The exact cause of this syndrome is unknown, it is thought that narrowing of the ischiofemoral space is the inciting factor, leading to edema/tears in the quadratus femoris muscle - an external rotator of the hip.

An ischiofemoral (IF) space measurement of <17 mm is said to be suggestive of this syndrome. In one study by Torriani et al, cases had a mean IF space measurement of 13 mm vs 23 mm in controls.