Facet angles in lumbar disc herniation: their relation to anthropometric features.

STUDY DESIGN: Cross-sectional study. OBJECTIVE: To investigate the alteration of facet joint angle and its relation to anthropometric features in lumbar disc herniation. SUMMARY OF BACKGROUND DATA: In the previous studies, the facet tropism and its relation to the level, type, side, and development of lumbar disc herniation were reported. This study was the first to correlate anthropometric feature, facet angle, and asymmetry in patients with lumbar disc herniation. METHODS.: Sixty-one patients with lumbar disc herniation were included in this study. The body height, vertex-to-spina iliaca posterior superior distance, spina iliaca posterior superior-to-floor distance, and net weight were measured and body mass index calculated. The facet angles were measured for each facet joint using computed tomography. The intraobserver error was found to be +/- 1.66 degrees. We defined facet tropism as the bilateral angle difference greater than 2 intraobserver errors. The asymmetry rate was a ratio of degree of angles of the more coronally oriented facet joint to the more sagittally oriented facet joint at the same intervertebral level. RESULTS: The facet asymmetry was observed at the herniation level in 70.5% of the patients. There was a correlation between the degree of the more sagittally oriented facet joint angle and facet asymmetry rate at the herniation level (R = -0.684, P = 0.0001 for L4-L5 lumbar disc herniation; R = -0.509, P = 0.008 for L5-S1 lumbar disc herniation). The body height correlated with the degree of the more sagittally oriented facet joint angle, the degree of more coronally oriented facet joint angle, and asymmetry rate, respectively (R = -0.571, P = 0.0001; R = -0.474, P = 0.002; R = 0.314, P = 0.045, respectively). There was no correlation between the degree of these angles and the vertex-to-spina iliaca posterior superior distance. The spina iliaca posterior superior-to-floor distance was correlated with the degree of the more sagittally oriented facet joint angle (R = -0.457, P = 0.0001) and more coronally oriented facet joint angle (R = -0.435, P = 0.004) but not with the asymmetry rate. The degree of facet angles was not correlated with body weight and body mass index. CONCLUSION: This study revealed that patients with lumbar disc herniation had the asymmetry and sagittalization of facet joints, and these alterations were more evident in the taller patients.