Preliminary Establishment Of Personalized Sagittal Plane Reconstruction Model Of Degenerative Scoliosis

Objective:To analyze the spinal-pelvic parameters after posterior lumbar decompression and fusion for degenerative scoliosis(DS),and construct a personalized sagittal reconstruction model in order to obtain the best surgical effect.Methods:Part one:A total of 96 patients with DS from January 2013 to May 2018 were analyzed retrospectively,including 45 cases of long segment group(>3segments)and 51 cases of short segment group(? 3 segments).The clinical efficacy was evaluated by visual analogue scale(VAS)and Oswestry disability index(ODI)before operation and during follow-up.The following spine-pelvic parameters were measured: coronal Cobb angle,spinal sagittal plane balance(SVA),thoracic kyphosis angle(TK),thoracolumbar kyphosis angle(TLK),lumbar kyphosis angle(LL),pelvic incidence angle(PI),pelvic inclination angle(PT),sacral slope(SS).Meanwhile,the postoperative complications of the patients were also recorded.The imaging parameters,clinical efficacy and complications of the two groups were analyzed and compared.Part two:The spinal-pelvic parameters of patients with sagittal imbalance were analyzed.According to the 75 th percentile cutoff of ODI index at the last follow-up,the patients were divided into mild disorder group(n = 32)and severe disorder group(n = 15).Logistic regression analysis was used to find out the independent risk factors affecting the clinical effect.Sub-groups were divided to explore the clinical efficacy of different sagittal plane balance(SVA)and PI-LL matching after sagittal plane reconstruction.Part three:The spinal-pelvic parameters of DS patients with sagittal reconstruction after posterior lumbar decompression and fusion were analyzed.The prediction equation of postoperative SVA was derived by stepwise multiple regression analysis,and then through mathematical operation with the ideal SVA equation,the prediction equation of reasonable lumbar kyphosis was calculated,and its effectiveness was evaluated by transverse comparison with other lumbar lordosis prediction models.Results:Part one:The time of operation,the amount of intraoperative blood loss and the number of intraoperative fluoroscopy in the long segment group were higher than those in the short segment group(P < 0.05).At the last follow-up,the VAS score and ODI index of low back pain and lower limb pain in the two groups were significantly improved compared with those before operation(P<0.01),but there was no significant difference in lower limb pain VAS and ODI between the two groups(P > 0.05).The VAS improvement of low back pain in the long segment group was more significant than that in the short segment group(P<0.05).Compared with pre-operation,Cobb,SVA,TLK and PT in long segment group decreased significantly(P<0.05),and SS and LL increased significantly(P<0.05);while in short segment group,only PT decreased and SS increased(P<0.05).The incidence of complications in the long segment group(33.33%)was significantly higher than that in the short segment group(19.61%)(P<0.05).Part two:At the last follow-up,the Cobb's and SVA,TK,PT,PI-LL of the severe disorder group were significantly higher than those of the mild disorder group,while the LL of the severe disorder group was lower than that of the mild disorder group(P < 0.05).Logistic regression analysisshowed that SVA,LL,PT and PI-LL were independent risk factors for OID improvement after DS(P<0.05).There was no significant difference in ODI between 26 patients with SVA ? 50 mm and 16 patients with 50 mm <SVA < 95mm(P > 0.05).ODI in 5 patients with SVA ? 95 mm was higher than that in patients with 50 mm < SVA < 95mm(P < 0.01).The ODI between the PI-LL matching group and PI-LL mismatch group had no significant difference at the last follow-up(P > 0.05).Part three:There was a significant correlation between SVA and TK(r = 0.325,P<0.01)and PI(r = 0.392,P<0.01).The prediction formula of SVA is obtained by multivariate linear analysis: SVA=2.48PI-4LL+90.92;The prediction model of LL: LL=0.62~*PI-(Age-55)/2+16.48 was deduced combined with ideal SVA=2~*(Age-55)+ 25.Compared with other models,the average gap between the ideal LL predicted by this model and the actual LL is 4.2 ±2.4 °,which has good prediction value.Conclusion:1.Short-segment fixation has less trauma and fewer complications,while long-segment fixation has more advantages in improving spine-pelvic parameters and relieving low back pain.2.The slight sagittal imbalance after operation has no significant effect on the quality of life of the patients,and LL=PI ±9 °may not be suitable as an orthopedic target for Chinese.3.LL=0.62~*PI-(Age-55)/2+16.48,which can provide a new perspective for personalized sagittal reconstruction.