Spine Research Laboratory, Department of Neurosurgery, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA.
Neurosurg Focus. 2010 Jun;28(6):E9. doi: 10.3171/2010.3.FOCUS1046.
The goal of this study was to evaluate and compare load sharing of the facet and uncovertebral joints after total cervical disc arthroplasty using 3 different implant designs.
Three-dimensional voxel finite element models were built for the C5-6 spine unit based on CT images acquired from a candidate patient for cervical disc arthroplasty. Models of facet and uncovertebral joints were added and artificial discs were placed in the intervertebral disc space. Finite element analyses were conducted under normal physiological loads for flexion, extension, and lateral bending to evaluate von Mises stresses and strain energy density (SED) levels at the joints.
The Bryan disc imposed the greatest average stress and SED levels at facet and uncovertebral joints with flexion-extension and lateral bending, while the ProDisc-C and Prestige LP discs transferred less load due to their rigid cores. However, all artificial discs showed increased loads at the joints in lateral bending, which may be attributed to direct impinging contact force.
In unconstrained/semiconstrained prostheses with different core rigidity, the shared loads at the joints differ, and greater flexibility may result in greater joint loads. With respect to the 3 artificial discs studied, load sharing of the Bryan disc was highest and was closest to normal load sharing with the facet and uncovertebral joints. The Prestige LP and ProDisc-C carried more load through their rigid core, resulting in decreased load transmission to the facet and uncovertebral joints.
本研究旨在评估和比较三种不同假体设计在全颈椎间盘置换术后对小关节突关节和钩椎关节的负荷分担。
根据颈椎间盘置换术候选患者的 CT 图像，建立 C5-6 脊柱单元的三维体素有限元模型。添加小关节突关节和钩椎关节模型，并在椎间盘间隙放置人工椎间盘。在正常生理负荷下进行屈伸和侧屈的有限元分析，以评估关节处的 von Mises 应力和应变能密度（SED）水平。
Bryan 椎间盘在屈伸和侧屈时对小关节突关节和钩椎关节施加的平均应力和 SED 水平最大，而 ProDisc-C 和 Prestige LP 椎间盘由于其刚性核心传递的负荷较小。然而，所有人工椎间盘在侧屈时关节处的负荷均增加，这可能归因于直接撞击接触力。
在具有不同核心刚性的非约束/半约束假体中，关节的分担负荷不同，更大的灵活性可能导致更大的关节负荷。就所研究的三种人工椎间盘而言，Bryan 椎间盘的分担负荷最高，与小关节突关节和钩椎关节的正常负荷分担最为接近。Prestige LP 和 ProDisc-C 通过其刚性核心承载更多的负荷，导致向小关节突关节和钩椎关节的负荷传递减少。
