聚醚醚酮(PEEK)棒用于羊颈椎固定的生物力学评价

Biomechanical analysis on PEEK rods in cadaveric sheep cervical spine

[目的]评估直径3.2 mm PEEK棒应用于羊颈椎固定的生物力学稳定性,对比PEEK棒与传统钛合金棒固定的生物力学特点。[方法]取6具新鲜羊C_(3、4)椎体标本,通过非损伤性加载方式分别对完整标本、失稳标本、PEEK棒固定标本、钛合金棒固定标本进行生物力学测试。记录在垂直压缩方向的压缩位移及刚度、椎体前缘微应变,以及前屈、后伸、左右侧弯四个方向的移动度。[结果]PEEK棒固定组和钛合金棒固定组各方向移动度均较完整组减小(P<0.05),在左右侧弯方向,PEEK棒固定组移动度大于钛合金棒组(P<0.05)。轴向压缩实验显示,两种固定后较完整组刚度均有显著增加(P<0.05),PEEK棒固定组刚度小于钛合金棒固定组(P<0.05)。颈椎前缘应变结果显示,钛合金棒固定组椎体前缘应变显著低于完整组及PEEK棒固定组(P<0.05),PEEK棒固定组应变与完整组未见显著差异。[结论]直径3.2 mm的PEEK棒可以满足离体羊颈椎即刻生物力学稳定的要求,其较钛合金棒固定增加了椎间应力,有利于促进骨性融合。

[Objective] To evaluate the biomechanical characteristics of polyetheretherketone （PEEK） rods of 3.2 mm in di- ameter for cervical spine by comparing with the traditional titanium alloy rods. [Methods] Six fresh cadaveric sheep cervical spines （C3~C4） were used for this study. After intact specimens had been tested, partial facetectomy was performed on the spine to create a destabilized model. Subsequently, the destabilized spines were instrumented with PEEK rods or Titanium alloy rods randomly. Nondestructive biomechanical testing was conducted on each specimen to evaluate the axial displacement, axial rigid- ity, micro-strain of anterior vertebral body and intervertebral range of motion （ROM） in flexion, extension as well as lateral bend- ing. [Results] The ROMs in both the PEEK group and titanium group were significantly less than that of the intact group （P〈 0.05）, while the ROM in the PEEK group was greater than the titanium groups in lateral bending （P〈0.05）. In addition, the axi- al compression rigidity of the PEEK group and titanium group was significantly higher than that of the intact group （P〈0.05）, whereas the rigidity of the PEEK group was significantly less than that of the titanium group （P〈0.05）. In term of micro-strain in C3. the PEEK group and the intact group were significantly superior to the titanium group （P〈0.05）, despite the fact that no significant difference was noted between the PEEK group and the intact group （P〉0.05）. [Conclusion] The PEEK rod of 3.2ram in diameter does provide enough biomechanical stability for sheep cervical spine, associated with increased intervertebral com- pression stress over the titanium rod, which has potential to promote intervertebral fusion.