[The relationship of facet orientation to intervertebral disc protrusion and lateral recess stenosis in lower lumbar spine].

OBJECTIVE: To investigate the relationship of facet orientation to intervertebral disc protrusion and lateral recess stenosis in lower lumbar spine. METHOD: The relationship between facet geometry (joint angle and tropism) and disc protrusion, lateral recess stenosis was investigated with computer tomography (CT) at the vertebral levels L(3 - 4), L(4 - 5), and L(5) - S(1). 772 facet joint angles (386 lower lumbar levels of 136 patients) were measured on coronal CT scans by transverse inter-facet angle (TIFA). RESULT: There was no statistically significant relationship between facet joint asymmetry and disc protrusion (P > 0.05). Disc protrusion occurred more frequently on side of sagittally oriented facet joint than coronal side (P < 0.01). The patients whose lumbar transverse inter-facet angle less than 20 degrees easily suffered from degenerative lumbar lateral recess stenosis in the elderly. The TIFA in Asian less evident than in European may be the important cause for high incidence of lumbar lateral recess syndrome in Asia. CONCLUSION: Stress on the lower lumbar spine leads to disc protrusion. No association is found between facet joint asymmetry and lumbar disc protrusion. The asymmetry of facet joint will influence the direction of intervertebral disc protrusion at level from L(4) - S(1). The patient whose lower lumbar spine inter-facet angle may unlikely suffer from degenerative lumbar lateral recess stenosis.