BACKGROUND Lateral tibial split fractures (LTSF) usually require surgical therapy with screw or plate osteosynthesis. Excellent anatomical reduction of the fracture is thereby essential to avoid post-traumatic osteoarthritis. In clinical practice, a gap and step of 2 mm have been propagated as maximum tolerable limit. To date, biomechanical studies regarding tibial fractures have been limited to pressure measurement, but the relationship between dissipated energy (DE) as a friction parameter and reduction accuracy in LTSF has not been investigated. In past experiments, we developed a new method to measure DE in ovine knee joints. To determine weather non-anatomical fracture reduction with lateral gap or vertical step condition leads to relevant changes in DE in the human knee joint, we tested the applicability of the new method on human LTSFs and investigated whether the current limit of 2 mm gap and step is durable from a biomechanical point of view. METHODS Seven right human, native knee joint specimens were cyclically moved under 400 N axial load using a robotic system. During the cyclic motion, the flexion angle and the respective torque were recorded and the DE was calculated. First, DE was measured after an anterolateral approach had been performed (condition "native"). Then a LTSF was set with a chisel, reduced anatomically, fixed with two set screws and DE was measured ("even"). DE of further reductions was then measured with gaps of 1 mm and 2 mm, and a 2 mm step down or a 2 mm step up was measured. RESULTS We successfully established a measurement protocol for DE in human knee joints with LTSF. While gaps led to small though statistically significant increase (1 mm gap:ΔDE compared with native = 0.030 J/cycle, (+ 21%), p = 0.02; 2 mm gap:ΔDE = 0.032 J/cycle, (+ 22%), p = 0.009), this increase almost doubled when reducing in a step-down condition (ΔDE = 0.058 J/cycle, (+ 56%), p = 0.042) and even tripled in the step-up condition (ΔDE = 0.097 J/cycle, (+ 94%), p = 0.004). CONCLUSIONS Based on our biomechanical findings, we suggest avoiding step conditions in the daily work in the operating theatre. Gap conditions can be handled a bit more generously.

中文翻译：

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胫骨平台外侧骨折复位精度对关节内摩擦的影响-生物力学研究。

背景技术胫骨外侧裂骨折（LTSF）通常需要通过螺钉或板式骨固定术进行手术治疗。因此，出色的骨折解剖复位对于避免创伤后骨关节炎至关重要。在临床实践中，已将2mm的间隙和步长扩展为最大容许极限。迄今为止，有关胫骨骨折的生物力学研究仅限于压力测量，但尚未研究耗散能量（DE）作为摩擦参数与LTSF复位精度之间的关系。在过去的实验中，我们开发了一种新的方法来测量羊膝关节的DE。要确定由于横向间隙或垂直阶跃条件导致的天气非解剖学骨折的减少是否导致人膝关节的DE发生相关变化，我们测试了该新方法在人类LTSF上的适用性，并从生物力学的角度研究了2 mm间隙和台阶的电流极限是否持久。方法使用机器人系统在400 N轴向载荷下周期性地移动七个右人体原生膝关节标本。在循环运动期间，记录了弯曲角度和相应的扭矩并计算了DE。首先，在进行前外侧入路（条件为“自然”）后测量DE。然后，用凿子将LTSF固定，在解剖上缩小，用两个固定螺钉固定，并测量DE（“偶数”）。然后以1mm和2mm的间隙测量进一步减小的DE，并测量2mm的减小量或2mm的增大量。结果我们成功地建立了使用LTSF的人膝关节中DE的测量方案。虽然间隙导致了很小但统计上显着的增加（1 mm间隙：ΔDE与原始值相比= 0.030 J /周期，（+ 21％），p = 0.02; 2 mm间隙：ΔDE= 0.032 J /周期，（+ 22％） ，p = 0.009），在降压条件下降低（ΔDE= 0.058 J / cycle，（+ 56％），p = 0.042）时几乎增加了一倍，在升压条件下（ΔDE= 0.097 J）甚至增加了两倍/周期，（+ 94％），p ＝ 0.004）。结论基于我们的生物力学发现，我们建议避免在手术室的日常工作中使用阶梯状条件。差距条件可以更宽泛地处理。042）甚至在升压条件下增加了三倍（ΔDE= 0.097 J / cycle，（+ 94％），p = 0.004）。结论基于我们的生物力学发现，我们建议避免在手术室的日常工作中使用阶梯状条件。差距条件可以更宽泛地处理。042）甚至在升压条件下增加了三倍（ΔDE= 0.097 J / cycle，（+ 94％），p = 0.004）。结论基于我们的生物力学发现，我们建议避免在手术室的日常工作中使用阶梯状条件。差距条件可以更宽泛地处理。