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。