Facet joint malorientation as a cause of disc degeneration and prolapse in cases with backache: A radiological analysis

Abstract

Background: Facet tropism is defined as asymmetry between the left and right vertebral facet-joint angles, with one joint having a more sagittal orientation than the other. The goals of the present investigation were to examine the association between facet tropism and disc degeneration as well as disc herniation to determine the relationship between increased sagittal orientation of the facet joint. It is postulated that non-coherent movements of facets on either side leads to an altered biomechanical stress which has to be borne by the anterior structure that is the disc this leading to disc degeneration and earlier prolapse. Methods: Axial and sagittal sections of MRI of the L4 L5 levels of 49 symptomatic adults aged between 20 to 60 years has been taken and their disc degeneration was classified from the T1 and T2 weighted MRI scans and facet tropism was graded as Mild (6-10 degrees), Moderate (11-15 degrees), Severe (>15 degrees). Results: It was observed from our study that the greater the grades of disc degeneration was found in patients with higher degrees of mal-orientation. There is a 5.893 times risk of dis degeneration in the cases of malorientation of the facet joint. There was no significant difference between the male and female population with regard to face tropism as a risk factor for disc degeneration. Conclusion: In our present study the association between the facet tropism as a risk factor for degeneration is positively established. The alteration in the biomechanical forces in the cases of facet tropism thus has led to faster disc degeneration. Keywords: Facet tropism, disc degeneration, facet malorientation IntroductionFacet tropism is defined as asymmetry between the left and right vertebral (apophyseal) facet joint angle, with one joint having a more sagittal orientation than the other. For years, it has been postulated that this could result in inter-vertebral disc degeneration and herniation. The results of several studies concerning the association between the facet tropism and disc degeneration had been conflicting each other [1,2,3] . With magnetic resonance imaging, it is possible to obtain data on tropism of facet joints and measure facet joint angles and disc degeneration at the corresponding level can be obtained in symptomatic volunteers without the risk of ionising radiation and also reducing the cost of the study [4,5] . The goals of the present study were to examine the association between facet tropism and disc degeneration as well as disc herniation and to determine the relationship between increased sagittal orientation of the facet joint at the level of L4-L5 with the help of the axial and sagittal sections of MRI of the L4 L5 levels.