Hammer Niels, Ondruschka Benjamin, Berghold Andrea, Kuenzer Thomas, Pregartner Gudrun, Scholze Mario, Schulze-Tanzil Gundula Gesine, Zwirner Johann
Division of Macroscopic and Clinical Anatomy, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria; Department of Orthopedic and Trauma Surgery, University of Leipzig, Leipzig, Germany; Division of Biomechatronics, Fraunhofer Institute for Machine Tools and Forming Technology Dresden, Germany.
Institute of Legal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Acta Biomater. 2023 Oct 1;169:168-178. doi: 10.1016/j.actbio.2023.07.036. Epub 2023 Jul 29.
Biomechanical experiments help link tissue morphology with load-deformation characteristics. A tissue-dependent minimum sample number is indispensable to obtain accurate material properties. Stress-strain properties were retrieved from human dura mater and scalp skin, exemplifying two distinct soft tissues. Minimum sample sizes necessary for a stable estimation of material properties were obtained in a simulation study. One-thousand random samples were sequentially drawn for calculating the point at which a majority of the estimators settled within a corridor of stability at given tolerance levels around a 'complete' reference for the mean, median and coefficient of variation. Stable estimations of means and medians can be achieved below sample sizes of 30 at a ± 20%-tolerance within 80%-conformity for scalp skin and dura. Lower tolerance levels or higher conformity dramatically increase the required sample size. Conformity was barely ever reached for the coefficient of variation. The parameter type appears decisive for achieving conformity. STATEMENT OF SIGNIFICANCE: Biomechanical trials utilizing human tissues are needed to obtain material properties for surgical repair, tissue engineering and modeling purposes. Linking tissue mechanics with morphology helps elucidate form-function relationships, the 'morpho-mechanical link'. For material properties to be accurate, it is vital to examine a minimum number of samples. This number may vary between tissues, and the effects of intrinsic tissue characteristics on data accuracy are unclear to date. This study used data obtained from human dura and skin to compute minimum sample sizes required for estimating material properties at a stable level. It was shown that stable estimations are possible at a ± 20%-tolerance within 80%-conformity below sample sizes of 30. Higher accuracy warrants much higher sample sizes for most material properties.
生物力学实验有助于将组织形态与负荷-变形特性联系起来。为了获得准确的材料特性，依赖于组织的最小样本数量是必不可少的。从人类硬脑膜和头皮皮肤中获取应力-应变特性，这是两种不同的软组织的例证。在一项模拟研究中获得了稳定估计材料特性所需的最小样本量。依次抽取1000个随机样本，以计算在围绕均值、中位数和变异系数的“完整”参考值的给定公差水平下，大多数估计值在稳定区间内稳定下来的点。对于头皮皮肤和硬脑膜，在样本量低于30且公差为±20%、符合度为80%的情况下，可以实现均值和中位数的稳定估计。更低的公差水平或更高的符合度会显著增加所需的样本量。变异系数几乎从未达到符合度。参数类型似乎对实现符合度起决定性作用。意义声明：需要利用人体组织进行生物力学试验，以获取用于手术修复、组织工程和建模目的的材料特性。将组织力学与形态学联系起来有助于阐明形态-功能关系，即“形态-力学联系”。为了使材料特性准确，检查最小数量的样本至关重要。这个数量可能因组织而异，并且迄今为止，内在组织特征对数据准确性的影响尚不清楚。本研究使用从人类硬脑膜和皮肤获得的数据来计算在稳定水平估计材料特性所需的最小样本量。结果表明，在样本量低于30且公差为±20%、符合度为80%的情况下，可以实现稳定估计。对于大多数材料特性，更高的精度需要更高的样本量。
