Correlation Between The Spinopelvic Type And Morphological Characteristics Of Lumbar Facet Joints In Degenerative Lumbar Spondylolisthesis Based On Roussouly Classification

Objective: This study was conducted to observe the morphological characteristics of lumbar facet joints in degenerative lumbar spondylolisthesis(DLS)with different spinopelvic types based on Roussouly classification.To investigate the correlation between the spinopelvic type and morphological characteristics of lumbar facet joints,and to analyze the mechanism and explore its clinical significance.Methods: We retrospectively analyzed the medical records and images of all patients who visited the department of spine surgery in our hospital from August 2018 to June 2022.Based on the inclusion and exclusion criteria,we included 142 patients with L4 DLS in our study(DLS group),including 33 males and 109 females with a mean age of 62.6 ± 9.9 years.While 100 patients with L5–S1 lumbar disc herniation but normal L4–L5 in the same period were selected as the control group(i.e.,non–lumbar spondylolisthesis [NL] group),including 51 males and 49 females with a mean age of 47.9 ± 12.9 years.The following parameters were measured on preoperative 3D reconstructed CT images:(1)L4–L5 disc height and angle;(2)morphological parameters of the L4–L5 facet joints,including the facet joint angle(FJA),pedicle facet angle(PFA),facet joint tropism(FJT),and facet joint osteoarthritis(FJOA).The sacral slope(SS),lumbar lordosis(LL),and L4 slip distance were measured on preoperative standing neutral lumbar lateral radiographs,and the slip percentage(SP)was calculated.The disease duration and symptom scores of all patients were also recorded according to the medical records.Patients in the DLS and NL groups were divided into four subgroups according to Roussouly classification(types I,II,III,and IV).Differences in parameters such as morphological parameters of the facet joints and the SP were compared between the two groups and among the subgroups within the two groups,and the correlation between the FJA and PFA was also analyzed.Results: The differences in morphological parameters of the facet joints between the DLS group and NL group were statistically significant.Compared with the NL group,the DLS group had a greater PFA and FJT(P < 0.05),a more severe FJOA(P < 0.05),and a smaller FJA(P < 0.05).In the DLS group,the differences in the SP and morphological parameters of the facet joints were statistically significant among different subgroups.The SP was 19.1% ± 3.4%,18.6% ± 3.9%,21.7% ± 3.9%,and 25.0% ± 2.4% in type I,type II,type III,and type IV,respectively.No significant differences were found in the SP between type I and type II(P > 0.05).However,the SP values were higher in type III and type IV than in type I and type II and were higher in type IV than in type III.These differences were statistically significant(P < 0.05).The FJAs in type I(31.4° ± 6.3°)and type II(35.2° ± 6.8°)were larger than those in type III(28.4° ± 5.6°)and type IV(23.4° ± 4.5°).Moreover,type III was larger than type IV.Conversely,the FJAs in type I were smaller than those in type II.These differences were statistically significant(P < 0.05).In contrast to FJAs,the PFAs in type I(113.9° ± 4.9°)and type II(111.3° ± 5.6°)were smaller than those in type III(116.3° ± 4.4°)and type IV(121.8° ± 3.5°).Further,type III was smaller than type IV,while the PFAs in type I were larger than those in type II.These differences were statistically significant(P < 0.05).The degree of FJOA in both type I and type II was lower than that in type III and type IV.These differences were statistically significant(P < 0.05).However,no statistically significant differences in the degree of FJOA were found between type I and type II and between type III and type IV(P > 0.05).There were no statistically significant differences in the FJT values among type I,type II,type III,and type IV(P > 0.05).In the NL group,the comparison of facet joint morphological parameters among the four types revealed that they were similar to the DLS group.The FJAs in type I(47.0° ± 3.3°)and type II(50.5° ± 5.6°)were larger than those in type III(42.8° ± 6.2°)and type IV(37.0° ± 4.1°).Moreover,type III was larger than type IV.However,the FJAs in type I were smaller than those in type II.These differences were statistically significant(P < 0.05).In contrast,the PFAs in type I(104.4° ± 2.4°)and type II(101.6° ± 2.4°)were smaller than those in type III(106.8° ± 3.6°)and type IV(111.4° ± 3.5°).Moreover,type III was smaller than type IV.However,the PFAs in type I were larger than those in type II.These differences were statistically significant(P < 0.05).The degree of FJOA was lower in type I and type II than that in type III and type IV.These differences were statistically significant(P < 0.05).While there were no statistically significant differences in the degree of FJOA between type I and type II and between type III and type IV(P > 0.05).Additionally,there were also no statistically significant differences in the FJT values among type I,type II,type III,and type IV(P > 0.05).In both the DLS and NL groups,with the increase of the FJA,the PFA showed a decreasing trend.Pearson correlation analysis suggested that the FJA was negatively correlated with the PFA in the DLS group(r =-0.683,P <0.001)and NL group(r =-0.679,P < 0.001).Conclusion: In the slip segment of DLS,facet joint morphology was part of the joint configuration in different spinopelvic types,and DLS further aggravated the morphological remodeling of the facet joints.Morphological changes of the facet joints and DLS interacted with each other,and morphological remodeling of the facet joints in DLS played an important role in spinal balance and should be taken into consideration when designing a surgical approach.Understanding the sagittal spinopelvic alignment is helpful for the analysis of the correlation between spinal balance and degenerative spinal disease.