Navacchia Alessandro, Clary Chadd W, Wilson Hayden L, Behnam Yashar A, Rullkoetter Paul J
Center for Orthopaedic Biomechanics, The University of Denver, CO, USA.
Center for Orthopaedic Biomechanics, The University of Denver, CO, USA.
J Biomech. 2018 Aug 22;77:115-123. doi: 10.1016/j.jbiomech.2018.06.024. Epub 2018 Jul 6.
As fixation of cementless total knee replacement components during the first 4-6 weeks after surgery is crucial to establish bony ingrowth into the porous surface, several studies have quantified implant-bone micromotion. Relative motion between the tray and bone can be measured in vitro, but the full micromotion contour map cannot typically be accessed experimentally. Finite element models have been employed to estimate the full micromotion map, but have not been directly validated over a range of loading conditions. The goal of this study was to develop and validate computational models for the prediction of tray-bone micromotion under simulated activities of daily living. Gait, stair descent and deep knee bend were experimentally evaluated on four samples of a cementless tibial tray implanted into proximal tibial Sawbones™ constructs. Measurements of the relative motion between the tray and the anterior cortical shell were collected with digital image correlation and used to validate a finite element model that replicated the experiment. Additionally, a probabilistic analysis was performed to account for experimental uncertainty and determine model sensitivity to alignment and frictional parameters. The finite element models were able to distinguish between activities and capture the experimental trends. Best-matching simulations from the probabilistic analysis matched measured displacement with an average root mean square (RMS) difference of 14.3 µm and Pearson-product correlation of 0.93, while the mean model presented an average RMS difference of 27.1 µm and a correlation of 0.8. Maximum deviations from average experimental measurements were 40.5 and 87.1 µm for the best-matching and average simulations, respectively. The computational pipeline developed in this study can facilitate and enhance pre-clinical assessment of novel implant components.
由于无骨水泥全膝关节置换组件在术后最初4 - 6周的固定对于实现骨长入多孔表面至关重要，因此多项研究对植入物与骨之间的微动进行了量化。托盘与骨之间的相对运动可在体外测量，但通常无法通过实验获取完整的微动轮廓图。有限元模型已被用于估计完整的微动图，但尚未在一系列加载条件下得到直接验证。本研究的目的是开发并验证用于预测在模拟日常生活活动下托盘与骨之间微动的计算模型。对植入近端胫骨Sawbones™结构的四个无骨水泥胫骨托盘样本进行了步态、下楼梯和深度屈膝的实验评估。通过数字图像相关技术收集托盘与前皮质壳之间相对运动的测量数据，并用于验证复制该实验的有限元模型。此外，进行了概率分析以考虑实验不确定性，并确定模型对对准和摩擦参数的敏感性。有限元模型能够区分不同活动并捕捉实验趋势。概率分析中最佳匹配模拟与测量位移的平均均方根（RMS）差异为14.3 µm，皮尔逊积相关系数为0.93，而平均模型的平均RMS差异为27.1 µm，相关系数为0.8。最佳匹配模拟和平均模拟与平均实验测量值的最大偏差分别为40.5和87.1 µm。本研究中开发的计算流程可促进和加强对新型植入组件的临床前评估。
