also make it more prone to injury.
Inflammation under the IT band may occur at the site of the femoral epicondyle. Some experts describe a lubricating sac, called a bursa, between the IT band and the knee. The bursa may be the site of the irritation.
Is IT Band Syndrome fully understood?
We know a lot about IT Band syndrome but there are still many things that are not understood fully. We know for sure that the IT band is involved in this outer knee irritation. We know that IT band is controlled by the tensor fasciae latae (TFL) as well as the gluteus muscles. We know that knee bending is involved. We know that a larger knee bend (known as flexion angle) causes more strain and therefore may result in more irritation and pain. Excessive repetition may lead to irritation and pain.
We believe that more muscle strength and more flexibility is good. Increasing the strength and flexibility of muscles and tissue that control the IT band is therefore believed to help.
How Common is IT Band Syndrome?
Iliotibial Band Syndrome (ITBS) is one of the most common overuse injuries among runners.