Age- and sex-related changes in facet orientation and tropism in lower lumbar spine: an MRI study of 600 patients

PurposeWe aimed to determine the age- and sex-related changes in facet orientation and facet tropism in lower lumbar spine.MethodsBetween June 2015 and December 2017, magnetic resonance imaging scans of the consecutive 600 patients performed in the outpatient department for low back pain were analyzed. The data were divided according to age into four groups: group A (<30years), group B (31-45years), group C (46-60years) and group D (>60years). The orientation of the facet angles at L3-4, L4-5 and L5-S1 was measured using the method described by Noren et al. Sagittal angles and tropism were determined at each level.ResultsAverage facet angle is noted to increase from L3-4 to L5-S1 level in all groups irrespective of age and sex. A positive correlation is noted between age and sagittal facet orientation at all levels across all groups. Tropism was noted to be statistically significant (p<0.05) at L5-S1 level. L3-4 and L4-5 levels did not show a positive correlation with respect to age. Facet angle sagittalization was significantly associated in males at L5-S1 level (p<0.05) and in females at L4-5 level (p<0.05).ConclusionsPredominant morphological changes in superior articular process are responsible for remodeling of facets that occur with increasing age, resulting in sagittalization. Even though the facet orientation changes over a period of time, differential changes within the facets at the same level might not be seen. [GRAPHICS] .