Lumbar facet joint asymmetry. Intervertebral disc herniation.

A study of 136 patients with lumbar intervertebral disc herniation was undertaken to test the hypothesis that asymmetry of the facet joints is associated with the level, type, and side of herniation. Fifty cases of central herniation and 86 cases of lateral herniation, all at the L4-5 or L5-S1 levels, were studied by computed tomographic scans. Adjacent (nonherniated) levels were used as controls. The facet joint angles were measured at the L4-5 and L5-S1 levels of the control, central, and lateral herniated levels. The results showed a similar degree of facet joint asymmetry at all levels. In cases of lateral herniation, there was a significant difference in the facet angle between the herniated and nonherniated side at the L5-S1 level, but not the L4-5 level. The mean difference, however, was less than 3 degrees and not considered to be clinically relevant. There was no difference in the distribution of the more coronally or sagittally facing facet joints with respect to the side of lateral herniation. These results do not support the hypothesis that facet asymmetry is associated with lumbar intervertebral disc herniation.