Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland; Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
Radiology, Balgrist University Hospital, Zurich, Switzerland.
Spine J. 2021 Aug;21(8):1399-1407. doi: 10.1016/j.spinee.2021.04.016. Epub 2021 Apr 24.
The ligamentum flavum (LF), the inter- and supraspinous ligament (ISL&SSL) and the intertransverse ligament (ITL) are relevant spinal structures for segmental stability. The biomechanical effect of degeneration and aging on their biomechanical properties remains largely unknown.
The aim of this study was to assess the material properties of the ITL, ISL&SSL and LF and to correlate parameters of biomechanical function with LF-thickness, intervertebral disc (IVD) degeneration and age.
Biomechanical cadaveric study.
MRI- and CT-scans of 50 human lumbar segments (Th12-L5) were used to assess the ISL (acc. to Keorochana), the grade of IVD degeneration (acc. to Pfirrmann) and to quantify LF-thickness. The ITL, ISL&SSL and LF were resected in the neutral position of the spinal segment with a specifically developed method to conserve initial strain. Ramp to failure testing was performed (0.5 mm/s) to record initial tension, slack length, stiffness and ultimate strength. The relationship between the biomechanical characteristics and age and radiological parameters were analyzed. There are no study-specific conflicts of interest and no external funding was received for this study.
With aging, a significant reduction in initial tension (r=-0.5, p<.01) and ultimate strength (r=-0.41, p<.01) of the LF was observed, while the effect on LF-stiffness and the characteristics of the other ligaments was non-significant. IVD-degeneration was correlated with a significant reduction in stiffness (r=-0.47, p=.001; r=-0.36, p=.01) and ultimate strength (r=-0.3, p=.04; r=-0.36, p=.01) of the LF and ISL&SSL respectively and a significant reduction in initial tension (r=-0.4, p<.01) of the LF. For the ITL, no significant correlation was observed. Comparing Pfirrman 2 to 5, this reduction was 40% to 80% for stiffness 60% to 70% for ultimate strength and 88% for initial tension of the LF. ISL&SSL-stiffness between Kerorochana grade A and D differed significantly (p=.03), while all other comparisons were non-significant (p>.05). LF-thickness did not correlate with the biomechanical properties of the LF (p>.05).
Aging is primarily related to biomechanical changes to the LF. IVD-degeneration is related to a relevant reduction in stiffness and ultimate strength of the LF and ISL&SSL, with a similar trend for the ITL. The ISL-specific Keorochana grading system provides only minimal biomechanical information and LF-thickness does not provide biomechanical information.
Patient age and the degenerative state of the IVD can be used to evaluate the biomechanical characteristics of the dorsal spinal ligaments, which can be helpful in selecting the optimal surgical procedure (e.g. in decompression surgery) for a specific situation.
黄韧带（LF）、棘间韧带（ISL 和 SSL）和横突间韧带（ITL）是与节段稳定性相关的脊柱结构。其生物力学特性随退变和老化而变化的情况在很大程度上尚不清楚。
本研究旨在评估 ITL、ISL 和 SSL 以及 LF 的材料特性，并将生物力学功能的参数与 LF 厚度、椎间盘（IVD）退变和年龄相关联。
生物力学尸体研究。
使用 50 个人类腰椎节段（Th12-L5）的 MRI 和 CT 扫描，评估 ISL（根据 Keorochana）、IVD 退变程度（根据 Pfirrmann）和 LF 厚度。使用专门开发的方法在脊柱节段的中立位置切除 ITL、ISL 和 SSL，以保持初始应变。进行斜坡至失效测试（0.5mm/s）以记录初始张力、松弛长度、刚度和极限强度。分析生物力学特征与年龄和影像学参数之间的关系。本研究无特定的研究相关冲突，也没有收到外部资金支持。
随着年龄的增长，LF 的初始张力（r=-0.5，p<.01）和极限强度（r=-0.41，p<.01）明显降低，而对 LF 刚度和其他韧带特性的影响则不显著。IVD 退变与 LF 和 ISL&SSL 刚度的显著降低（r=-0.47，p=.001；r=-0.36，p=.01）和极限强度（r=-0.3，p=.04；r=-0.36，p=.01）显著相关，LF 的初始张力（r=-0.4，p<.01）也显著降低。对于 ITL，未观察到显著相关性。与 Pfirrman 2 至 5 相比，LF 刚度降低了 40%至 80%，极限强度降低了 60%至 70%，初始张力降低了 88%。ISL&SSL 刚度在 Kerorochana 分级 A 与 D 之间存在显著差异（p=.03），而其他所有比较均无显著差异（p>.05）。LF 厚度与 LF 的生物力学特性无关（p>.05）。
老化主要与 LF 的生物力学变化有关。IVD 退变与 LF 和 ISL&SSL 刚度的显著降低以及 ITL 的相似趋势有关。ISL 特异性的 Keorochana 分级系统仅提供最小的生物力学信息，LF 厚度不提供生物力学信息。
患者年龄和 IVD 的退行性状态可用于评估背侧脊柱韧带的生物力学特性，这有助于为特定情况选择最佳手术方案（例如减压手术）。
