The straight leg raising test: its relevance to possible disc pathology.

The records of 40 patients who had suffered from low back pain, and who had a marked restriction of straight leg raising (SLR) have been studied. Thirty-four of these cases had referred pain down the lower limb. They were all treated, at least in the first place, by manipulation. The response to manipulation demonstrates that, in the absence of evidence of interference with nerve root conduction, limitation of SLR is an unreliable sign of possible disc pathology. Furthermore, the immediate response to manipulation, particularly in the known disc protrusions, strongly suggests that muscle spasm plays a major role in limiting SLR. These points are discussed.