椎弓根螺钉的不同结构特点对螺钉电阻的影响

Experimental study of the influence of different intrinsic properties of pedicle screws on the electrical resistance

中文关键词:  椎弓根螺钉  电阻  脊柱  直径  空心  实心

英文关键词:Pedicle screw  Electrical resistance  Spine  Diameter  Solid  Cannulated

中文摘要:

  【摘要】 目的：研究椎弓根螺钉的不同结构特点（实心与空心螺钉、直径）对螺钉电阻的影响，进而探讨其对刺激肌电监测椎弓根螺钉置入准确性的可能影响。方法：选择临床常用的两个厂家（强生和美敦力公司）的12枚椎弓根螺钉，每个厂家各6枚，强生公司实心与空心螺钉的直径均为5.0mm、6.0mm和7.0mm；美敦力公司实心与空心螺钉的直径均为4.5mm、5.5mm和6.5mm。用万用电表测量通过椎弓根螺钉的电流，用电位差计测量螺钉杆上间隔20mm节段的电位差，通过欧姆定律计算椎弓根螺钉的电阻值。结果：美敦力公司的4.5mm实心与空心椎弓根螺钉电阻分别为（0.142±0.003）Ω和（0.398±0.002）Ω，5.5mm实心与空心椎弓根螺钉电阻分别为（0.110±0.007）Ω和（0.347±0.003）Ω，6.5mm实心与空心椎弓根螺钉电阻分别为（0.086±0.002）Ω和（0.290±0.003）Ω。强生公司的5.0mm实心与空心椎弓根螺钉电阻分别为（0.149±0.001）Ω和（0.291±0.001）Ω，6.0mm实心与空心椎弓根螺钉电阻分别为（0.123±0.004)Ω和（0.237±0.001）Ω，7.0mm实心与空心椎弓根螺钉电阻分别为（0.095±0.001）Ω和（0.148±0.001）Ω。相同直径的空心椎弓根螺钉较实心椎弓根螺钉具有较大的电阻，差异有统计学意义（P<0.05）。无论实心椎弓根螺钉或空心椎弓根螺钉，随着直径的增大，椎弓根螺钉的电阻值逐渐减小，差异有统计学意义（P<0.05）。结论：长度与直径相同的空心椎弓根螺钉较实心螺钉具有较大的电阻，长度相同的实心或空心小直径椎弓根螺钉具有较大的电阻，应用刺激肌电监测椎弓根螺钉置入时要注意其带来的影响。

英文摘要:

  【Abstract】 Objectives: To study the influence of pedicle screw structural features(solid and cannulated pedicle screws, diameters) on the electrical resistance of pedicle screws and to discuss its possible effect on the accuracy of pedicle screw insertion monitored by stimulus-evoked electromyography. Methods: Electrical resistance measurements were obtained from 12 pedicle screw varieties(6 screws of each manufacturer: solid or cannulated pedicle screws with diameter of 5.0mm, 6.0mm, 7.0mm in Johnson company and solid or cannulated pedicle screws with diameter of 4.5mm, 5.5mm, 6.5mm in Medtronic company) across the screw shank with an interval of 20mm based on measured constant current and voltage using potentiometer and multimeter according to Ohm′s law. Results: Electrical resistance of pedicle screws with 4.5mm, 5.5mm, 6.5mm in diameter was (0.142±0.003)Ω, (0.110±0.007)Ω, (0.086±0.002)Ω in solid pedicle screws respectively and (0.398±0.002)Ω, (0.347±0.003)Ω, (0.290±0.003)Ω in cannulated pedicle screws respectively from Johnson company. Electrical resistance of pedicle screws with 5.0mm, 6.0mm, 7.0mm in diameter was (0.149±0.001)Ω, (0.123±0.004)Ω, (0.095±0.001)Ω in solid pedicle screws and (0.291±0.001)Ω, (0.237±0.001)Ω, (0.148±0.001)Ω in cannulated pedicle screws got from Medtronic company, and the electrical resistance of cannulated screws was much higher than that of solid screws in the same diameter group(P<0.05). The screw with largest diameter had lower electrical resistance than the screws with shorter diameters, whether solid screws or cannulated screws(P<0.05). Conclusions: Cannulated pedicle screws have higher electrical resistance compared to the solid pedicle screws with the same length and diameter, smaller diameter pedicle screws have higher electrical resistance compared to the larger diameter pedicle screws, we should pay much attention to its influence when stimulus-evoked electromyographic test was used in placing pedicle screw.