The Relation Of Degenerative Lumbar Spondylolisthesis And The Characteristic Of Lumbar Facet Fluid Detected On Magnetic Resonance Imaging

Objective: With the aging of the population trends,the incidence rate of degenerative lumbar spondylolisthesis is increasing every year. The etiology is not yet entirely clear, possible reasons for disc degeneration, facet joint morphology abnormalities, racial factors, soft tissue abnormalities, changes in lumbosacral angle,and so on. In recent years, the role of facet joint morphology in the pathogenesis of degenerative spondylolisthesis is the focus of discussion, but more concentrated on the CT manifestations of joint angle and osteoarthritis. Several studies have found that degeneration of the lumbar facet joints is coupled to intervertebral disc degeneration, both of which are important contributors to instability. Mailleux et al reported that facet fluid detected on MRI showed that the presence of lumbar instability. Fujiwara et al found that facet fluid of T2 MRI images correlated positively with segmental instability of the lumbar spine in patients with degenerative lumbar spinal diseases.The study to investigate the association between lumbar facet fluid on MRI and sagittal vertebral body anterior slip on lateral lumbar radiographs in patients with degenerative lumbar spondylolisthesis.Methods: Retrospective analysis of the X-ray and MRI information of 53 patients who suffered degenerative lumbar spondylolisthesis and treated in our Spinal Department from August 2007 to January 2009.There were 21 males and 32 females with an average of 58.6 years (41-73 years).All cases were L4 vertebral body anterior slip,no deformity, cyclorotation and lateral slip of vertebral body,exclude to tuberculosis,inflammation,trauma,tumor et al. Lumbar spondylolisthesis was defined as the presence of anterior translation of L4 on L5 in the sagittal plane.The percentage slip of L4 on L5 was calculated by measuring the amount of anterior slip of L4 on L5 (using the posterior cortices of the L4 and L5 vertebrae as references), dividing this value by the sagittal width of the superior endplate of the L5 vertebra, and multiplying this number by 100. Axial T2-weighted MRI sequences through the L4–L5 facet were analyzed for the presence of facet fluid. The facet fluid index for L4–L5 was defined as the ratio of the sum of the width of fluid in each facet (bilateral) to the sum of the width of both of the facets (bilateral) on the axial MRI. The measurement is to draw the sagittal and the horizontal line in the upper and lower edge of each of facet joints in the axial T2 MRI images. To the intersection of two lines as a starting point for a straight line, with the horizontal 45°.The a is the distance of between starting point and the intersection of straight line with the upper articular process lateral edge. The distance of straight line through the facet joints high-intensity zone is b.Therefore, The facet fluid index for L4–L5 was defined as(bL+bR)/(aL+aR).All measurements (radiographic and MRI) were taken by an independent examiner who was not directly involved with the care or surgery of the patients. All data were entered into a computerized database. Statistical analyses were performed with SPSS,version 12.0.1, for a personal computer. Pearson's correlation coefficient was calculated to analyze the association between the facet fluid index and the slip percentage. Significance was set at a P value of ₀.05. Odds ratios were calculated using a confidence interval (CI) of 95%.In order to assess interobserver reliability, the intraclass correlation coefficient was calculated using the measurements taken by the two independent examiners for both the facet fluid index and the percent of radiographic slip of L4 on L5. In order to assess the intraobserver reliability, the intraclass correlation coefficient was calculated using the initial and repeated (1 month after initial) measurements of the facet fluid index and the percent of radiographic slip of L4 on L5. All measurements were taken using the measurement tool function of Adobe Photoshop (San Jose CA, 2005).Results: Fifty-three patients were included in the study,43 (81.13%) of whom had facet fluid noted on MRI. Of those patients who did not have facet fluid on the MRI, all had minor vertebral body anterior slip on the lateral lumbar radiograph(