To measure the angle which composed of terminal plates of C2/3 to C7/T1, added the angle of procurvation and retroflexion each segment to get the extension of the intervertebral space and compare the change with them.

• 角度测量是自C2/3至C7/T1逐个节段测量其终板所成夹角，前曲与后伸位测得的夹角相加得出单个节段椎间隙活动范围，比较手术前、后角度变化。