人工腰椎间盘置换术后上位关节突关节内应力变化的研究

目的　研究人工腰椎间盘置换术对上位相邻节段关节突关节内应力（FS）的影响，并与腰椎融合术进行比较，为人工腰椎间盘的临床应用提供理论依据。 方法　选取6具新鲜成人尸体的腰骶段（L2~S1）标本，将每具标本依次制作成L4/5椎间盘完整（对照组）、L4/5椎间盘置换和L4/5椎间融合模型，并依次进行生物力学实验，将压力传感器置入L3/4关节突关节，以400 N的恒定轴向载荷，±7.5 Nm的力矩模拟生理状态下轴向、后伸和左右侧弯4种运动，分别测量3种模型在各种运动下L3/4关节突关节内压力。 结果　在模拟生理载荷的各种运动下，人工椎间盘置换组与椎间盘完整组相比较，上位关节突关节内压力差异无统计学意义（P＞0.05），而腰椎间融合组相对于椎间盘完整组和人工椎间盘置换组，上位关节突关节内压力均显著增加，差异具有统计学意义（P＜0.05）。 结论 人工腰椎间盘置换术后，上位相邻节段关节突关节内压力与正常腰椎相比无明显改变，而腰椎间融合术后，上位相邻节段关节突关节内压力则显著增加。

Stress changes in superior facet joint after artificial lumbar disc replacement

Objective　To study the stress change of the superior facet joint after artificial disc replacement, compare the result with spinal fusion and provide theoretical evidences for ADR in clinical treatment.　Methods　A total of six fresh human cadaveric lumbosacral spines (L2-S1) were used in this investigation. Each specimen was prepared to three models: intact spine, artificial disc replacement in L4/5 and spinal fusion in L4/5. The specimens were reconstructed by total disc replacement in L4/5 before spinal fusion. A stress sensor was implanted in L3/4 facet joint and the stress was measured under axial rotation, extension and lateral bending, with pure, unconstrained moments(±7.5Nm).　Results　Under simulated-physiological loading conditions, compared with the intact condition, stress in superior facet joint was similar with that of the ADR condition and the difference was insignificant (P＞0.05). However,  stress in superior facet joint was remarkably increased after spinal fusion compared with the intact condition and the ADR condition（P＜0.05）.　Conclusion　The stress of superior facet joint was well maintained after artificial disc replacement, and remarkably increased after spinal fusion.