Mechanisms of Failure Following Simulated Repetitive Lifting A Clinically Relevant Biomechanical Cadaveric Study
Mechanisms of Failure Following Simulated Repetitive Lifting A Clinically Relevant Biomechanical Cadaveric Study
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DOI：
10.1097/brs.0000000000003270
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发表时间：
2020-03-15
期刊：
影响因子：
3
通讯作者：
Costi, John J.
中科院分区：
文献类型：
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作者：
Amin, Dhara B.;Tavakoli, Javad;Costi, John J.
研究设计.在模拟重复性举重过程中椎间盘内部应变与组织损伤相关的生物力学分析。Objective.了解模拟安全和不安全重复提升过程中的故障模式。背景数据摘要。重复性举升已被证明会导致腰椎间盘突出症（LDH），体外研究已经对重复性负荷对LDH的影响有了定性的了解。然而，没有研究测量内部椎间盘应变，并随后与椎间盘损伤。方法.对30具人尸体腰椎功能性脊柱单元在安全和不安全压缩水平下进行了相当于1年的模拟重复提升，并结合屈曲（13-15度）和右轴向旋转（2度）进行了20，000次循环或直至失效。安全或不安全的提升被施加为压缩载荷，以分别模拟保持20 kg的重量接近身体或与身体保持一臂长。测量最大剪切应变（MSS），并根据轴向测试后磁共振成像（MRI）和肉眼图像确定9个区域的椎间盘损伤评分。结果在安全提升组中，20%的样本在20,000次循环之前由于终板失效而失效，而在不安全组中，这一比例为67%。安全提升组中超过一半的标本通过椎间盘突出或LDH失败，而不安全组中只有20%通过突出失败。各部位MRI与大体损伤评分均呈显著正相关（r（s）> 0.385，P < 0.049）。在左侧区域，MSS与宏观损伤评分（r（s）= 0.486，P < 0.037）和MSS与失效模式（r（s）= 0.724，P = 0.018，仅椎间盘失效标本）之间存在显著正相关。Pfirrmann 3级椎间盘与随后的LDH密切相关（P = 0.003）。结论随着椎间盘损伤从突出进展为LDH，在施加旋转的对侧观察到剪切应变增加。施加较大的压缩载荷以模拟不安全的提升导致终板频繁的早期失效，然而，在安全提升下施加相似屈曲角度的较小压缩载荷导致失效前更多的载荷循环，其中失效部位更可能是椎间盘。我们的研究表明，与安全移位相比，不安全移位导致更大的损伤风险，LDH和椎间盘突出在后/后外侧区域更常见。
Study Design. A biomechanical analysis correlating internal disc strains and tissue damage during simulated repetitive lifting. Objective. To understand the failure modes during simulated safe and unsafe repetitive lifting. Summary of Background Data. Repetitive lifting has been shown to lead to lumbar disc herniation (LDH).In vitrostudies have developed a qualitative understanding of the effect of repetitive loading on LDH. However, no studies have measured internal disc strains and subsequently correlated these with disc damage. Methods. Thirty human cadaver lumbar functional spinal units were subjected to an equivalent of 1 year of simulated repetitive lifting under safe and unsafe levels of compression, in combination with flexion (13-15 degrees), and right axial rotation (2 degrees) for 20,000 cycles or until failure. Safe or unsafe lifting were applied as a compressive load to mimic holding a 20 kg weight either close to, or at arm's length, from the body, respectively. Maximum shear strains (MSS) were measured, and disc damage scores were determined in nine regions from axial post-test magnetic resonance imaging (MRI) and macroscopic images. Results. Twenty percent of specimens in the safe lifting group failed before 20,000 cycles due to endplate failure, compared with 67% in the unsafe group. Over half of the specimens in the safe lifting group failed via either disc protrusion or LDH, compared with only 20% via protrusion in the unsafe group. Significant positive correlations were found between MRI and macroscopic damage scores in all regions (r(s) > 0.385,P < 0.049). A significant positive correlation was observed in the left lateral region for MSSversusmacroscopic damage score (r(s) = 0.486,P < 0.037) and MSSversusfailure mode (r(s) = 0.724,P = 0.018, only specimens with disc failure). Pfirrmann Grade 3 discs were strongly associated with subsequent LDH (P = 0.003). Conclusion. Increased shear strains were observed in the contralateral side to the applied rotation as disc injury progressed from protrusion to LDH. Larger compressive loads applied to simulate unsafe lifting led to frequent early failure of the endplate, however, smaller compressive loads at similar flexion angles applied under safe lifting led to more loading cycles before failure, where the site of failure was more likely to be the disc. Our study demonstrated that unsafe lifting leads to greater risk of injury compared with safe lifting, and LDH and disc protrusion were more common in the posterior/posterolateral regions.