胫骨中段骨折钢板固定螺钉位置的生物力学研究

Biomechanics Study of the Position of Screw for Plate Internal Fixation of Tibial Shaft Fracture

[目的]研究胫骨中段骨折用钢板螺钉内固定时螺钉位置对骨折生物力学影响.[方法]选取新鲜成人（20～40岁）尸体胫骨标本60根,长度30～38 cm,平均34 cm.随机分成4组,每组15根,分别作以下三种状态下的试验.测定完整的新鲜人胫骨在扭转、三点弯曲、压缩等状态下的应力-应变指标,确定垂直压缩应力为0～1 000 N,扭转角度为0～3°,三点弯应力为0～400 N.然后制成中段斜行无缺损骨折模型,通过14孔钢板,使用相同数量螺钉（6枚）,不同位置（A组固定自上而下1,2,7,8,13,14孔.B组固定自上而下1,4,7,8,11,14孔.C组固定自上而下1,3,6,9,12,14孔.D组固定自上而下1,2,3,12,13,14孔）螺钉固定,分别进行三种状态的生物力学测试,进行统计学分析.[结果]四组垂直压缩时竖直方向应变值分别为0.120±0.006、0.0330±0.0027、0.139±0.005、0.116±0.008,B组和其他组对比差异有统计学意义（P〈0.01）.四组侧方应变值分别为0.234±0.007、0.237±0.0006、0.187±0.002、0.217±0.002,C组和其他组比较差异有统计学意义（P〈0.01）.四组扭矩分别为（7.304×10-3±3.072×10-3）N·m、（6.965×10-3±3.096×10-3）N·m、（4.570×10-3±2.228×10-3）N·m、（2.086×10-3±0.998×10-3）N·m,C组和其他组比较差异有统计学意义（P〈0.01）.三点弯曲竖直方向应变值分别为0.149±0.098、0.184±0.002、0.004±0.001、0.282±0.000,A、B组和其他组两两比较差异均有统计学意义（P〈0.01）,D组和其他组两两比较差异均有统计学意义（P〈0.01）,A、B组两两比较差异无统计学意义（P〉0.05）.[结论]使用相同材质、相同长度、相同宽度、相同数量螺钉,靠近骨折线处上螺钉,抗压缩稳定性和抗扭转稳定性较好,而螺钉分布于钢板两端,抗扭转稳定性较差.螺钉平均分布,抗弯曲稳定性和抗扭转稳定较好,而螺钉分布于钢板两端,抗弯曲、抗压缩、抗扭转稳定性较差.

[Objective] To investigate the effect of the position of the screw in plate and screw internal fixation for the treatment of tibial shaft fracture on bone biomechanics. [Methods] Sixty fresh tibia specimens of adult cadaver（20-40 years old） with the length of 30-38cm（average 34cm） were selected and randomly divided into 4 groups with 15 in each for experiments under three conditions, respectively. The stress-strain indexes of whole fresh tibia under the reverse, three-spot curve and compression were measured. The vertical elastic stress was 0-1000 N, and the reverse angle was 0-3°, and three-spot curve stress was 0-400 N. Then the middle oblique non-defect bone fracture model was made. The fractures were fixed by 14- hole steel plates and screws（ n =6） at different position including 1, 2, 7, 8, 13 and 14th hole （group A）, 1, 4, 7, 8, 11 and 14th hole（group B）＇, 1, 3, 6, 9, 12 and 14th hole（group C）, and 1, 2, 3, 12, 13 and 14th hole（group D） from up to down. The biomechanics under three conditions were measured respectively, and statistical analysis was done. [Results] The strain values in the erect direction of vertical compression in 4 groups were 0. 120±0. 006, 0. 0330±0. 0027, 0. 139±0. 005 and 0, 116±0. 008, respectively, and there was statistical significance between group B and the other groups（ P〈0.01）. The strain values at the side in 4 groups were 0. 234±0. 007, 0. 237±0. 0006, 0. 187±0. 002 and 0. 217±0. 002, respectively, and there was statistical significance between group C and the other groups（ P〈0.01）. The torque of 4 groups were（7.304×10-3±3.072×10-3）N·m、（6.965×10-3±3.096×10-3）N·m、（4.570×10-3±2.228×10-3）N·m、（2.086×10-3±0.998×10-3）N·m,, respectively, and there was statistical significance between group C and the other groups（ P〈0.01）. The strain values in the erect direction at three-spot curve of 4 groups were 0. 149±0. 098, 0. 184±0. 002, 0. 004±0. 001 and 0. 282±0. 000, respectively, and there was statistical significance between group A or group B and the other groups（ P〈0.01）, and there was also statistical significance between group D and the other groups（ P〉0.05）, but there was no statistical significance between group A and group B（ P〉0.05）. [Conclusion] The anti-compression stability and anti-reverse stability of screws with same material, length, width and quantity and near to fracture line is good, while the anti-reverse stability of the screws distributed in both ends of steel plate is bad. When the screws distribute evenly, the anti-curving and anti-reverse stability are good. When the screws distribute in both ends of steel plate, the anti-curving, anti-compression and anti-reverse stability are bad.