新型经皮椎弓根螺钉系统的设计与生物力学测试

The designs and feasibility of clinical applications about a novel percutaneous pedicle screw system

目的 评估新型经皮椎弓根螺钉系统设计的合理性和临床操作可行性.方法 取6具经甲醛处理的完整尸体标本,模拟临床手术操作安放新型经皮椎弓根螺钉系统（A组）,以传统经皮椎弓根螺钉系统为对照（B组）.应用新型经皮椎弓根螺钉系统在新鲜小牛腰椎压缩性骨折模型上行撑开操作.分别以单向螺钉、改良螺钉和万向螺钉跨节段固定骨折,测量固定节段的三维稳定性.结果 A组平均手术时间（38.2±6.20）min,B组（56.4±12.8）min,差异有统计学意义（P〈0.05）.A组螺钉位置优良率91.7%,B组95.8%,差异无统计学意义.新型椎弓根螺钉系统对三种螺钉均具有良好的撑开功能,改良螺钉和单向螺钉主要撑开椎体前柱,两者差异无统计学意义;万向螺钉主要撑开椎体中、后柱,对前柱撑开效果较其他两种螺钉差（P〈0.05）.三组固定节段在完整状态和骨折状态的屈伸、左右侧弯及旋转运动范围无统计学差异.改良螺钉和单向螺钉固定后固定节段有相似的三维稳定性;万向螺钉屈伸稳定性较改良螺钉差（P〈0.05）,而侧弯和旋转稳定性与其他两组接近.结论 改良螺钉能有效撑开椎体前柱,螺钉-棒系统可对固定节段提供稳定性.新型经皮椎弓根螺钉系统具有临床操作可行性.

Objective To evaluate the rationality of the designs and the feasibility of applications about a novel percutaneous pedicle screw system. Methods Six human cadaver specimens were used to simulate operative procedures with the novel percutaneous pedicle screw system （group A）, and Sextant sys-tem was served as a control group （group B）. Compression fractured vertebral bodies harvested from fresh calf were distracted with novel percutaneous pedicle screw system to assess the distraction function of percuta-neous system and distraction effect of modified screw. Biomechanical properties of modified screw were as-sessed according to the fixation effects of three types of screw-rod systems for fractured segment. Results The mean operation time in group A [（38.2 6.20） min] and B [（56.4 12.8） min] had significant difference （P〈 0.05）. The excellent and good rate of screws position was 91.7% and 95.8% in group A and B, respectively, showed no significant difference. The novel percutaneous system had a good distraction function to three kinds of screws. Modified and monoaxial screws could distract mainly the anterior column of vertebral body and there was no significant difference. However, the polyaxial screws distracted mainly middle and posterior column, the distraction effect of the anterior column was not as good as previous screws （P〈0.05）. There were no significant differences in flexion and extension, lateral bending and rotation of all specimens in intact and fractured. Modified and monoaxial screws could provide similar three-dimensional stabilities to fractured specimens. Polyaxial screw provided poor stability in flexion and extension compared with the two previous of screws （P〈0.05）. There were no significant differences in lateral and rotation stability provided by three kinds of screws. Conclusion Through using novel percutaneous pedicle screw system, modified and monoaxial screws have similar distraction effect on anterior column of vertebral body, and can provide similar three-dimen-sional stability. The novel percutaneous pedicle screw system is well-designed and feasible in clinical practice.