Ganbat Danaa, Kim Kyungsoo, Jin Yong Jun, Kim Yoon Hyuk
Department of Mechanical Engineering, Kyung Hee University, Yongin, Korea.
Proc Inst Mech Eng H. 2014 Feb;228(2):200-5. doi: 10.1177/0954411914522024. Epub 2014 Jan 29.
Heterotopic ossification is one of the possible complications following cervical total disk replacement. Although there are numerous hypotheses regarding the etiology of heterotopic ossification, the main causes of heterotopic ossification remain unknown. In this study, we hypothesize that heterotopic ossification formation is related to external loading in the cervical vertebrae after total disk replacement. A two-dimensional finite element model of a cervical vertebra treated by total disk replacement in the sagittal plane was developed. The bone adaptation process of heterotopic ossification was simulated based on strain energy density under both compressive and shear forces. Different types of heterotopic ossification formation were analyzed according to the directions of forces. Two distinct types of heterotopic ossification following cervical total disk replacement were predicted, which was consistent with previous clinical studies. Type 1 heterotopic ossification was observed in the posterior upper part of the vertebra under compressive forces, while type 2 heterotopic ossification was detected mostly in the anterior upper part under shear forces. In addition, heterotopic ossification formation enhanced the strain energy distribution, which is known to be related to bone remodeling. This article presents the effects of different mechanical loading conditions on the occurrence of heterotopic ossification following cervical total disk replacement, and the results may be useful for the design of artificial disks that minimize heterotopic ossification.
异位骨化是颈椎全椎间盘置换术后可能出现的并发症之一。尽管关于异位骨化的病因有众多假说，但异位骨化的主要原因仍不明确。在本研究中，我们假设异位骨化的形成与全椎间盘置换术后颈椎的外部负荷有关。建立了一个在矢状面行全椎间盘置换的颈椎二维有限元模型。基于压缩力和剪切力作用下的应变能密度模拟了异位骨化的骨适应过程。根据力的方向分析了不同类型的异位骨化形成情况。预测了颈椎全椎间盘置换术后两种不同类型的异位骨化，这与先前的临床研究一致。在压缩力作用下，在椎体后上部观察到1型异位骨化，而在剪切力作用下，2型异位骨化大多出现在椎体前上部。此外，异位骨化的形成增强了应变能分布，而应变能分布已知与骨重塑有关。本文介绍了不同机械负荷条件对颈椎全椎间盘置换术后异位骨化发生的影响，其结果可能有助于设计能使异位骨化最小化的人工椎间盘。
