Comparison of L5 pedicle morphological parameters between patients with L5/S1 degenerative and isthmic spondylolisthesis and its clinical significance

English Keywords:Isthmic lumbar spondylolisthesis  Degenerative lumbar spondylolisthesis  Pedicle morphology  Imaging  Correlation

English Abstract:

  【Abstract】 Objectives: To measure the morphological parameters of L5 pedicle in patients with L5/S1 degenerative and isthmic spondylolisthesis, compare their differences and analyze their clinical significance. Methods: The imaging data of patients with L5/S1 spondylolisthesis admitted to the Affiliated Hospital of Southwest Medical University from January 1, 2016 to June 30, 2020 were collected. There were 119 patients with L5/S1 isthmic spondylolisthesis(IS group) and 45 patients with L5/S1 degenerative spondylolisthesis(DS group), and 164 non- spondylolisthesis patients with lumbar disc herniation were selected as the control group(NS group). The morphological parameters of L5 pedicle of the three groups of patients were measured on multi-slice computed tomography(MSCT) images, including pedicle length(PL), pedicle screw trajectory length(PSTL), pedicle width(PW), pedicle height(PH), and pedicle camber angle(PCA). The slipping distance of L5 vertebra was measured on standing neutral lateral X-ray film, and the percentage of slip was calculated. The differences of L5 pedicle morphological parameters between the three groups were compared, and the correlation between morphological parameters and slip degree was analyzed. Results: There was no significant difference in sex ratio, height, weight and body mass index(BMI) among the three groups of patients(P>0.05). There was no statistical difference between the left and right parameters of the three groups. The PL, PSTL, PW, PH, and PCA of IS, DS, and NS groups were respectively 14.4±2.1mm, 48.3±4.2mm, 13.6±2.1mm, 9.6±1.5mm, and 29.7°±5.3°; 16.2±1.6mm, 49.8±3.3mm, 11.3±1.9mm, 9.7±1.7mm, and 23.3°±6.5°; 15.1±1.7mm, 48.5±3.5mm, 12.7±1.9mm, 10.8±1.3mm, and 27.3°±4.7°. The values of PL and PSTL in DS group were significantly higher than those in IS group(P<0.05), and the values of PW and PCA were significantly smaller than those in IS group(P<0.05), and there was no significant difference in PH between the two groups(P>0.05). There were significant differences in PL, PW, PH, PCA between IS group and NS group(P<0.05), while there was no significant difference of PSTL between these two groups(P>0.05). There were significant differences in PL, PSTL, PW, PH and PCA between DS group and NS group(P<0.05). The slipping distance(11.2±2.7mm) and percentage of slip(29.1±10.9)% of IS group were higher than those in DS group[8.8±2.4mm, (24.4±8.4)%](P<0.05). Pearson correlation analysis showed that there was no significant correlation between the percentage of slip and the parameters of L5 pedicle of IS group(P>0.05); In DS group, the percentage of slip was positively correlated with PL(r=0.640, P=0.0001), and negatively correlated with PW(r=-0.510, P=0.0001) and PCA(r= -0.405, P=0.006), while it has no significant correlations with PSTL(P>0.05). Conclusions: There are differences in the morphology of pedicle of the slipping vertebra between degenerative and isthmic spondylolisthesis. The L5 pedicle morphology in L5/S1 isthmic spondylolisthesis is more abducted, shorter, and wider, while that in the degenerative spondylolisthesis is more adducted, longer, and thinner comparing with the normal populations, suggesting that there is differential stress remodeling of pedicle in the development of spondylolisthesis in patients with the two types of spondylolisthesis.