Predictors Of The Loss Of Cervical Lordosis After Posterior Cervical Double-door Laminoplasty

Background:Posterior cervical laminoplasty is one of the advanced methods for the treatment of multilevel cervical degenerative diseases.However,although some patients have cervical kyphosis before operation,they still have cervical curvature loss or kyphosis after operation,which can affect the effect of spinal cord decompression and long-term clinical prognosis.At present,although some scholars have pointed out that the risk factors of cervical curvature loss after laminoplasty include age,T1 tilt angle and posterior cervical muscle injury,there are differences in surgical methods,surgical segment range and measurement indexes in different studies.therefore,the predictive factors of postoperative cervical curvature loss are still controversial.Therefore,the purpose of this study was to systematically investigate the effect of posterior double open-door laminoplasty(C3-C6)on postoperative cervical curvature and therapeutic effect.Objective:To explore the predictive factors of imaging and clinical parameters of cervical curvature loss after double open door laminoplasty,and the correlation between postoperative cervical curvature loss and treatmenteffect.Methods:The clinical and imaging data of 65 patients with multilevel cervical Spondylotic myelopathy(multilevel cervical spondylotic myelopathy,MCSM)who underwent posterior double open-door laminoplasty in our hospital from January 2013 to December 2018 were analyzed retrospectively.The imaging parameters included preoperative C2-C7 Cobb angle,preoperative C0-C2 angle,preoperative T1 tilt angle(T1-Slope),preoperative C2-C7 range of motion(range of motion,ROM),preoperative C2-C7 sagittal vertical axis(C2-C7 sagittal vertical axis)and preoperative head center of gravity sagittal vertical axis(center of gravity of the head-C7 sagittal vertical axis,CGH-C7SVA).Clinical factors include age,sex and body mass index.The evaluation indexes of clinical efficacy include JOA score and JOA improvement rate before and after operation.Loss of Cervical Lordosis(Loss of Cervical Lordosis,LCL)=(preoperative C2-C7 Coob angle)-(last follow-up C2-C7 Cobb angle).T-test,Pearson correlation test,univariate and multivariate linear regression analysis were used to explore the predictive factors of postoperative cervical curvature loss of LCL,and to explore the correlation between LCL and postoperative JOA score and JOA improvement rate.Results:The patients were divided into high and low groups according to the median of T1-Slope(26.60).Independent sample t-test was used to compare the results between the two groups.The results showed that there were significant differences in C2-C7 Cobb angle,C2-C7 SVA angle and LCL angle between the two groups,but there were no significant differences in age,BMI,C0-C2 angle,C2-C7 activity and CGH-C7 SVA between the two groups.Univariate analysis showed that T1-Slope(P < 0.001)and C2-C7SVA(P < 0.001)had statistical significance,while the other indexes had no statistical significance.The statistically significant factors in univariate analysis were included in multivariate analysis,and the results showed that T1-Slope(P < 0.001)and C2-C7SVA(P < 0.001)were statistically significant.Furthermore,the correlation between imaging parameters was discussed by Pearson correlation analysis.The results showed that there was a significant positive correlation between C2-C7 SVA(mm)and T1-Slope and LCL(P < 0.001),and there was a positive correlation between T1-Slope and LCL(P < 0.001),and the correlation coefficient was 0.65.The results showed that there was a significant positive correlation between T1-Slope and LCL(P < 0.05).Finally,the correlation between LCL and clinical prognosis was discussed.There was a negative correlation between JOA improvement rate and LCL(P < 0.001),and the correlation coefficient was-0.583.Conclusion:T1-Slope and C2-C7 SVA can be used as predictors of cervical curvature loss after double-door laminoplasty,and the greater the cervical curvature loss,the lower the postoperative JOA improvement rate.