Shinto K, Minamide A, Hashizume H, et al. - From the Wakayama Spine Study, researchers assessed 808 participants who underwent MRI investigations in supine position in order to determine the prevalence of facet effusion in the general population and to define its possible relationship with spondylolisthesis and low back pain. They identified this work be the first population-based cohort study of facet effusion. A measurable, curvilinear, high-intensity signal within the facet joint, closely matching that of cerebrospinal fluid on the axial T2 images, defined the facet effusion. Facet effusion was prevalent in the lumbar spine of 34.3% of individuals. No significant differences in facet effusion were observed between men and women and further, it did not tend to increase with age, either in men or in women. Furthermore, no significant association was observed between facet effusion and low back pain, or between facet effusion and L4 spondylolisthesis. In a subset of participants with L4 spondylolisthesis, no significant association of facet effusion with low back pain was observed.