Roland Michael, Diebels Stefan, Wickert Kerstin, Pohlemann Tim, Ganse Bergita
Chair of Applied Mechanics, Saarland University, Saarbrücken, Germany.
Department of Trauma, Hand and Reconstructive Surgery, Departments and Institutes of Surgery, Saarland University, Homburg, Germany.
Front Bioeng Biotechnol. 2024 Jul 23;12:1420047. doi: 10.3389/fbioe.2024.1420047. eCollection 2024.
Bone healing can be improved by axial micromovement, as has been shown in animals and human patients with external fixators. In the development of smart fracture plates, the ideal amount of stroke for different fracture types in the different healing stages is currently unknown. It was hypothesized that the resulting strain in the fracture gap of a simple tibial shaft fracture does not vary with the amount of axial stroke in the plate, the fracture gap size, and the fracture angle. With finite element simulations based on body donation computed tomography data, the second invariant of the deviatoric strain tensor (J2), strain energy density, hydrostatic strain, octahedral shear strain, and percentage of the fracture gap in the "perfect healing window" were computed for different gap sizes (1-3 mm), angles (5°-60°), and plate stroke levels (0.05-0.60 mm) in three healing stages. Multiple linear regression analyses were performed. Findings showed that an active fracture plate should deliver an axial stroke in the range of 0.10-0.45 mm. Different optimal stroke values were found for each healing phase, namely, 0.10-0.25 mm for the first, 0.10 mm for the second, and 0.35-0.45 mm for the third healing phase, depending on the fracture gap size and less on the fracture angle. J2, hydrostatic strain, octahedral shear strain and the strain energy density correlated with the fracture gap size and angle (all < 0.001). The influence of the fracture gap size and angle on the variability (adjusted R) in several outcome measures in the fracture gap was shown to vary throughout healing. The contribution to the variability of the percentage of the fracture gap in the perfect healing window was greatest during the second healing phase. For J2, strain energy density, hydrostatic strain, and octahedral shear strain, the fracture gap size showed the greatest contribution in the third fracture healing phase, while the influence of fracture angle was independent of the healing phase. The present findings are relevant for implant development and to design clinical studies that aim to accelerate fracture healing using axial micromovement.
正如在动物和使用外固定器的人类患者中所显示的那样，轴向微动可以促进骨愈合。在智能骨折板的研发过程中，目前尚不清楚不同愈合阶段中不同骨折类型的理想行程量。研究假设，单纯胫骨干骨折骨折间隙中的应变不会随钢板的轴向行程量、骨折间隙大小和骨折角度而变化。基于尸体捐赠计算机断层扫描数据进行有限元模拟，计算了三个愈合阶段中不同间隙大小（1-3毫米）、角度（5°-60°）和钢板行程水平（0.05-0.60毫米）下的偏应变张量第二不变量（J2）、应变能密度、静水应变、八面体剪应变以及处于“完美愈合窗口”的骨折间隙百分比。进行了多元线性回归分析。研究结果表明，主动式骨折板的轴向行程应在0.10-0.45毫米范围内。每个愈合阶段都发现了不同的最佳行程值，即第一愈合阶段为0.10-0.25毫米，第二愈合阶段为0.10毫米，第三愈合阶段为0.35-0.45毫米，这取决于骨折间隙大小，而对骨折角度的依赖性较小。J2、静水应变、八面体剪应变和应变能密度与骨折间隙大小和角度相关（均P<0.001）。骨折间隙大小和角度对骨折间隙中几种结果测量指标变异性（调整R）的影响在整个愈合过程中有所不同。在第二愈合阶段，处于完美愈合窗口的骨折间隙百分比对变异性的贡献最大。对于J2、应变能密度、静水应变和八面体剪应变，骨折间隙大小在第三骨折愈合阶段的贡献最大，而骨折角度的影响与愈合阶段无关。本研究结果与植入物研发以及设计旨在利用轴向微动加速骨折愈合的临床研究相关。
