Anatomic position of a herniated nucleus pulposus predicts the outcome of lumbar discectomy.

The purpose of this study was to determine whether the anatomic position of a lumbar disc herniation has any significant effect on the clinical outcome of lumbar discectomy. Between January 1988 and March 1993, 80 patients with simple disc herniations underwent lumbar discectomy for herniated nucleus pulposus. We reviewed preoperative computed tomography scans after discography and magnetic resonance imaging of the lumbar spine. Disc herniations were classified as central, paracentral, intraforaminal, extraforaminal, or multiregional broad-based protrusions. The Smiley-Webster evaluation scale, which divided patients into groups with excellent, good, fair, and poor clinical outcome and evaluated the long-term need for pain medication, was applied. The post-operative evaluation period ranged from 6 to 48 months. The clinical outcome was then correlated with the different positions of herniations. The frequencies of the clinical outcomes were compared using the chi 2 test. We found a poorer clinical outcome that was statistically significant in patients with central herniations and with multiregional protrusions. Most herniations occurred at the L4-L5 level (58.7%). However, the level of disc herniation was not found to be a predictor of clinical outcome. Form and anatomic position of the lumbar disc herniation are of prognostic value for the outcome of lumbar discectomy. Further studies are required to confirm our preliminary results and eventually help improve surgical indications for lumbar discectomy.