Significance of a persistent positive straight leg raising test after lumbar disc surgery

Results of the straight leg raising (SLR) test provide the clinician with valuable information regarding possible causes of a patient's pain. In a previous study the results have also demonstrated a correlation between the outcome of the test and the severity of pain, as well as the prognostic value of the test; patients for whom the SLR test is persistently positive postoperatively appear to have a poorer short-term outcome. In a prospective study of 200 consecutive patients who underwent surgery for disc herniation, the authors evaluated the frequency of repeated surgery and outcome of surgery in patients with a persistent postoperative positive SLR test.

The preoperative radiological evaluation included myelography, computerized tomography scanning, and/or magnetic resonance imaging. Preoperatively as well as 4, 12, and 24 months postoperatively, each patient was interviewed and examined using a standard protocol in which common symptoms and signs were described. The result of the SLR test was also classified into one of four categories: positive 0 to 30 degrees ; positive 30 to 60 degrees, positive greater than 60 degrees, or negative, and the surgical results were evaluated using a four-grade scale. Preoperatively, the SLR test was positive in 86% of patients. At 4 months postoperatively, 22% still had a positive SLR test. For the patients whose SLR test was positive 4 months postoperatively, the long-term outcome at all three follow-up examinations was inferior; this difference was statistically significant.

During the 2-year period, the reoperation rate was 18% (eight of 44) in patients with a positive postoperative SLR test compared with 4.5% (seven of 156) in patients whose postoperative SLR test was negative. A postoperative positive SLR test thus correlates to an unfavorable surgical outcome.