Institute of Orthopaedic Research and Biomechanics, Center of Musculoskeletal Research, University of Ulm, Helmholtzstrasse 14, 89081 Ulm, Germany.
J Mech Behav Biomed Mater. 2012 Oct;14:67-77. doi: 10.1016/j.jmbbm.2012.05.010. Epub 2012 May 26.
Hydrogels are considered promising for disc regeneration strategies. However, it is currently unknown whether the destruction of the natural interface between nucleus and surrounding structures caused by nucleotomy and an inadequate annulus closure diminishes the mechanical competence of the disc. This in vitro study aimed to clarify these mechanisms and to evaluate whether hydrogels are able to restore the biomechanical behaviour of the disc. Nucleus pressure in an ovine intervertebral disc was measured in vivo during day and night and adapted to an in vitro axial compressive diurnal (15min) and night (30min) load. Effects of different defects on disc height and nucleus pressure were subsequently measured in vitro using 30 ovine motion segments. Following cases were considered: intact; annulus incision repaired by suture and glue; annulus incision with removal and re-implantation of nucleus tissue; and two different hydrogels repaired by suture and glue. The intradiscal pressure in vivo was 0.75MPa during day and 0.5MPa during night corresponding to an in vitro axial compressive force of 130 and 58N, respectively. The compression test showed that neither the implantation of hydrogels nor the re-implantation of the natural nucleus, assumed as being the ideal implant, was able to restore the mechanical functionality of an intact disc. Results indicate the importance of the natural anchorage of the nucleus with its surrounding structures and the relevance of an appropriate annulus closure. Therefore, hydrogels that are able to mimic the mechanical behaviour of the native nucleus may fail in restoring the mechanical behaviour of the disc.
水凝胶被认为是有前途的椎间盘再生策略。然而，目前尚不清楚核切术和环不充分闭合破坏核与周围结构之间的天然界面是否会降低椎间盘的机械性能。这项体外研究旨在阐明这些机制，并评估水凝胶是否能够恢复椎间盘的生物力学行为。在体内测量了绵羊椎间盘的核内压力，白天和夜间均进行测量，并适应体外轴向压缩日（15 分钟）和夜（30 分钟）负荷。随后在体外使用 30 个绵羊运动节段测量了不同缺陷对椎间盘高度和核内压力的影响。考虑了以下情况：完整；通过缝线和胶水修复的环切开；环切开并切除和重新植入核组织；以及两种不同的通过缝线和胶水修复的水凝胶。体内椎间盘内压力白天为 0.75MPa，夜间为 0.5MPa，相应的体外轴向压缩力分别为 130N 和 58N。压缩试验表明，水凝胶的植入或天然核的再植入，即使假设为理想植入物，都无法恢复完整椎间盘的机械功能。结果表明，核与其周围结构的天然锚定的重要性以及环适当闭合的相关性。因此，能够模拟天然核机械行为的水凝胶可能无法恢复椎间盘的机械行为。
