退变性第4腰椎椎体滑脱治疗中精确预弯钛棒的可行性分析

Feasibility of bending the titanium rod precisely in treating L4 degenerative spondylolisthesis

目的:用钉-棒内固定系统治疗退变性腰椎滑脱时,术中反复折棒会降低钛棒抗疲劳性并延长手术时间。分析折棒的影响因素并依据术前影像学显示的腰前凸角、滑脱角和滑移百分比探讨精确预折弯钛棒的可行性。方法:选择2006-02/09新疆自治区中医医院脊柱外科病房收治的31例Ⅰ度、Ⅱ度(Meyerding分度)退变性L4椎体滑脱需手术治疗的患者,均为女性,年龄40～70岁,平均58.3岁。测量术前腰前凸角、滑脱角和滑移百分比,术中置入依据相应标准折弯的钛棒,将研究对象假想为刚体,建立应变量(折棒角)与自变量(腰前凸角、滑脱角、滑移百分比)的多元线性回归方程,对各变量进行统计学分析与评价。数据的统计分析用SPSS13.0软件包处理结果:31例均进入结果分析。折棒角度与腰前凸角、滑脱角及椎体滑移百分比有相关性,多元线性回归方程:Y(折棒角)=0.1390-0.32756logx1(术前腰前凸角)+0.463689x2(术前滑脱角)+0.288186x32(术前滑移百分比),经方差分析方程有统计学意义(F=7.708,P=0.001)。常数0.1390有统计学意义(P=0.000477),x1的回归系数-0.32756有统计学意义(P=0.028383),x2的回归系数0.463689有统计学意义(P=0.003096),x3的回归系数0.288186有统计学意义(P=0.047435),决定系数R2=0.704257。结论:折棒角与腰前凸角、滑脱角、滑移百分比有相关性,折棒角变化的70.43%可由术前腰前凸角、滑脱角和滑移百分比来解释。术前将钛棒预弯成较精确的弯度,从而减小钛棒损耗是可行的。

AIM： When the rod internal fixation system is used for degenerative spondylolisthesis, titanium rod is usually repetitively bended during the operation, and accordingly the anti-fatigue of titanium rod would be decreased and the operative duration prolonged. In this study, the influential factors for rod bending and the feasibility to precisely bend the rod were investigated based on the angle of lumbar lordosis, slipping angle and percent of slip. METHODS： Thirty-one female patients with L4 degenerative spondylolisthesis （grade Ⅰ and Ⅱ Meyerding system）, who were treated by Department of Spinal Surgery, Affiliated Hospital of Traditional Chinese Medicine of Xinjiang Medical University, were selected from February to September 2006. They were aged 58.3 years （range, 40-70 years）. The angle of lumbar lordosis, slipping angle and percent of slip were measured respectively before operation. The bended titanium-rod based on the corresponding standards was inserted. The L4 lumbar vertebra was supposed as the rigid body to establish the multiple linear regression between the dependent variable （the angle of bending rod） and independent variable （the angle of lumbar lordosis, slipping angle and percent of slip）. The variables were analyzed and evaluated statistically. Data analysis was performed with SPSS 13.0 software. RESULTS： All 31 subjects were involved in the result analysis. There was correlation between angle of bending rod and the angle of lumbar lordosis, slipping angle and percent of slip. The multiple linear regression equation was： Y （the angle of bending rod） =0.139 0-0.327 56 log x1 （the angle of lumbar lordosis） ＋ 0.463 689x2 （the slipping angle） ＋ 0.288 186x32 （percent of slip）. There were statistically significances （F =7.708, P =0.001）. Constant 0.139 0 was statistically significant （P =0.000 477）, so was the regression coefficient of xl： 0.327 56 （P =0.028 383）, the regression coefficient of x2：0.463 689 （P =0.003 096）, and the regression coefficient of x3：0.288 186 （P =0.047 435）. Coefficient of determination： R^2 =0.704 257. CONCLUSION. There is correlation between angle of bending rod and the angle of lumbar lordosis, slipping angle and percent of slip.70.43% of the changes in angle of bending rod could be explained by the angle of lumbar lordosis, slipping angle and percent of slip. It is possible to preliminarily bend the rod precisely in a relative way before the operation to diminish the strain of titanium rod.