Prevalence of Facet Tropism in Lumbar Spine among South Indian Population: An MRI-based Radiological Study in 400 Patients

Ab s t r Ac t Background: Facet tropism (FT) is the presence of asymmetry in the sagittal angulations of the bilateral facet joints, which is proposed to be a contributing factor for certain spinal disorders. Few studies are present in literature discussing the prevalence of FT in the lumbar spine among the South Indian population and our study shall focus on this by identifying it on MR imaging. Materials and methods: It is a cross-sectional study, where 400 lumbar MRI scans of patients with low back pain without trauma, deformities, and surgical history were studied between 2016 and 2019. Facet angles are measured and the presence of FT and its severity is assessed on axial sections in all the patients. Data is subjected to statistical analysis. Results: One hundred and eighty-two (45.5%) females and 218 (54.5%) males are included in this study. The age range is 26–86 years and the mean ages of the female and male samples are 52.89 ± 14.06 and 52.31 ± 13.62 years. Facet tropism is seen in 178 (44.6%) individuals and is noticed at all levels from L1 to S1. The presence of FT is 2% at L1-L2, 12.9% at L2-L3, 13.9% at L3-L4, 28.7% at L4-L5, and 21.8% at L5-S1. The degree of tropism was severe at the L4-L5 intervertebral level in 5.9% of the study population. Age and gender do not have a significant correlation with the presence of tropism. All the above results have attained statistical significance. Conclusion: The presence of FT is not uncommon, although its incidence varies at each level of the lumbar spine. The prevalence of FT in our study population is 44.6%. The highest prevalence of FT and a severe degree of FT were noticed in the L4-L5 level.