Shields Kelly J, Owen John R, Wayne Jennifer S
Department of Biomedical Engineering, Orthopaedic Research Laboratory, Virginia Commonwealth University, Richmond, VA 23284-3067, USA.
J Biomech Eng. 2009 Jun;131(6):061005. doi: 10.1115/1.3116156.
Characterizing the biomechanical and biotribological properties for articular surfaces in healthy, damaged, and repaired states will both elucidate the understanding of mechanical degradation and lubricating phenomena and enhance the development of functional tissue engineered cartilage and surgical repair techniques. In recent work, a new methodology involving concomitant linear translational and oscillating rotational motion was developed to determine the frictional and wear characteristics of articular cartilage. The impetus of this work was to further characterize the biomechanical characteristics from stress relaxation and dynamic cyclical indentation testing of normal and damaged articular cartilage and to correlate the biotribological characteristic findings with the biomechanical data. Quasilinear viscoelastic (QLV) theory was used to curve fit the stress-relaxation data, while the dynamic data were used both to determine the dynamic properties through fast Fourier transform analysis and to validate the dynamic behavior based on the properties obtained from the QLV theory. Comparisons of the curve-fit parameters showed a significant decrease in pre- versus postwear elastic response, A (p<0.04), and viscous response, c (p<0.01). In addition, the short term relaxation time, tau1 (p<0.0062), showed a significant decrease between surfaces with and without a defect. The magnitude of the complex modulus from dynamic tests revealed a decrease due to wear, lGlpostwearlGlprewear<1 (p<0.05). The loss factor, tan delta, was generally greater while lGl was less for those specimens experiencing rotation. A linear regression analysis was performed to correlate microstatic and microinitial with the curve-fit QLV parameters, A, B, c, tau1, and tau2. Increasing coefficients of friction correlated with decreases in the elastic response, A, viscous response, c, and the short term relaxation time constant, tau1, while B became increasingly nonlinear and tau2 became shorter postwear. Qualitatively, scanning electron microscopy photographs revealed the mechanical degradation of the tissue surface due to wear. Surfaces with a defect had an increased amount of wear debris, which ultimately contributed to third body wear. Surfaces without a defect had preferentially aligned abrasions, while those surfaces not within the wear path showed no signs of wear. The efficacy of various repair techniques and innovative repair tissue models in comparison to normal and worn articular surface tissue can be determined through experimental designs involving both biomechanical and biotribological parameter characterizations. The development of this comprehensive testing scenario involving both biotribological and biomechanical characteristics is essential to the continued development of potential articular repair tissue.
表征健康、受损和修复状态下关节表面的生物力学和生物摩擦学特性，将有助于阐明对机械降解和润滑现象的理解，并促进功能性组织工程软骨和手术修复技术的发展。在最近的工作中，开发了一种新方法，该方法涉及伴随的线性平移和振荡旋转运动，以确定关节软骨的摩擦和磨损特性。这项工作的目的是通过对正常和受损关节软骨的应力松弛和动态循环压痕测试进一步表征生物力学特性，并将生物摩擦学特性研究结果与生物力学数据相关联。准线性粘弹性（QLV）理论用于对应力松弛数据进行曲线拟合，而动态数据则用于通过快速傅里叶变换分析确定动态特性，并基于从QLV理论获得的特性验证动态行为。曲线拟合参数的比较表明，磨损前后的弹性响应A（p<0.04）和粘性响应c（p<0.01）显著降低。此外，短期松弛时间tau1（p<0.0062）在有缺陷和无缺陷表面之间显著降低。动态测试中复模量的大小显示由于磨损而降低，|G|postwear<|G|prewear（p<0.05）。对于那些经历旋转的试样，损耗因子tan delta通常更大，而|G|更小。进行线性回归分析，以将微静态和微初始值与曲线拟合的QLV参数A、B、c、tau1和tau2相关联。摩擦系数增加与弹性响应A、粘性响应c和短期松弛时间常数tau1的降低相关，而B变得越来越非线性，tau2在磨损后变短。定性地说，扫描电子显微镜照片显示了由于磨损导致的组织表面机械降解。有缺陷的表面有更多的磨损碎屑，这最终导致了三体磨损。无缺陷的表面有优先排列的擦伤，而不在磨损路径内的表面没有磨损迹象。通过涉及生物力学和生物摩擦学参数表征的实验设计，可以确定各种修复技术和创新修复组织模型与正常和磨损关节表面组织相比的功效。这种涉及生物摩擦学和生物力学特性的综合测试方案的开发对于潜在关节修复组织的持续发展至关重要。
