单侧纵轴动力外固定器治疗胫腓骨骨折致骨延迟愈合的生物力学研究与临床

Biomechanical Study on Delayed Union of Tibia and Fibula Fracture Treated With Unilateral Axial Dynamic Fixator

目的 通过对单侧纵轴动力外固定器（ｕｎｉｌａｔｅｒａｌａｘｉａｌｄｙｎａｍｉｃｆｉｘａｔｏｒ，ＵＡＤＦ） 的力学测试，分析引起骨折延迟愈合的机制。方法 对用ＵＡＤＦ固定的胫骨骨折模型进行加载实验。设置不同的骨－ 架间距，施加不同的载荷，测定骨折端的位移值。结合临床病例对发生骨折延迟愈合的病因进行生物力学的分析。结果骨折端位移与骨－ 架间距以及施加载荷的大小呈正相关（ｒ１ ＝ ０．６１０ ４，ｒ ２ ＝ ０．７０９ ２，Ｐ ＜ ０．０１），差异有显著性意义。４８ 例骨折延迟愈合中，骨折愈合时间最短７ 个月，最长１５ 个月。因技术失误导致外固定架高刚度固定作用失效者１８ 例；外固定架的高强度特性，误导患者过早负重导致骨折延迟愈合１０ 例；１２ 例忽视了创造骨折端稳定界面对外固定架高刚度固定的重要性； 另外有８ 例只注重于高刚度固定， 而忽视了向弹性固定的转换，由此而发生了骨折的延迟愈合。结论 生物力学是骨折愈合的极其重要因素，使用ＵＡＤＦ发生的骨折延迟愈合，常是多种因素同时存在所致，如：骨－ 架间距的大小、负重载荷超限、骨折端的不相接触或缺损所致的极度不稳定界面以及固定器的高刚度固定维持时间过长等，共同干扰骨折的正常愈合。

Objective To analyze the possible factors leading delayed fracture union with the mechanical testing of unilateral axial dynamic fixator (UADF). Methods Mechanical loading was applied to the tibia fracture model fixed with UADF. Movement between fragments with different loadings and different bone frame distance was measured. The factors of delayed union in 48 cases were analysed. Results The movement between fragments correlated well with the bone frame distance and the amount of loading (r 1=0.610 4, r 2=0.709 2,P< 0.01). In the 48 cases of delayed union, the longest healing time was 15 months, while the shortest was 7 months. Several factors were related to the delayed union. The lose of stiffness of external fixator due to technical error was found in 18 cases; too early mobilization in 10 cases; instability between fragments in 12 cases; and negligence of the translation of high stiffness to the elasticity of the fixator in 8. Conclusion Several factors were releated to the delayed union with UADF, which including the distance between bone and frame, loading applied to the fixator, inadequate contact of fragments, as well as prolonged fixation with high stiffness.