Preoperative Prediction Of Micro-titanium Plate Size And Analysis Of Related Parameters In Cervical Open-door Angioplasty

Objective: To predict the size of the centerpiece titanium plate used in the operation according to the measurement of the relevant door opening parameters before the operation,so as to achieve the expected door opening size after the operation.Methods: From July 2018 to December 2019,28 patients with multilevel cervical spondylotic myelopathy were treated by posterior single door laminoplasty,including 17 males and 11 females,aged 42-64 years.The geometric model of cervical cross section was established before operation,and the functional relationship between the opening parameters was deduced,and the size of titanium plate used in operation was predicted by the functional formula.The related parameters were measured on the cross-section of cervical CT taken before and after operation.Statistical method was used to analyze the difference between the actual opening angle（θ ’）and the predicted opening angle（θ）before operation,so as to verify the feasibility of the prediction method.At the same time,analyze and compare the differences between other door opening parameters.Results: All the patients recovered well and no obvious complications occurred.There was no significant difference between the predicted opening angle θ before operation and the actual opening angle θ ’after operation（P > 0.05）;there was no significant difference between the actual increasing value of the cross-sectional area of the spinal canal（Δs’）and the increasing value of the cross-sectional area of the spinal canal（Δ s’）calculated according to the formula（P > 0.05）;there was a significant difference between the preoperative midsagittal diameter of the spinal canal（d1）and the postoperative midsagittal diameter of the spinal canal（d2）There was statistical significance（P < 0.01）,and there was statistical significance（P < 0.01）in the difference between the preoperative cross-sectional area of spinal canal（S1）and the postoperative cross-sectional area of spinal canal（S2）;there was statistical significance in the difference between the actual added value of the sagittal diameter of spinal canal（d2-d1）and the predicted opening sagittal diameter（Δd）before operation（P < 0.01）.Conclusion: The open angle of single open door operation of cervical spine can be controlled at about 30 ° to enlarge the volume of spinal canal effectively.It is feasible to use the formula to predict the size of the mini titanium plate before operation,and the appropriate size of the centerpiece titanium plate can be selected according to the estimated increase of the cross-sectional area of the spinal canal.However,the method of predicting the change of sagittal diameter of spinal canal needs to be improved and studied.