iliotibial band syndrome
noun
variants:
also iliotibial band friction syndrome \ -ˈfrik-shən- 
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Medical Definition of iliotibial band syndrome
: a sports injury that is marked by diffuse pain in the lateral part of the knee and results from inflammation of the iliotibial band due to overuse (as in long-distance running) as it slides across the lateral condyle of the femur as the knee is flexed and extended repeatedly
About 15 miles into the race, he experienced iliotibial band syndrome, an injury common to runners that produced pain mainly on the side of his knee.— Solomon Crenshaw Jr., The Birmingham (Alabama) News, 5 Nov. 2008