新型镍钛记忆合金掌指关节假体的生物力学研究

目的 探讨新型镍钛（Ni-Ti）记忆合金掌指关节假体的轴向压缩刚度特征,为该假体的临床应用提供生物力学依据。方法 选用10侧完整成人新鲜手标本,按数字表法随机分为假体组和对照组,每组5侧。假体组分别在第2~5掌指关节置入新型Ni-Ti记忆合金掌指关节假体,对照组标本只做切开及缝合处理。假体组和对照组手标本分别解剖游离出第2~5掌指关节,分别以伸直位、屈曲30°、屈曲60°固定于BOSE材料试验机上,分别在载荷为50、100、150、200、250、300、350 N时记录标本的轴向压缩位移,计算垂直和屈曲载荷状态下的轴向压缩刚度。所有标本实验后使用X线机透视,观察有无骨折,有无假体松动、断裂等情况。在假体组和对照组的组内和组间,分别比较第2~5指掌指关节在伸直位和屈曲30°、60°位时轴向压缩刚度。结果 所有标本实验后X线机透视检查显示,无明显骨折,假体无松动、断裂等情况。假体组和对照组第2~5掌指关节的轴向压缩刚度均随着掌指关节屈曲角度的增大而逐渐减小。假体组与对照组比较,第2~5指掌指关节伸直位时轴向压缩刚度差异均无统计学意义（P值均>0.05）;屈曲30°、60°时假体组轴向压缩刚度均大于对照组,差异均有统计学意义（P值均<0.05）。假体组和对照组组内比较,在伸直位和屈曲30°、60°位时,不同掌指关节间轴向压缩刚度差异均无统计学意义（P值均>0.05）。结论 新型Ni-Ti记忆合金掌指关节假体轴向压缩刚度符合正常掌指关节的生物力学特征。置入该假体后,不同掌指关节在不同屈曲角度下均具有良好的稳定性。

Biomechanical study of a new Ni-Ti memory alloy metacarpophalangeal joint prosthesis

Objective To investigate the axial compression stiffness characteristics of a new Ni-Ti memory alloy metacarpophalangeal joint prosthesis and provide a biomechanical basis for its clinical application.Methods Ten intact adult fresh hand specimens were randomly divided into prosthesis and control groups in accordance with the number table method, with each group having five sides. The new Ni-Ti memory alloy metacarpophalangeal joint prosthesis was implanted in the 2nd to 5th metacarpophalangeal joints in the prosthesis group, whereas the specimens in the control group were only treated with incision and suture. The 2nd to 5th metacarpophalangeal joints were dissected from the prosthesis and control groups and fixed on a BOSE material testing machine in the extension position, 30° flexion, and 60° flexion. Then, the axial compression displacement of each specimen was recorded when the load was 50, 100, 150, 200, 250, and 300 N. The axial compression stiffness under vertical load was calculated. The occurrence of fracture, loosening, or breakage of the prosthesis was determined via X-ray after the experiment. The axial compression stiffness of the 2nd to 5th metacarpophalangeal joints at the extension position and flexion positions of 30° and 60° were compared, respectively, within and between groups.Results No obvious fracture was observed in all the specimens, and no loosening or breakage of the prosthesis occurred after the experiment with X-ray. The axial compression stiffness of the different metacarpophalangeal joints decreased gradually with the increase in the flexion angle of the metacarpophalangeal joints in the prosthesis and control groups. Between the prosthesis and control groups, no significant difference in the axial compression stiffness of the 2nd to 5th metacarpophalangeal joints was observed in the extended position (all P values > 0.05). The axial compression stiffness of the prosthesis group was greater than that of the control group at 30° and 60° flexion, and the differences were statistically significant (all P values < 0.05). Moreover, no significant difference in the axial compression stiffness of the different metacarpophalangeal joints was observed at extension and flexion positions of 30° and 60° in the two groups (all P values > 0.05).Conclusion The axial compression stiffness of the specimen implanted with the new Ni-Ti memory alloy metacarpophalangeal joint prosthesis is consistent with that of the normal metacarpophalangeal joint. The prosthesis demonstrates good stability under the different flexion angles.