BACKGROUND: Epidural fibrosis or scar formation is considered one cause of failed lumbar discectomy. Avoidance of unnecessary bony resection of the lamina may prevent or decrease postoperative scar formation. The knowledge of the precise location of the projection of the lumbar disc may also facilitate surgery and decrease patient morbidity. No studies exist regarding the projection of the lumbar disc on the posterior aspect of the lumbar spine. METHODS: Thirty-six whole lumbar spine specimens from L1 to L5 (180 lumbar vertebrae) and sacra were used for this study. Anatomic evaluation included the distance between the superior border of the vertebral body (inferior border of the intervertebral disc) and the superiormost margin of the lumbar lamina, and the distance between the inferior border of the vertebral body (superior border of the intervertebral disc) and the inferiormost margin of the lumbar lamina. The width of the interlaminar space was also measured. RESULTS: The data showed that the level of the superior margin of the lamina was consistently inferior to the superior border of the corresponding vertebral body from L1 to S1. This distance for both sexes ranged from 10 to 11 mm for L1-L5 and 14 mm for S1. The level of the inferior margin of the lamina varied from 3 mm inferior to 9 mm superior to the inferior border of the corresponding vertebral body for L1-L5. The width of the interlaminar space averaged from 16.8 mm for L1 to 31.0 mm for L5. CONCLUSIONS: This study suggests that the superior margin of the lamina represents a consistent, useful landmark in determining the location of the lumbar disc on the posterior aspect of the spine. The relationship between the inferior margins of the lamina and the vertebral body is not consistent.
BACKGROUND: Epidural fibrosis or scar formation is considered one cause of failed lumbar discectomy. Avoidance of unnecessary bony resection of the lamina may prevent or decrease postoperative scar formation. The knowledge of the precise location of the projection of the lumbar disc may also facilitate surgery and decrease patient morbidity. No studies exist regarding the projection of the lumbar disc on the posterior aspect of the lumbar spine. METHODS: Thirty-six whole lumbar spine specimens from L1 to L5 (180 lumbar vertebrae) and sacra were used for this study. Anatomic evaluation included the distance between the superior border of the vertebral body (inferior border of the intervertebral disc) and the superiormost margin of the lumbar lamina, and the distance between the inferior border of the vertebral body (superior border of the intervertebral disc) and the inferiormost margin of the lumbar lamina. The width of the interlaminar space was also measured. RESULTS: The data showed that the level of the superior margin of the lamina was consistently inferior to the superior border of the corresponding vertebral body from L1 to S1. This distance for both sexes ranged from 10 to 11 mm for L1-L5 and 14 mm for S1. The level of the inferior margin of the lamina varied from 3 mm inferior to 9 mm superior to the inferior border of the corresponding vertebral body for L1-L5. The width of the interlaminar space averaged from 16.8 mm for L1 to 31.0 mm for L5. CONCLUSIONS: This study suggests that the superior margin of the lamina represents a consistent, useful landmark in determining the location of the lumbar disc on the posterior aspect of the spine. The relationship between the inferior margins of the lamina and the vertebral body is not consistent.