异体皮质骨板不同固定方式的生物力学比较

背景:同种异体骨内固定材料已用于临床,但因为强度小仅用于应力较小的部位,如何提高其固定的强度以扩大应用范围是目前研究的关键.目的:探讨同种异体皮质骨板采用不同固定方式的强度差异及机制.设计、时间及地点:体外生物力学实验,于2005-10/2006-03在南华大学生物力学实验室完成.材料:防腐尸体上取下股骨27根;同种异体骨板制备成110mm×10mm×3衄的骨板45块;骨螺钉90个.方法:27根股骨制作骨折模型,分为双骨板嵌合组、双骨板骨螺钉组、单骨板骨螺钉组,9个,组.双骨板嵌合组:用2块大小为110 mm×10 mm×3 mm同种异体皮质骨板嵌合固定.双骨板骨螺钉组:用2块110 mm×10 mm×3 mm同种异体皮质骨板和5枚骨螺钉固定.单骨板骨螺钉组:用1块110mm×10mm×3mm骨板和5枚骨螺钉固定.主要观察指标:分别对以上3组进行生物力学实验,测试其压缩、弯曲及扭转刚度和极限载荷.结果:不同固定方式显示不同的力学特征,双骨板嵌合组的抗压刚度与双骨板骨螺钉组相似,高于单骨板骨螺钉组,但抗弯和抗扭刚度显著高于后两组,差异有统计学意义(P＜0.05).双骨板嵌合组压缩、弯曲、扭转极限载荷大于双骨板骨螺钉组(P＜0.05),显著大于单骨板骨螺钉组(P＜0.01).结论:同种异体皮质骨板固定的强度与固定方式有关.双板嵌合固定比骨板骨螺钉固定具强度和刚度更大,可满足临床需要.

Biomechanics of cortical bone allografts among different fixation modes

BACKGROUND:The materials for internal fixation of bone allografts have been used in the clinic.However,they are only used in the regions bearing little stress because of low strength.The focus of current studies is how to enhance the fixation strength of the materials to expand application range.OBJECTIVE:To compare the strength difference of cortical bone allografts among different fixation modes and to investigate the possible mechanisms of action.DESIGN,TIME AND SETTING:An in vitro biomechanical experiment was performed at the Laboratory of Biomechanics,Nanhua University between October 2005 and March 2006.MATERIALS:Twenty-seven pieces of cadaveric femurs were included in this study.A total of 45 cortical bone allografts with a size of 110 mm×10 mm×3 mm and 90 bone screws were also used.METHODS:Twenty-seven femurs were made into simulated fracture models and randomized to 3 groups,with 9 models per group:A,B,and C.In the group A,the models were fixed with two cortical bone all6grafts; the models from the groups B and C were fixed with two bone allografts plus 5 bone screws and one bone allograft plus 5 bone screws accordingly.MAIN OUTCOME MEASURES:Biomechanical tests were performed in the above-mentioned 3 groups to measure compressive,bending and torsional stiffness as well as the maximum loads.RESULTS:Different fixation models displayed different mechanical characteristics.The group A exhibited similar compressive stiffness compared to the group B,but the level was significantly higher compared to the group C (P ＜ 0.05).The other two stiffness parameters including bending and torsion were significantly greater in the group A than in the groups B and C (P ＜ 0.05).The maximum loads of compression,bending,and torsion were significantly greater in the group A compared to the group B (P ＜ 0.05) and group C (P ＜ 0.01).CONCLUSION:The strength of bone allograft is highly related to fixation mode. The two bone allografts showed greater strength and stiffness than struts fixed with bone screws,which meet the clinical requirements.