Dmitriev Anton E, Gill Norman W, Kuklo Timothy R, Rosner Michael K
Spine Research Laboratory and Department of Orthopaedics and Rehabilitation, Walter Reed Army Medical Center, PO Box 59037, Washington, DC 20012, USA.
Spine J. 2008 Nov-Dec;8(6):918-25. doi: 10.1016/j.spinee.2007.10.034. Epub 2008 Jan 7.
With lumbar arthroplasty gaining popularity, limited data are available highlighting changes in adjacent-level mechanics after multilevel procedures.
Compare operative- and adjacent-segment range of motion (ROM) and intradiscal pressures (IDPs) after two-level arthroplasty versus circumferential arthrodesis.
Cadaveric biomechanical study.
Ten human cadaveric lumbar spines were used in this investigation. Biomechanical testing was performed according to a hybrid testing protocol using an unconstrained spine simulator under axial rotation (AR), flexion extension (FE), and lateral-bending (LB) loading. Specimens were tested in the following order: 1) Intact, 2) L3-L5 total disc replacement (TDR), 3) L3-L5 anterior interbody cages+pedicle screws. IDP was recorded at proximal and distal adjacent levels and normalized to controls (%intact). Full ROM was monitored at the operative and adjacent levels and reported in degrees.
Kinematics assessment revealed L3-L5 ROM reduction after both reconstructions versus intact controls (p < .05). However, global quality of segmental motion distributed over L2-S1 was preserved in the arthroplasty group but was significantly altered after circumferential fixation. Furthermore, adjacent-level ROM was increased for the arthrodesis group under LB at both segments and during AR at L2-L3 relative to controls (p < .05). FE did not reveal any intergroup statistical differences. Nonetheless, after arthrodesis IDPs were increased proximally under all three loading modalities, whereas distally a significant IDP rise was noted during AR and LB (p < .05). No statistical differences in either biomechanical parameter were recorded at the adjacent levels between intact control and TDR groups.
Our results indicate no significant adjacent-level biomechanical changes between arthroplasty and control groups. In contrast, significant alterations in ROM and IDP were recorded both proximally (ROM=LB & AR; IDP=AR, FE, LB) and distally (ROM=LB; IDP=AR & LB) after circumferential arthrodesis. Therefore, two-level lumbar arthroplasty maintains a more favorable biomechanical environment at the adjacent segments compared with the conventional transpedicular fixation technique. This, in turn, may have a positive effect on the rate of the transition syndrome postoperatively.
随着腰椎置换术越来越受欢迎，关于多节段手术相邻节段力学变化的数据有限。
比较两级置换术与环形融合术后手术节段及相邻节段的活动范围（ROM）和椎间盘内压力（IDP）。
尸体生物力学研究。
本研究使用了10具人类尸体腰椎。根据混合测试方案，在轴向旋转（AR）、屈伸（FE）和侧屈（LB）负荷下，使用无约束脊柱模拟器进行生物力学测试。标本按以下顺序进行测试：1）完整状态，2）L3-L5全椎间盘置换（TDR），3）L3-L5前路椎间融合器+椎弓根螺钉。在近端和远端相邻节段记录IDP，并将其标准化为对照组（%完整状态）。在手术节段和相邻节段监测全ROM，并以度数报告。
运动学评估显示，与完整对照组相比，两种重建术后L3-L5的ROM均降低（p < 0.05）。然而，置换术组L2-S节段的节段性运动整体质量得以保留，但环形固定后显著改变。此外，与对照组相比，融合术组在两个节段的LB以及L2-L3的AR过程中相邻节段的ROM增加（p < 0.05）。FE未显示任何组间统计学差异。尽管如此，融合术后，在所有三种负荷模式下近端的IDP均增加，而在AR和LB过程中远端的IDP显著升高（p < 0.05）。完整对照组和TDR组在相邻节段的任何生物力学参数上均未记录到统计学差异。
我们的结果表明，置换术组与对照组之间相邻节段的生物力学变化不显著。相比之下，环形融合术后近端（ROM=LB和AR；IDP=AR、FE、LB）和远端（ROM=LB；IDP=AR和LB）的ROM和IDP均有显著改变。因此，与传统的经椎弓根固定技术相比，两级腰椎置换术在相邻节段维持了更有利的生物力学环境。这反过来可能对术后过渡综合征的发生率产生积极影响。
