Assessment of lumbar spinal canal morphology with digital computed tomography.

BACKGROUND The study of lumbar spine pathology requires adequate preparation and knowledge of the normal structure of this part of the spine. The main goal of the study was to assess spinal canal morphology with computed tomography. The sagittal and interpedicular dimensions and surface area were considered the most important measurements. An additional goal was to assess the shape of the spinal canal and intervertebral joint angles. MATERIAL AND METHODS Computed tomography was used to assess the lumbar spinal canals of 42 people to an accuracy of 0.01 using a special console for digital analysis. RESULTS The mean sagittal dimension showed minor differences and ranged from 15.75+/-0.886 at the L3 level to 17.77+/-1.619 at the L5 level. The mean interpedicular dimension was significantly different between the levels, increasing from 24.75+/-2.173 at L3 to 34.57+/-3.332 at L5. Similar results were obtained as regards the mean surface area of the spinal canal. The surface area was 277.2+/-36.15 mm2 at the L3 level, compared to 297+/-9.90 mm2 at L4 and 386.5+/-50.55 mm2 at L5. The spinal canal shape at the L4-L5 level was triangular or trefoil in all 42 patients. No significant differences were found between the angles of right and left intervertebral joints. CONCLUSIONS Our results do not differ from those described in literature. A sagittal dimension over 15 mm, and an interpedicular dimension of more than 25 mm are characteristic of a normal spinal canal. The results constitute reference data for further studies concerning lumbar stenosis.