Mo Zhong Jun, Zhao Yan Bin, Wang Li Zhen, Sun Yu, Zhang Ming, Fan Yu Bo
Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Key Laboratory for Optimal Design and Evaluation Technology of Implantable & Interventional Medical Devices, International Joint Research Center of Aerospace Biotechnology and Medical Engineering of Ministry of Science and Technology, School of Biological Science and Medical Engineering, Beihang University, XueYuan Road No.37, HaiDian District, Beijing, 100191, People's Republic of China.
Eur Spine J. 2014 Mar;23(3):613-21. doi: 10.1007/s00586-013-3070-4. Epub 2013 Oct 24.
Various design concepts have been adopted in cervical disc prostheses, including sliding articulation and standalone configuration. This study aimed to evaluate the biomechanical effects of the standalone U-shaped configuration on the cervical spine.
Based on an intact finite element model of C3-C7, a standalone U-shaped implant (DCI) was installed at C5-C6 and compared with a sliding articulation design (Prodisc-C) and an anterior fusion system. The range of motion (ROM), adjacent intradiscal pressure (IDP) and capsular ligament strain were calculated under different spinal motions.
Compared to the intact configuration, the ROM at C5-C6 was reduced by 90% after fusion, but increased by 70% in the Prodisc-C model, while the maximum percentage change in the DCI model was 30% decrease. At the adjacent segments, up to 32% increase in ROM happened after fusion, while up to 34% decrease occurred in Prodisc-C model and 17% decrease in DCI model. The IDP increased by 11.6% after fusion, but decreased by 5.6 and 6.3% in the DCI and Prodisc-C model, respectively. The capsular ligament strain increased by 147% in Prodisc-C and by 13% in the DCI model. The DCI implant exhibited a high stress distribution.
Spinal fusion resulted in compensatory increase of ROM at the adjacent sites, thereby elevating the IDP. Prodisc-C resulted in hyper-mobility at the operative site that led to an increase of ligament force and strain. The U-shaped implant could maintain the spinal kinematics and impose minimum influence on the adjacent soft tissues, despite the standalone configuration encountering the disadvantages of high stress distribution.
颈椎间盘假体采用了多种设计理念，包括滑动关节和独立构型。本研究旨在评估独立U形构型对颈椎的生物力学影响。
基于C3 - C7完整的有限元模型，在C5 - C6处植入独立U形植入物（DCI），并与滑动关节设计（Prodisc - C）和前路融合系统进行比较。计算不同脊柱运动下的活动范围（ROM）、相邻椎间盘内压力（IDP）和关节囊韧带应变。
与完整构型相比，融合后C5 - C6处的ROM降低了90%，但在Prodisc - C模型中增加了70%，而DCI模型中的最大百分比变化是降低了30%。在相邻节段，融合后ROM增加高达32%，而Prodisc - C模型中降低高达34%，DCI模型中降低17%。融合后IDP增加了11.6%，但在DCI和Prodisc - C模型中分别降低了5.6%和6.3%。Prodisc - C模型中关节囊韧带应变增加了147%，DCI模型中增加了13%。DCI植入物表现出高应力分布。
脊柱融合导致相邻部位ROM代偿性增加，从而升高IDP。Prodisc - C导致手术部位活动过度，导致韧带力和应变增加。尽管独立构型存在高应力分布的缺点，但U形植入物可以维持脊柱运动学并对相邻软组织施加最小影响。
