Biomechanical considerations in the straight-leg-raising test. Cadaveric and clinical studies of the effects of medial hip rotation.

Studies of the sacral plexus have been made in six cadavers to demonstrate the increased tension due to medial hip rotation. A standard protocol was adopted for the straight-leg-raising test (SLR) and three qualifying tests--dorsiflexion of the ankle, medial hip rotation, and cervical flexion--when examining 442 patients. Positive signs on medial hip rotation were frequently associated with evidence of increased tension and neurologic dysfunction of lumbosacral roots. It is concluded that uncontrolled hip rotation reduces the value of the SLR is a useful qualifying test for increased root tension, and that the diagnostic value and repeatability of SLR would be improved by adopting a standardized protocol.