Assessment of spinal canal shape and intervertebral joint angles in lumbar spine.

BACKGROUND Publications concerning the shape of the spinal canal and degenerative changes in the intervertebral joints have not described this issue in full detail to date, especially with regard to the causes of pain syndromes associated with degenerative changes in intervertebral joints. The aim of the study was to assess the shape of the spinal canal and joint surface angles at L3, L4 and L5. MATERIAL AND METHODS The study involved 176 patients with clinical and radiological evidence of spinal canal stenosis confirmed by computed tomography. RESULTS Morphometric measurements were conducted to a precision of 0.01 degrees . At the level of L4-L5, a triangular spinal canal was found in 66 patients, and a trefoil spinal canal in 71. The results demonstrate that, in the group of 176 patients with spinal canal stenosis, mean differences between right and left angles were 11.37 degrees at the L3 level, 9.40 degrees at the L4 level, and 11.57 degrees at the L5 level. In the control group, mean differences were 2.15 degrees at the L3 level, 2.26 degrees at the L4 level, and 2.98 degrees at the L5 level. Statistically significant differences between the groups were found for p= 0.05 at each level (L3, L4, L5). The level of significance of angular differences at these levels warrants the conclusion that there is joint incongruence that may give rise to degenerative changes. CONCLUSIONS While the most common pathomechanism underlying degenerative changes is vertebral sinking in the course of disc disease and emerging intervertebral instability, abnormal intervertebral angles can also lead to instability that gives rise to degenerative changes.