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Definition
The iliotibial band (ITB) is a thick broad tendinous band which is the distal extension of the tensor fascia lata muscle of the pelvis. This muscle transitions into the ITB 1/3 of the way down the lateral thigh and it then travels accross the knee to the proximal tibia. The term iliotibial band syndrome refers specifically to pain in the lateral knee from a tight ITB rubbing over the lateral condyle of the femur. A tight ITB can also cause problems over the proximal thigh at the greater trochanter where increased pressure at the bursa can cause tenderness and pain.
The iliotibial band inserts onto Gerdy’s tuburcle of the lateral proximal tibia, but also has minor tendinous attachments to the patella and lateral femoral condyle.
The function or action of the iliotibial band and tensor fascia lata is to flex and abduct at the hip, as well as medially rotate. It is a significant structure of the lateral knee providing lateral stability. The iliotibial band moves forward in extension and backward in flexion but is tense in both positions.
Commonly used diagnostic procedures include physical exam and history. MRI is used more to rule out other pathology which can mimic iliotibial band syndrome. The ober test is perfomed by having the patient lay on his side with the iliotibial band to be tested facing up. The hip is then abducted and extended with the knee flexed, and it is then brought into adduction to see how tight the band is as it contacts the greater trochanter. Palpation of the greater trochanter is also a way to determone if the tight iliotibial band is causing irritation to the bursa. Distally, the condyle of the knee is palpated for tenderness and snapping of the ITB over the condyle.
It is usually treated with NSAIDs and physical therapy which focuses on stretching. Injections can be used in recalcitrant cases and rarely surgery to release the band if non-operative treatment fails.
References
http://www.wheelessonline.com/ortho/tensor_fascia_lata_iliotibial_band