The role and incidence of facet tropism in lumbar spine degenerative disc disease.

The correlation of posterior intervertebral (facet) joint tropism (asymmetry), degenerative facet disease, and intervertebral disc disease was reviewed in a retrospective study of magnetic resonance images of the lumbar spine from 100 patients with complaints of low back pain and sciatica. Of the 27 of 100 (27%) of patients discovered to have disc disease (either herniation of nuclear material or bulge) at the L4-5 level, an approximately equal number had facet tropism (14 of 27) as did not (13 of 27). Of the 27 of 100 (27%) patients noted to have disc disease at the L5-S1 level, slightly more (16 of 21) had facet tropism than did not (11 of 27). Of the 65 of 100 (65%) of patients who had facet degenerative disease at the L4-5 level, an approximately equal number had facet tropism (33 of 65) as did not (32 of 100). At the L5-S1 level there was slightly more of a difference, with 25 of 41 having facet degenerative joint disease and tropism and 16 of 41 without it. This study raises questions as to the significance of facet joint tropism in intervertebral disc disease and degenerative facet joint disease but did show that asymmetry of the posterior intervertebral joint is far more common than previously thought: 50% of patients were found to have asymmetric facets at the L5-S1 level and 42% at the L4-5 level.