OBJECTIVE  The aim of this study was to compare the locking compression plate (LCP) with polyaxial locking system (PLS) using single cycle to failure 4-point bending test and to investigate the behaviour of PLS with screws inserted mono- and polyaxially using cyclic fatigue test in two bending directions. MATERIALS AND METHODS  Tests were performed on bone surrogates in a fracture gap model. The 3.5 LCP and 3.5 PLS plates were tested in single cycle to failure. The 3.5 PLS plates with mono- and polyaxial screws were compared in a cyclic fatigue tests in two orthogonal directions. For both experiments, micro-computed tomography (CT) scans were performed pre- and post-testing to investigate the connections between the screw head and the plate hole. Means of forces and cycles needed to failure were statistically compared. RESULTS  The PLS plates were on average 30% weaker than LCP plates. Mode of failure was plate bending in the single cycle to failure tests, and plate breakage in the cyclic fatigue tests. Neither screw breakage nor loss of the screw-plate interface occurred. Mono- and polyaxial constructs performed similarly when loaded in the same direction. Micro-CT revealed no additional internal cracks in the plates or screws after testing. It also showed for both PLS and LCP that there was only partial contact of the screw head with the plate hole. CLINICAL RELEVANCE  PLS offers a durable locking system, even when the screws are placed polyaxially. The weaker bending properties of the PLS compared with LCP should be considered during preoperative planning.

中文翻译：

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断裂间隙模型中多轴锁定板的机械性能和螺杆角度的影响。

目的本研究的目的是比较单周期的锁紧压缩板（LCP）与多轴锁紧系统（PLS）到失效的4点弯曲试验，并通过循环疲劳研究单轴和多轴插入螺钉的PLS的性能在两个弯曲方向上进行测试。材料与方法在骨折缝隙模型中对骨替代物进行了测试。3.5 LCP和3.5 PLS板在单个循环中进行了测试，直至失效。在两个正交方向上的循环疲劳测试中比较了带有单轴和多轴螺钉的3.5 PLS板。对于这两个实验，在测试前和测试后均进行了微计算机断层扫描（CT）扫描，以研究螺钉头与板孔之间的连接。统计比较失效所需的力和周期的平均值。结果PLS板平均比LCP板弱30％。失效模式是单轮弯曲至失效测试，而钢板在循环疲劳测试中断裂。既没有发生螺钉断裂也没有发生螺钉-板界面的损失。当沿相同方向加载时，单轴和多轴构造的性能相似。测试后，Micro-CT显示板或螺钉中没有其他内部裂纹。对于PLS和LCP，这也表明，螺钉头与板孔仅部分接触。临床相关性即使将螺钉多轴放置，PLS仍可提供耐用的锁定系统。在术前计划中，应考虑PLS与LCP相比较弱的弯曲特性。失效模式是单轮弯曲至失效测试，而钢板在循环疲劳测试中断裂。既没有发生螺钉断裂也没有发生螺钉-板界面的损失。当沿相同方向加载时，单轴和多轴构造的性能相似。测试后，Micro-CT显示板或螺钉中没有其他内部裂纹。对于PLS和LCP，这也表明，螺钉头与板孔仅部分接触。临床相关性即使将螺钉多轴放置，PLS仍可提供耐用的锁定系统。在术前计划中，应考虑PLS与LCP相比弯曲性能较弱。失效模式是单轮弯曲至失效测试，而钢板在循环疲劳测试中断裂。既没有发生螺钉断裂也没有发生螺钉-板界面的损失。当沿相同方向加载时，单轴和多轴构造的性能相似。测试后，Micro-CT显示板或螺钉中没有其他内部裂纹。对于PLS和LCP，这也表明，螺钉头与板孔仅部分接触。临床相关性即使将螺钉多轴放置，PLS仍可提供耐用的锁定系统。在术前计划中，应考虑PLS与LCP相比较弱的弯曲特性。当沿相同方向加载时，单轴和多轴构造的性能相似。测试后，Micro-CT显示板或螺钉中没有其他内部裂纹。对于PLS和LCP，这也表明，螺钉头与板孔仅部分接触。临床相关性即使将螺钉多轴放置，PLS仍可提供耐用的锁定系统。在术前计划中，应考虑PLS与LCP相比较弱的弯曲特性。当沿相同方向加载时，单轴和多轴构造的性能相似。测试后，Micro-CT显示板或螺钉中没有其他内部裂纹。对于PLS和LCP，这也表明，螺钉头与板孔仅部分接触。临床相关性即使将螺钉多轴放置，PLS仍可提供耐用的锁定系统。在术前计划中，应考虑PLS与LCP相比较弱的弯曲特性。