The effect of limited interlaminar decompression versus complete laminectomy on intrathecal volume in degenerative lumbar spinal stenosis.

Introduction: There is a controversial discussion about the adequate surgical procedure for degenerative lumbar spinal stenosis. Due to the observation that the degenerative lumbar spinal stenosis takes place predominantly at the interlaminar region on the level of the disc involving facets and bulging of the ligamentum flavum, resection of the whole lamina might not be necessary. A biomechanical study was designed to assess the effect of different decompression techniques using cadaver lumbar spine models. Methods: Twelve cadaver spines with CT verified degenerative lumbar spinal stenosis were dissected in order to measure the volume of the dural sac at different flexion and extension angles. Each segment (L3/4, L4/5) was decompressed first by limited interlaminar decompression and second by complete laminectomy. Intrathecal volume measurements were taken initially, after limited interlaminar decompression and after complete laminectomy. Results: Before surgical procedure, the cadaver spines showed an increase of the intrathecal volume in flexion and decrease in extension. After limited interlaminar decompression, there was a significant reduction of volume loss in extension. There was no significant additional reduction of volume loss in extension after complete laminectomy in comparison to limited interlaminar decompression. Conclusion: The results allow to conclude that limited interlaminar decompression is efficient for decompression in degenerative lumbar spinal stenosis.