Facet Tropism/Inclination and Its Association with Intervertebral Disc Herniation in the Lumbar Spine - A Radiological Evaluation.

Objective  To assess the role of facet tropism (FT) in intervertebral disc prolapse. Methods  A total 98 patients with lower back pain were included in the study. Magnetic resonance imaging scans were performed and analyzed. The angles of the right and left facets were measured on the axial section. Patients without disc prolapse at the L3-L4, L4-L5 and L5-S1 levels act as controls for those with disc prolapse at the same levels. A statistical analysis was also performed. Results  The incidence of FT at the L3-L4 level was of 85.2% in patients with disc herniation ( n  = 27), and of 56.3% in the control group, which was statistically significant ( p  = 0.008). Similarly, at the L4-L5 level, incidence of FT among cases and controls was of 71.4% ( n  = 35) and 52.4% respectively ( p  = 0.066). At the L5-S1 the incidence was of 66% and 51% among cases and controls respectively ( p  = 0.13). Conclusion  We found a positive association between FT and disc herniation at the L3-L4 level, but no association at the L4-L5 and L5-S1 levels.