MRI is commonly used for individuals who have low back pain with radiating leg pain to determine if a lumbar disc herniation causing nerve root compression is present. However, even though considered a gold standard by some, MRIs have a high false positive rate, which could lead to unnecessary treatment.
In clinical practice, the straight leg raise (SLR) is a physical examination test that is commonly utilized and has been shown to have high sensitivity, but low specificity, for the detection of a lumbar disc herniation. This generally means we can use the SLR to “rule out” a lumbar disc herniation (via a negative SLR) but not to “rule in” this condition. Previous research has attempted to modify the traditional SLR to increase its diagnostic properties by adding a structural differentiation movement of hip internal rotation or ankle dorsi flexion, termed the extended SLR.
Extended SLR procedure and interpretation:
For the extended SLR maneuver, the patient lies supine on the examination table with the examiner passively lifting the subjects’ leg with their knee fully extended, hip in neutral rotation and ankle hanging freely. The leg is raised until the first symptoms appear or the subject’s ongoing symptoms in their lower extremity are aggravated by 30%. If the leg reaches hip flexion of 90 degrees with no response in their leg, the test is considered negative.
If the subject has a lower limb response, in order to determine if the response was due to neural or MSK origin, a location specific structural differentiation movement is added, which is selected based on the location of the symptoms. If symptoms are located distally below the knee, hip internal rotation is performed at the same degree of hip flexion of the evoked response, and for symptoms provoked proximally in the buttock and/or hamstring area, ankle dorsiflexion is performed, which was similar to the Braggards test. The extended SLR is considered positive if the differentiating movement increases the subject’s evoked symptoms.
The extended SLR is different from the traditional SLR in three ways:
- The evoked response does not need to reach below the knee
- The lower limb response does not need to emerge before 70 degrees but can happen anywhere from 0 to 90 degrees of hip flexion
- There is a structural differentiation maneuver added to the traditional SLR test
Previously, the extended SLR has demonstrated perfect interrater reliability between examiners in detecting sciatica patients (5). This current study aims to investigate whether the extended SLR is associated with pathological findings on MRI, in order to determine its usefulness for clinical decision making.
THIS WEEK'S RESEARCH REVIEW: “Validity of the Extended Straight Leg Raise Test”
This paper was published in BMC Musculoskeletal Disorders (2021) and this Review is posted in Recent Reviews, Low Back Pain, Lumbar Spine - Disc & Neurological, Clinical Testing & Procedures and the 2022 Archive.