镍钛记忆合金舟大小融合器的研制及生物力学测试

Development and biomechanical study of NITI shape memory alloy STT arthrodesis device

目的探讨一种腕舟、大、小多角骨融合术内固定器械的研制和生物力学测试。方法根据国人腕舟状骨、大多角骨及小多角骨的解剖学参数测量和统计分析,采用镍钛记忆合金制作镍钛记忆合金舟大小融合器(NiTi shape memory alloy STT arthrodesis concentrator,NT-STTAC);取24侧成人上肢标本,分成NT-STTAC固定组和克氏针固定组,体外模拟腕舟状骨和大、小多角骨融合术,用858型双轴液压材料测试系统(858-MTS)测试其固定强度;大、中、小三型号的NT-SITAC各2件施加19.6～196.0 N的循环拉伸负荷(1 Hz),观察NT-STTAC的形变情况;分析实验结果,评价NT-STTAC的生物力学特性。结果NT-STTAC固定组的固定强度大于克氏针固定组(P<0.05);6件三型号NT-SITAC发生形变达6%时,施加的载荷次数分别为3 012、3 228、3 356、3 678、3 424和3 986次。NT- STTAC三固定臂产生的回复力可将舟状骨和大、小多角骨有效地聚合于一体,其体部可遮挡植入上述3处腕骨间关节间隙的松质骨,防止其滑脱。结论NT-STTAC的设计符合国人舟状骨和大、小多角骨的解剖学特点,其固定强度可满足腕舟、大、小多角骨融合术后无需外固定及早期功能锻炼的生物力学要求,疲劳强度可满足腕舟、大、小多角骨融合后达骨性愈合的需要。

Objective To develop a new internal fixator and method for STT arthrodesis. Methods According to the acquired measurements and anatomic features of the three carpal bones（scaphoid, trapezoid and trapezium） in Chinese population, a special internal fixator-NITI shape memory alloy STT arthrodesis concentrator （NT-STTAC） was designed. Twenty-four adult cadaver upper limb specimens were used and divided into NT- STTAC fusion group and K-wire fusion group. Simulation of STT arthrodesis was done in those specimens using different fixation device according to group assignment. Fixation strength was tested by a hydrolic pressure biomechanical system MTS-858. Six NT-STTACs were fatigued with 19.6 N to 196.0 N cycling pulling load （ 1 HZ） delivered by MTS-858 and deformation of the devices was carefully observed. Finally, the biomechanical features of NT-STTAC were evaluated according to the tested data. Results The fixation strength was stronger in NT-STTAC group than in Kirschner wire group （ P 〈 0.05）. When the 6 NT-STTAC were deformed to 6% by pulling load, they had resisted the pulling load for 3012, 3228, 3356, 3678, 3424 and 3986 respectively. The three carpal bones could be fused by the restored force that was generated by the fixed ann of NT-STTAC. The implanted cancellous bones in the intercarpal joint could be hold in place by the body of NT-STTAC. Conclusion The design of NT-STTAC is in accordance with the anatomical features of the three carpal bones. Its biomechanical strength allows early movement. The range of fatigue strength covers the period for bony fusion.