2011 年 25 巻 2 号 p. 203-208
Microscopic bilateral spinal decompression via unilateral laminotomy (MBDUL) is one of the less-invasive surgeries for lumbar canal stenosis (LCS). Although this surgical technique is now familiar to many spinal surgeons, some difficulties are encountered in preserving the facet joint in the side in which laminotomy is performed and in achieving adequate decompression in the contra-lateral side. In this report, we describe some anatomical landmarks that are helpful for achieving these surgical goals. Before bone cutting, we roughly determined the extent to which laminotomy could be performed on the basis of the following landmarks ; (1) the notch in the upper lamina, (2) the caudal end of the inferior articular process, and (3) the lateral edge of the pars interarticularis. When performing medial facetectomy, we observe the capsular portion of the yellow ligament and the medial edge of the pedicles of the lower vertebra. These landmarks help determine the necessary and adequate extents to which facetectomy and ligamentectomy should be performed. This knowledge can help preserve the facet joint even during surgical decompression of the upper lumbar spine. In the 19 cases examined in the study, the mean duration of post-operative hospital stay was 13.2 days (range, 4-30 days), and the mean period for the patients to return to their previous work was 24.0 days (range, 4-60 days). None of the patients developed spinal instability during the follow-up (mean follow-up period, 39.2 months). Japanese Orthopedic Association scores and visual analogue scale scores for pain and numbness improved after the operation, and the scores were maintained at the final follow-up performed after more than a year. These findings suggest that adequate neural decompression was achieved with MBDUL. In conclusion, the anatomical landmarks described above are useful for constantly achieving good surgical outcomes with MBDUL.