沿骨干轴线不同长度皮质骨缺损对骨干生物力学性能的影响

Influence of cortical bone defects of different lengths on biomechanics of long tubular bone

目的：皮质缺损的宽度和长度对骨干的生物力学强度均有影响，既往对缺损宽度的研究较多，对缺损长度的研究很少。实验拟验证皮质缺损长度对骨干生物力学性能的影响。方法：实验于2007-10/12在北京大学人民医院创伤骨科实验室完成。（1）实验材料：新鲜成年山羊股骨标本54个，纳入标准：①外观没有破损。②骨干最窄处冠状面直径范围在14～17mm之间，矢状面直径在14～17mm之间。骨干长度〉120mm。（2）实验方法：在骨干张力侧制作矩形单侧骨皮质缺损，缺损的宽度分别为骨干冠状面直径的10％和20％，长度分别为缺损宽度的2，3，4，5倍。没有皮质缺损的正常骨作为对照。对标本进行三点弯曲测试，力学指标包括最大负荷、最大功耗和断裂负荷。结果：当矩形缺损的宽度为横径的20％，缺损的长度达到宽度的4倍和5倍时，骨干的抗弯曲负荷较对照组降低，P值分别为0．007和0．014；当矩形的宽度为横径的10％，长度达到宽度的5倍时，骨干的抗弯曲负荷与对照组比较，差异显著（P=0．008）。两组标本达到破坏时的最大功耗均较正常对照降低（P〈0．05，P〈0．01）。结论：①骨干抗弯曲能力随缺损长度的增加降低。②从缺损的宽度和长度两个方面分析缺损对骨干的力学影响更为准确。

AIM： Cortical defect width and length can influence biomechanics of tubular bone. Many studies have been conducted to focus defect width, but there are little reports about defect length. This study explored the effect of cortical bone defect length on biomechanics of long tubular bone. METHODS： The experiment was performed at Department of Orthopaedics and Traumatology, Peking University People＇s Hospital from October to December 2007. ①Fifty-four fresh femur samples of adult goat, with no damage in appearance, coronal plane diameter of 14-17 mm and sagittal plane diameter of 14-17 mm, and bone length 〉 120 mm, were employed in this study. ② Unilateral square cortical defects were created by drills on tension site of long tubular bone; the defect width was 20% and 10% of the coronal diameter, and the length of defect was determined as 2, 3, 4, 5 folds of each width. Normal goat femurs served as controls. Three point bending test was performed for each sample to determine the biomechanical parameters such as maximum load, maximum power and breakage load. RESULTS： The maximum load and breakage load were significantly lower than control group when the defect width was 20% of diameter, and length was 5 fold and 4 fold of width （P=0.007 and 0.014）. When the defect width was 10% of diameter, and length was 5 fold of width, the maximum load and breakage load were statistically significant compared with control group （P=0.008）. The maximum power consumption of two sample groups was significantly decreased compared with control group （P 〈 0.05, P 〈 0.0 1）. CONCLUSION： ①Anti-bending ability of long tubular bone is decreased when cortical length is increased; ②Considering the influence of both cortical defect width and length would accurately explore the biomechanics of tubular bone with irregular defect.