For radial head osteosynthesis, biodegradable implants are gaining in importance to minimize cartilage destruction and implant impingement and to supersede implant removal. Since loss of reduction and pseudarthrosis remain challenging complications, new implants should at least provide comparable biomechanical properties as commonly used metal implants. The objective of this study was to compare the treatment by polylactide pins to titanium screws and to quantify the produced cartilage defects. Eight pairs of human cadaver radii with a standardized Mason type II fracture were stabilized either by two 2.0-mm polylactide pins or titanium screws. The produced cartilage defects were quantified using an image analyzing software. Quasi-static loading was performed axially and transversally for 10 cycles each between 10 and 50 N. Afterward, implant loosening was tested by axial loading up to 10,000 cycles, followed by load to failure testing. Polylactide pins showed less construct stiffness under axial (p = 0.017) and transversal (p = 0.012) loading, and one polylactide pins construct failed after two cycles of transversal loading. At axial loading, a high correlation between bone mineral density and construct stiffness was observed among polylactide pins (R = 0.667; p = 0.071), which was not seen among titanium screws (R = 0.262; p = 0.531). No difference in implant loosening was recorded after 10,000 cycles (p = 0.237); however, one polylactide pins construct failed after 30 cycles and failure loads were higher for titanium screws (p=0.017). Polylactide pin produced smaller cartilage defects (p=0.012). In conclusion, simple radial head fractures treated by polylactide pins show less biomechanical stability than treated by titanium screws, particularly in osteoporotic bone which might lead to secondary loss of reduction. Due to smaller cartilage defects and equal properties under continuous loading, polylactide pins might represent a gentle alternative in patients with good bone quality making subsequent implant removal redundant.

中文翻译：

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可生物降解的销钉和钛螺钉对移位的displaced骨头骨折进行手术稳定的生物力学动态比较。

对于radial骨头的骨合成，可生物降解的植入物越来越重要，以最大程度地减少软骨破坏和植入物的撞击并取代植入物的去除。由于减少损失和假关节仍然是具有挑战性的并发症，因此新的植入物至少应提供与常用金属植入物相当的生物力学性能。这项研究的目的是比较聚乳酸针对钛螺钉的治疗，并量化产生的软骨缺损。八对具有标准梅森II型骨折的人尸体半径通过两个2.0毫米聚乳酸针或钛螺钉固定。使用图像分析软件对产生的软骨缺陷进行定量。沿轴向和横向执行准静态加载，每次加载10到50 N之间的10个循环。通过轴向载荷最多10,000个循环测试植入物的松动，然后进行载荷至破坏测试。聚乳酸针在轴向（p = 0.017）和横向（p = 0.012）载荷下显示出较小的结构刚度，并且一个聚丙交酯针在两次横向载荷循环后均失效。在轴向载荷下，在聚乳酸针之间观察到骨矿物质密度与构造刚度之间的高度相关性（R = 0.667； p = 0.071），而在钛螺钉中则没有发现（R = 0.262； p = 0.531）。10,000次循环后，没有发现种植体松动的差异（p = 0.237）；但是，一个聚丙交酯销钉构造在30个循环后会失效，并且钛螺钉的失效载荷更高（p = 0.017）。聚乳酸针产生较小的软骨缺损（p = 0.012）。结论，聚乳酸针治疗的简单radial骨头骨折比钛螺钉治疗的生物力学稳定性差，特别是在骨质疏松性骨中，这可能导致继发的复位损失。由于软骨缺损较小，并且在连续负荷下具有相同的特性，因此聚乳酸针在骨质量良好的患者中可以作为一种温和的选择，从而使随后的植入物去除变得多余。