Sagittal morphological classification of degenerative lumbar spondylolisthesis and its clinical significance

English Keywords:Lumbar degenerative spondylolisthesis  Anterolateral lumbar interbody fusion  Sagittal morphology classification  Spinopelvic parameters

English Abstract:

  【Abstract】 Objectives: To investigate a new classification of lumbar degenerative spondylolisthesis(DS) based on the features of sagittal morphology, and evaluate its value in anterolateral approach surgery for DS. Methods: From January 2015 to December 2016, 37 cases with L4 DS were analyzed retrospectively, including 15 males and 22 females. The age ranged from 50 to 67 years(58.5±9.5 years). According to sagittal morphology, the patients were divided into three groups by 3 observers: opened type with SA(sagittal slipping angle)>5°, parallel type with 0°≤SA≤5°, and closed type with SA<0°. All patients were treated with anterolateral lumbar interbody fusion(ALLIF). In the surgical procedure, operative position, cage placement and fixation were adjusted according to sagittal morphology type. The followings were recorded: the pre- and postoperative spino-pelvic parameters including lumbar lordosis(LL), pelvic incidence(PI), pelvic tilt(PT), sacral slope(SS), sagittal vertical axis(SVA), and clinical scores including VAS for low-back and leg pain, ODI for functional disability, SF-36 for quality of life. The Kappa consistency test was performed on the classification results from the three observers, and the clinical data of each group was also statistically analyzed. Results: The Kappa of intra-observer agreement was 0.826-0.894, and the Kappa of intra-observer was 0.875-0.916, both of which were highly consistent. Of the 37 patients, 12 cases were open type(group A), 17 cases were parallel type(group B), and 8 cases were closed type(group C). There were significant differences of preoperative PT, SS and LL among the groups(P<0.05), and closed type had the lowest LL and SS in all subtypes(P<0.05), but no difference was found in PI and SVA(P>0.05). There was no significant change in spino-pelvic parameters of group A and B before and after surgery(P>0.05). While in group C, PT decreased, and SS, LL increased significantly(P<0.05). The preoperative VAS for low back pain in group C was significantly higher than those in the other two groups(P<0.05). The postoperative VAS for low back pain and leg pain, ODI, SF-36 scores were significantly improved(P<0.05). The improvement of VAS for low back pain, ODI and SF-36 mental component summary(MCS) scores in group C were greater than those in the other two groups(P<0.05). Conclusions: This new sagittal morphological classification system is a simple and reliable method for classifying DS cases, based on which the ALLIF treatment can achieve satisfactory clinical outcomes.