Most commercial spine analogues are not intended for biomechanical testing, and those developed for this purpose are expensive and yet still fail to replicate the mechanical performance of biological specimens. Patient-specific analogues that address these limitations and avoid the ethical restrictions surrounding the use of human cadavers are therefore required. We present a method for the production and characterisation of biofidelic, patient-specific, Spine Motion Segment (SMS = 2 vertebrae and the disk in between) analogues that allow for the biological variability encountered when dealing with real patients. Porcine spine segments (L1–L4) were scanned by computed tomography, and 3D models were printed in acrylonitrile butadiene styrene (ABS). Four biological specimens and four ABS motion segments were tested, three of which were further segmented into two Vertebral Bodies (VBs) with their intervertebral disc (IVD). All segments were loaded axially at 0.6 mm·min⁻¹ (strain-rate range 6×10⁻⁴ s⁻¹–10×10⁻⁴ s⁻¹). The artificial VBs behaved like biological segments within the elastic region, but the best two-part artificial IVD were ∼15% less stiff than the biological IVDs. High-speed images recorded during compressive loading allowed full-field strains to be produced. During compression of the spine motion segments, IVDs experienced higher strains than VBs as expected. Our method allows the rapid, inexpensive and reliable production of patient-specific 3D-printed analogues, which morphologically resemble the real ones, and whose mechanical behaviour is comparable to real biological spine motion segments and this is their biggest asset.

中文翻译：

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脊柱运动节段— I：特定对象的模拟模型的概念

大多数商业脊柱类似物不打算用于生物力学测试，而为此目的开发的类似物价格昂贵，但仍无法复制生物样本的机械性能。因此，需要针对患者的类似物，以解决这些局限性并避免围绕使用人类尸体的道德限制。我们提出了一种生产和表征生物理想的，针对患者的脊柱运动节段（SMS = 2椎骨，椎间盘位于其间）类似物的方法，该方法可以应对实际患者时遇到的生物学差异。通过计算机断层扫描扫描猪的脊柱节段（L1-L4），并在丙烯腈-丁二烯-苯乙烯（ABS）中打印3D模型。测试了四个生物样本和四个ABS运动段，其中三个进一步细分为两个椎体（VB）及其椎间盘（IVD）。所有段均以0.6 mm·min的速度轴向加载^-1（应变率范围6×10 ^-4 s ^-1 –10×10 ^-4 s ^-1）。人造VB的行为类似于弹性区域内的生物片段，但最好的两部分人造IVD的硬度比生物IVD低约15％。在压缩加载过程中记录的高速图像允许产生全场应变。在脊柱运动节段的压缩过程中，IVD比预期的VB承受更高的应变。我们的方法可以快速，廉价和可靠地生产患者专用的3D打印类似物，这些类似物在形态上与真实的相似，并且其机械行为与真实的生物脊柱运动段相当，这是它们的最大资产。