球窝型人工颈椎间盘关键结构设计对摩擦学性能影响规律研究

Artificial disc is the key surgical prosthesis to cure severe cervical spondylosis. However, it suffers friction and wear failure under complex mechanical and physical human body environment, which greatly reduce its long-term reliability. Nowadays, the Chinese market of artificial cervical disc is totally occupied by European and American products. With the intensification of population aging and the increasing youthful morbidity, it is imperative to develop national prosthesis with high wear resistance and long life in service. In this process, the biotribological behavior becomes the key problem. However, the existing achievements mostly focus on the selection and optimization of articulation materials under ball / pin-on-disc pair to improve the wear resistance. A few studies involving prosthesis are also limited to specific structural design. There are still no reports aimed at the effect of structural design of cervical prosthesis on biotribological properties. Hence, in this project, the bionic structural design of ball-on-socket artificial cervical disc will be studied based on the database of Chinese cervical physiological parameters. The influence of key design factors (clearance and radius, component height, translation range, etc.) on the stress and strain distribution, lubrication state and mechanism, wear performance and mechanism of cervical spine and prosthesis will also be revealed. Thus, this project could improve the basic theory aimed at the relationship between structural design and biotribological properties. In addition, it could optimize the key structural design parameters of national prosthesis and provide technical supports for the design and manufacture of high-performing artificial disc.

人工椎间盘是手术治疗严重颈椎病的关键假体，但在人体复杂力学和生理环境作用下，假体关节面易出现摩擦磨损失效，极大降低了其长期可靠性。目前人工颈椎间盘国内市场全部被欧美产品占领，随着人口老龄化加剧和发病率日益年轻化，开发高耐磨长寿命国产化的假体已势在必行，而生物摩擦学问题更是其中的关键。但国内外现有成果大多集中在关节面耐磨材料选择和优化方面，且结构配副多以球/销盘为主，少量采用假体作为对象的研究也都限定在特定结构设计，目前很少有文献报道假体结构设计对摩擦学性能的影响规律。本项目将基于国人颈椎生理参数数据库，研究球窝型人工颈椎间盘仿生结构设计，揭示关键设计因素（间隙与半径、各部件高度、假体平移幅度等）对颈椎和假体应力应变分布特征、润滑状态与机制、磨损性能与机理的影响规律，建立并完善结构设计与摩擦学性能作用关系的基础理论，优化国产假体关键结构设计参数，为研发高耐磨人工假体奠定理论和技术基础。

人工椎间盘是手术治疗严重颈椎病的关键假体，但在人体复杂力学和生理环境作用下，假体关节面易出现摩擦磨损失效，极大降低了其长期可靠性。目前国内外成果大多集中在关节面耐磨材料选择和优化方面，且结构配副多以球/销盘为主，少量采用假体作为对象的研究也都限定在特定结构设计，很少有文献报道假体结构设计对摩擦学性能的影响规律。本项目基于国人颈椎生理参数数据库，研究了球窝型人工颈椎间盘仿生结构设计，揭示了关键设计因素（间隙与半径、各部件高度、假体平移幅度等）对假体应力应变分布特征、润滑状态与机制、磨损性能与机理的影响规律，优化了国产假体关键结构设计参数。结果表明：两款球窝假体应力集中均发生在相对运动关节面和组件连接处，且髓核上表面应力最大值呈现环形分布特征。滑动型相对固定型，优势是运动模式更丰富、应力传递更均匀，劣势是复杂运动会加大髓核应力（从1.36MPa到2.43MPa）。固定型的髓核变形量仅是滑动型的22.5%，但总变形均集中在前后两端。关节面参数对应力影响权重是球缺高度＞球头半径＞球窝间隙，且高度和半径越大、间隙越小越好；对润滑状态影响权重是球窝间隙＞球头半径，且间隙越小、半径越大润滑状态越佳。半径、间隙和高度3参数最佳组合为16.00mm、10.0μm和1.2mm，在此组合下滑动型假体最大应力数值最小（2.79MPa），且润滑状态最佳（λ值0.573）。经过8MC体外磨损测试，最优设计下的TC4-XPE和CoCrMo-XPE配副产品金属上终板部件表面损伤模式均以划痕为主，磨损机理为磨粒磨损。TC4-XPE中聚乙烯髓核损伤特征以划痕、塑性疲劳变形为主，磨损机理为磨粒磨损和粘着磨损，但CoCrMo-XPE的聚乙烯髓核损伤特征以划痕、犁沟为主，磨损机理为磨粒磨损。两种配副的磨屑形貌特征相似，均以块状磨屑为主，伴随有絮状、带状、板条状、断裂状，但TC4-XPE还产生大量团聚状磨屑。两种配副的磨屑粒径特征差异较大，TC4-XPE的粒径最集中位置是14.47μm，而CoCrMo-XPE则是31.50μm。上述结果为研发高耐磨人工假体奠定了理论和技术基础。