The Straight Leg Raise Test: How We Keep It Straight

The Straight Leg Raise (SLR), a test often used to tension the sciatic nerve, is well known for its ability to rule in or rule out lumbar nerve root pathology (radiculopathy) that may be manifesting along the sciatic nerve trajectory. This often presents as leg pain, numbness, and/or tingling of the lower extremity.

To perform a SLR, with the patient supine, the examiner raises the leg into passive hip flexion while maintaining the knee in extension.

So how is a negative or positive SLR test defined? The criteria can vary from source to source. Some literature states that the absence of leg pain and/or paresthesia constitutes a negative test while the presence of the above would be a positive test. Other literature suggests that raising the leg into more than 70 degrees of hip flexion defines a negative test. The inability to reach 70 degrees of hip flexion in combination with lower extremity symptoms would define a positive test result. With variable criteria there is more room for interpretation which can affect overall test reliability. Simply stated, you and I may not come to the same conclusions when using this test on the same patient. This is known as inter-rater reliability.

Reproduction of symptoms along a dermatomal distribution has moderately good inter-rater reliability while leg pain does not (Vrooman, et al. 2000). A range of hip flexion below 70 degrees has not been universally agreed upon and can vary in patients that are hypermobile or who may be experiencing mild residual symptoms.

Several issues with SLR reliability have been identified. For example, posterior thigh discomfort from hamstring tension, is often misinterpreted as a positive SLR. A lack of standardization in testing position is another issue that commonly occurs. Performing a SLR with the head elevated on pillows, not locking out the knee, allowing the lower extremity to veer into slight abduction/adduction, and allowing the hip to medial/lateral rotate are some examples that can potentially skew your findings leading to false positives or negatives.