一种改良椎弓根螺钉的设计和生物力学研究

Designs and Biomechanical Study of a Modified Pedicle Screw

目的评估新型椎弓根螺钉撑开效果和生物力学稳定性,为后期临床应用提供依据。方法应用新型椎弓根螺钉在新鲜小牛腰椎压缩性骨折模型上进行撑开操作,评估新型螺钉的撑开效果。将新型椎弓根螺钉跨节段固定小牛腰椎压缩性骨折模型上,评估新型螺钉-棒系统的生物力学稳定性。结果新型椎弓根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(P>0.05)。而万向螺钉主要撑开的椎体中、后柱,对前柱撑开效果不如前两种螺钉明显,差异有统计学意义(P<0.05)。新型椎弓根螺钉和单向螺钉对固定节段具有相似三维稳定性,两者差异无统计学意义(P>0.05)。万向螺钉屈伸稳定性比新型螺钉或单向螺钉差,差异有统计学意义(P<0.05);三种螺钉得侧弯稳定性相似,差异无统计学意义(P>0.05);万向螺钉旋转稳定性比改良螺钉与单向螺钉稍强,但差异无统计学意义(P>0.05)。结论新型椎弓根螺钉设计合理,可以有效地撑开骨折椎体前柱,新型螺钉-棒系统对固定节段可以提供有效稳定性,具有较好的临床应用前景。

Objective To evaluate the reasonableness of the designs and the stability of a novel pedicle screw,and provide a basis for the late clinical applications.Methods Compression fractured vertebral models were distracted with three kinds of screws in order to as-sess the distraction effect of modified screw.Biomechanical stabilities of modified screw were assessed according to the fixed effect of three types of screw-rod systems providing fractured segments.Results Modified screws and monoaxial screw applied could distract mainly the anterior column of vertebral body and there was no significant difference（P 0.05）.However,the polyaxial screws applied distracted main-ly posterior column of the vertebral body,the distraction effect of the anterior column was not good as previous screws,and there was sig-nificant difference（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 monaxial screws could provide similar three-dimensional stability to fractured specimens,and there was no significant difference（P 0.05）.Polyaxial screw provided poorly stability in flexion and extension compared with previous two screws,and there was significant difference（P 0.05）.The lateral stability provided by three kinds screws was similar and rotation stability was im-proved slightly in polyaxial screw relative to other two screws,however,there were no significant differences（P 0.05）.Conclusion Modi-fied screw is well-designed and could effectively distract anterior column of vertebral body.Modified screw-rod system could provide ex-cellent three-dimensional stabilities to fixated segment,with wide application prospects.