三种固定器械置入固定胫骨骨折的生物力学分析☆

背景：胫骨骨折后以胫骨骨折髓内钉、钢板内固定和外固定支架固定后骨折断端的轴向压缩、弯曲、扭转力将发生怎样的变化？ 目的：对比观察胫骨轴向控制髓内钉，胫骨接骨钢板及胫骨外固定支架3种内外固定器械置入固定胫骨骨折的生物力学特性。 设计、时间及地点：观察性实验，于2007-08在吉林大学力学实验中心完成。 材料：新鲜胫骨标本9对，由白求恩医科大学解剖教研室提供；夹具由吉林大学力学实验中心提供；胫骨轴向控制髓内钉为上海浦卫医疗器械厂产品；胫骨接骨板(钢板)为常州华森医疗器械有限公司产品；胫骨外固定支架为常州市康辉医疗器械有限公司产品。 方法：9对新鲜尸体胫骨，随机分为髓内钉组，接骨板组和外固定支架组，每组3对。以线锯在胫骨中段锯开，制成DAT分类A1型骨折模型，分别以胫骨轴向控制髓内锁钉、钢板、外固定支架固定标本，在电子万能试验机上对3组标本进行轴向压缩实验和弯曲实验，在扭转试验机上进行扭转实验。 主要观察指标：标本承受轴向压缩、弯曲载荷时的位移值和在转矩作用下扭转角度。 结果：髓内钉组轴向压缩，弯曲位移小于接骨板组和外固定支架组，但差异无显著性意义(P > 0.05)，髓内钉固定组扭转角度小于接骨板组和外固定支架组，差异有显著性意义(P < 0.05)。 结论：髓内钉内固定胫骨骨折组标本抗弯、抗扭、抗轴向压缩能力强，具有较好的力学特性。钢板固定组和外固定支架组抗弯和抗轴压缩能力也较强，虽抗扭转能力不如髓内钉组，但也具有较好的力学特性。

Biomechanical analysis of tibial fracture fixed by three fixation devices

BACKGROUND: It is necessary to understand the axial compression, bending, torque changes after fixation by intramedullary nailing of tibial fracture, plate fixation and external fixation. OBJECTIVE: To explore the biomechanical properties of three internal and external fixation devices (intramedullary nails, steel and the external fixator) for tibial fractures. DESIGN, TIME AND SETTING: Observation. The study was performed at the Mechanical Laboratory Center of Jilin University in August 2007. MATERIALS: A total of 9 samples of fresh tibia were provided by Norman Bethune University of Medical Science; fixture was provided by the Mechanical Laboratory Center of Jilin University; tibial axial intramedullary nail was purchased from Shanghai Puwei Medical Instrument; steel plate from Changzhou Waston Company; external fixator was purchased from Changzhou Kanghui Medical Instrument Company. METHODS: The fresh samples were randomly divided into intramedullary nails, steel plate and external fixator groups (n=3). The middle tibia was saw to make model of type A1 fracture according to DAT classification and fixed respectively by intramedullary nails, steel plate and external fixator. Three sets of specimens were subjected to compressed axial compression test and bending experiments in the electronic universal testing machine, and to torsion experiment in the torsion test machine. MAIN OUTCOME MEASURES: Displacement of samples under axial compression and bending loading as well as torsion angle under torsional moment. RESULTS: The intramedullary nail group exhibited less displacement of under axial compression and bending loading than the other groups, but the difference was not significant (P > 0.05); while torsion angle of intramedullary nail group was significantly less than the plate and external fixator groups (P < 0.05). CONCLUSION: The intramedullary nail fixation for tibial fracture displayed bending, torsion, axial compression resistance abilities and good mechanical properties. Plate fixation and external fixation also have strong anti-bending ability and axial compression resistance. Although their anti-torsion effect is inferior to intramedullary nail, they have good mechanical properties.