Effect Of Posterior Cervical Expansive Open-door Laminoplasty On Cervical Sagittal Balance

Objective:To explore the changes of cervical sagittal balance after posterior cervical expansive open-door laminoplast.Methods:To collect the clinical and radiological data were analyzed retrospectively for 108 patients undergoing posterior cervical open-door expansive laminoplasty(C3-C7)in Department of Orthopaedic Surgery,Shanxi Bethune hospital,from January 2014 to December 2017.JOA score,NDI score,SF-36 score,VAS scrore and 4 cervical sagittal parameters including C0-2Cobb angle,C2-C7 SVA,C2-7Cobb angle,T1-Slope on lateral cervical X-rays were both recorded before operation and at the 24-months after operation.Results:The JOA score and SF-36 score rose to(14.08 ± 2.17),(51.25 ± 5.82)from pre-op(11.16±2.28),(42.76±5.63).The NDI score and VAS score decreased from(15.61±5.43),(4.64±1.87)before surgery to(11.36±7.93),(3.31±1.62)at follow-up,all of the changes were statistically significant(P=0.001,P=0.001,P=0.001,P=0.022).The C0-2Cobb angle,C2-7 SVA rose to(15.36±4.51)°,(25.49±11.52)mm form(11.37±5.54)°and(21.09±5.86)mm,C2-7Cobb angle decrease from(13.93±8.68)°to(10.6± 8.72)°,the value changes were all respectively statistically significant(P=0.001,P=0.001,P=0.016).T1-slope changed from(26.84 ± 5.10)° before operation to(26.31 ± 4.8)° at follow-up,the difference was not statistically significant(P=0.186).The change in C0-2Cobb angle is positively related to the change in C2-7SVA(Pearson=0.420,P=0.015).At the last time follow-up,the average VAS score ofhigh T1 group(3.13±1.60)and low T1 group(2.45±1.31)were statistically significant(P=0.015).The incidence of obvious axial symptoms was 64.8% in the high T1-Slope group and 33.3% in the low T1-Slope group.Conclusion:To sum up,the posterior cervical expansive open-door laminoplasty has a certain influence on the sagittal balance of the cervical spine.The cervical spine shows a tendency of forward leaning.However,through the compensation of over extension of the upper cervical spine,the whole cervical spine can be kept stable,and the normal center of gravity and line of sight of the head can be maintained.Patients with high T1-Slope and low T1-Slope have satisfactory neurological recovery and Clinical curative effect,but patients with high T1-Slope may have more serious neck pain symptoms.Therefore,for patients with high T1-Slope before operation,more attention should be paid to the exercise of neck muscles after operation,so as to reduce or reduce the impact of axial symptoms on the quality of life.