Bartkowiak Tomasz, Madalińska Daria, Mietliński Patryk, Kaczmarek Jakub, Gapiński Bartosz, Pelic Marcin, Paczos Piotr
Institute of Mechanical Technology, Poznan University of Technology, 60-965 Poznań, Poland.
VETACARE-Dr. Philipp Winkels, 50374 Erftstadt, Germany.
Materials (Basel). 2023 Aug 30;16(17):5926. doi: 10.3390/ma16175926.
This study demonstrates a new method for quantifying thread engagement in mechanical connections and verifies its applicability using biomedical implants under push-out tests. The focus is on orthopedic plate implants employed for bone fracture fixation, which, by design, allow off-axis screw insertion to accommodate different contact conditions. Thread engagement is crucial in determining connection strength and stability. In medical practice, off-axis screw placement is usually necessary due to bone geometries and implant plate rigidity. To address this, the study proposes a quantification method using non-destructive testing with X-ray micro-computed tomography and automated image processing, although tuning the image processing parameters is vital for accurate and reliable results. This enables detailed 3D models of screw-plate interfaces for precise thread engagement measurement. The results show that thread engagement decreases with both, increased off-axis insertion angles and higher torque during insertion. Correlation analysis reveals a strong relationship (R > 0.6) between average thread engagement and push-out strength, underscoring the importance of proper screw placement for stable fixation.
本研究展示了一种量化机械连接中螺纹啮合的新方法，并通过推出试验验证了其在生物医学植入物中的适用性。重点是用于骨折固定的骨科接骨板植入物，其设计允许偏轴螺钉插入以适应不同的接触条件。螺纹啮合对于确定连接强度和稳定性至关重要。在医学实践中，由于骨骼几何形状和植入接骨板的刚性，通常需要进行偏轴螺钉放置。为了解决这个问题，该研究提出了一种使用X射线微计算机断层扫描和自动图像处理进行无损检测的量化方法，尽管调整图像处理参数对于获得准确可靠的结果至关重要。这能够生成螺钉-接骨板界面的详细三维模型，以便精确测量螺纹啮合。结果表明，螺纹啮合随着偏轴插入角度的增加和插入过程中扭矩的增大而减小。相关性分析揭示了平均螺纹啮合与推出强度之间存在很强的关系（R>0.6），强调了正确放置螺钉以实现稳定固定的重要性。
