基于椎弓根螺钉的新型聚醚醚酮树脂动态稳定内固定系统的生物力学评价

Biomechanical evaluation of pedicle screw-based polyetheretherketone dynamic stabilization system

目的 评价一种丝于椎弓根螺钉的新型聚醚醚酮树脂（PEEK）动态稳定内固定系统的生物力学特性。方法将骼套测试装置加载于试验机上进行静态测试（压弯、拉伸和扭转）和疲劳测试。静态压缩弯曲与拉伸弯曲试验采用位移控制加载．以25mm／min速率将内固定系统压或拉至破坏：静态扭转试验采用扭转角度控制加载，以60°／min的速率将结构物扭转至极限状态。疲劳试验采用载简控制的眶弯疲劳加载．加载的波形为正弦波，加载频率为5Hz，载荷比为10，循环极限次数为500万次。结果PEEK动态稳定内固定系统静态压缩弯曲2％变形位移为1．52mm，弹性位移为（6．39±1．80）mm，屈服载荷为（1505．86±189．17）N，压弯刚度为（236．16±59．64）N／toni，极限载荷为（1649．05±206．46）N；静态拉仲弯曲2％变形位移为1．52nml，弹性位移为（24．86±5．71）mm，屈服载荷为（2041．50±605．80）N，拉弯刚度为（28．70±7．47）N／mm，极限载荷（2424．51±625．82）N；静态扭转2％变形细化移为1．95°，弹性角位移为8．73°±3．69°，屈服扭矩为（6．48±1．93）N·in，扭转刚度为（0．73±0．20）N／mm，极限扭矩为（9．31±1．12）N·m。脊柱内固定系统疲劳极限载荷参考值为1000N、结论PEEK动态稳定内崮定系统具有较好的动态稳定性，且能保留固定节段活动度。

Objective To clarit biomechanical eharacteristics of the pedicle screw-based polyetheretherketone （PEEK） dynamic stal）ilization system. Methods Mechanical tests were performed fol- lowing tile guideline of ASTM FI 717-04 In determine the mechanical characteristics of the 6, 35 mm PEEK rod under stalic and dynamic hladiug conditinn Static cnmpressinn l）ending tests were conducted in the ElectroForce~ 3510 instrument and in displacement control at a rate of 25 mm/min until failure occurred; tailure was defined as either fractnren｜＇allimplantoranoticeab]ereductioninstiffness, ix）ad and displacement data were collected. Statietnrsion tests were conducted in the same machine and under rotation control at a rate of 1 degree/s until a rotational dis- placement of 30 degrees was reached or failure occurred. Torque and rotation data were again eollectecL Dynamic compression tests were perfornmd in sinusoidal displacement control using an R ratio equal to lO, and at a maximum fl＇eqnency of 5 Hz and in ambient conditions. Each specimen was dynamically loaded until fracture of the implant urred or 5 million cycles had occurred. Results The static compression bending tests showed that the mean aud standard （leviatinn of the displacement at 2% offset was 1.52 mm, elastic displacement 6.39 -± 1.80 ram, compressive bending yiehl load 1505.86 ± 189. 17 N, compressive bending stiffness 236. 16 ± 59.64 N/ram, and compressive bending uhimate hlad 1649.05 ± 206.46 N. The static tension bending tests showed that the mean and standard deviation of the displacement at 2% offset was 1.52 ram, elastic displacement 24.86 ± 5.71 ram, tensile bending yiehl load 2041.50 ± 605.80 N, tensile bending stiffness 28.70 ± 7.47 N/ram, and tensile bending uhi- mate h）ad 2424.51 -± 625.82 N. The static torsional tests showed that the mean and standard deviation of the angular displacement at 2% offset was 1.95°, elastic angular displacement 8.73°±3. 69°, yield torque 6.48 ± 1.93 N · m, torsional stiffness O. 73 ±0.20 N/ram, and uhimate torque 9.31 ± 1. 12 N ·m The reference value for the en- durance uhimate load of the internal fixation of the spine was 1000 N. Conclusion The PPDS provides dynamic stal）ilily in case of instrument segments and preserves motion at the operative level.