Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy.
Research and Development Service, Stratton VA Medical Center, Albany, NY.
Spine (Phila Pa 1976). 2018 Sep 15;43(18):E1061-E1068. doi: 10.1097/BRS.0000000000002643.
In vitro biomechanical testing of human cadaveric cervical and goat cervical motion segments.
The aim of this study was to measure the effects of plate stiffness on load-sharing, instantaneous axis of rotation (IAR), and posterior element loading after anterior cervical discectomy and fusion (ACDF).
ACDF is intended to create an environment, which facilitates sufficient stability and biomechanical conditions to promote bone formation. The relationship between cervical plate stiffness, load-sharing, and the IAR is complex. The ideal cervical plate is sufficiently stiff to limit interbody motion but is compliant enough to facilitate load-sharing rather than stress-shielding.
Anterior cervical plates of distinct bending stiffnesses were applied to human and goat cervical motion segments following ACDF. A validated custom force-sensing interbody implant was placed in the disc space to measure load-sharing in the spine. Interbody loads, posterior element strain, and the IAR were measured during flexion/extension for each plate.
Load-sharing in the interbody space, posterior element strain, and the location of the IAR were all significantly affected by plate stiffness. More compliant plates resulted in more load sharing, less posterior element strain, and a more dorsally located IAR relative to stiffer plates.
A more compliant plate fosters more consistent load-sharing through the entire range of flexion/extension, which may promote faster bone formation and better fusion. A more compliant plate causes less posterior element strain, which may reduce facet joint loads and in turn reduce facet joint arthrosis. An ideal plate may be one that is stiff enough to minimize interbody motion and yet compliant enough to allow consistent load-sharing and minimal increase in posterior element strain.
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人尸体颈椎和山羊颈椎运动节段的体外生物力学测试。
本研究旨在测量钢板刚度对颈椎前路椎间盘切除融合术（ACDF）后负荷分担、瞬时旋转轴（IAR）和后节段加载的影响。
ACDF 的目的是创造一个环境，促进骨形成所需的稳定性和生物力学条件。颈椎板刚度、负荷分担和 IAR 之间的关系非常复杂。理想的颈椎板应足够硬以限制椎间运动，但应具有足够的顺应性以促进负荷分担而不是应力屏蔽。
在 ACDF 后，将不同弯曲刚度的颈椎前路钢板应用于人及山羊颈椎运动节段。将经过验证的定制力感应椎间植入物放置在椎间盘间隙内，以测量脊柱的负荷分担。在每个钢板的屈伸过程中测量椎间负荷、后节段应变和 IAR。
椎间盘空间的负荷分担、后节段应变和 IAR 的位置均受到钢板刚度的显著影响。更顺应性的钢板导致更多的负荷分担、更少的后节段应变和 IAR 更位于背侧，与更刚性的钢板相比。
更顺应性的钢板通过整个屈伸范围促进更一致的负荷分担，这可能促进更快的骨形成和更好的融合。更顺应性的钢板导致更少的后节段应变，这可能减少关节突关节负荷，从而减少关节突关节关节炎。理想的钢板可能是一种既足够硬以最小化椎间运动，又足够顺应以允许一致的负荷分担和最小的后节段应变增加的钢板。
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