锁骨显微压痕硬度的分布特征及临床意义

Distribution characteristics and clinical significance of clavicle microindentation hardness

目的探讨锁骨不同节段和不同层面骨显微压痕硬度的分布特征及临床意义。方法选取3具中国人新鲜尸体标本中的右侧锁骨,参考Allman分型将锁骨分为近段、中段、远段三节段。使用慢速锯垂直于各节段长轴等距精确切割,制备成15层厚约3 mm的骨骼试样(近段3层,中段7层,远段5层),并将每层试样划分为前、后、上、下四个方位。应用维氏显微硬度测量仪测量锁骨不同层面不同方位的显微压痕硬度值,测量单位为HV(kgf/mm2)。记录并分析锁骨硬度分布规律。结果锁骨皮质骨共测量180个部位,900个测量值;松质骨共测量45个部位,225个测量值。结果显示:(1)锁骨皮质骨整体硬度为(35.9±8.1)HV,其中近段为(33.8±6.1)HV,中段为(41.3±6.8)HV,远段为(29.7±5.4)HV,中段硬度大于两端(P<0.05);(2)松质骨整体硬度为(30.7±6.2)HV,其中近段为(29.2±2.9)HV,中段为(34.5±5.5)HV,远段为(26.3±5.1)HV,三节段硬度值差异有统计学意义(P<0.05);(3)皮质骨硬度最大层面为中段第5层,硬度值为(44.8±8.6)HV,硬度最小的层面是远段第4层,硬度值为(28.0±3.5)HV(P<0.05);(4)松质骨硬度最大层面为中段第5层,硬度值为(36.8±5.1)HV,硬度最小层面为远段第5层,硬度值为(23.0±4.4)HV(P<0.05);(5)锁骨三节段不同方位的骨硬度值组间比较差异无统计学意义(P>0.05)。结论锁骨不同节段、不同层面的骨显微压痕硬度差异较大,但皮质骨与松质骨变化规律一致,中段骨硬度明显高于近段和远段,呈现由中段向两端逐步减小的梯度分布规律。该数据能够指导设计符合生理状态下锁骨应力传导特性的3D打印内置物,并对模拟生理状态下锁骨建模及有限元分析提供良好的数据支持。

Objective To investigate the distribution characteristics and significance of bone hardness in different segments and layers of clavicle. Methods The right clavicles of three fresh Chinese corpses were taken and then divided into proximal, middle and distal segments according to Allman's classification. The clavicles were cut with diamond saw in the vertical of long axis equidistant exactly into 15 layers (proximal: 3 layers;midshaft: 7 layers;distal: 5 layers), and each layer was divided into four directions: superior, inferior, anterior, and posterior. The bone hardness were measured by Vickers microindentation, HV(kgf/mm2). The distribution of bone hardness was recorded and analyzed. Results A total of 180 parts of cortical bone were measured, generating 900 measurements. Meanwhile, a total of 45 parts of cancellous bone were measured, generating 225 measurements. We found that:(1)The average hardness of cortical bone was (35.9±8.1)HV, and the midshaft segment [(41.3±6.8)HV] was harder than the proximal segment [(33.8±6.1)HV] and the distal segment [(29.7±5.4)HV](P<0.05);(2)The average hardness of cancellous bone was (30.7±6.2)HV, and there were significant differences among the midshaft segment [(34.5±5.5)HV], the proximal segment [(29.2±2.9)HV] and the distal segment [(26.3±5.1)HV](P<0.05);(3)for cortical bone, the hardest segment was the fifth layer of the midshaft segment [(44.8±8.6)HV] while the most soft segment was the fourth layer of the distal segment [(28.0±3.5)HV](P<0.05);(4)for cancellous bone, the hardest segment was the fifth layer of the midshaft segmnet [(36.8±5.1)HV] while the most soft was the fifth layer of the distal segment [(23.0±4.4)HV](P<0.05);(5)There were no statistically significant differences among four directions of segments(P>0.05). Conclusion The microindentation hardness varies greatly among different segments and layers of the clavicles. The cortical bone and cancellous bone have consistent hardness changes, which shows that the middle segment is obviously harder than the proximal and distal segments with a gradually gradient decreasing trend from the middle to both ends. The data can be used to guide the design of 3D printing implants that conform to the stress conduction characteristics of the clavicle under physiological conditions, and provide good data support for the modeling and finite element analysis of the clavicle under simulated physiological conditions.