腰骶瞬时旋转中心空间轨迹与节段稳定性控制的研究

The non-fusion technique played an important role in the surgical treatment of lumbosacral degenerative diseases. However, its clinical effectiveness is often limited because of the lack of dynamic biomechanical evaluation system and standards for lumbosacral functional segments, which lead to poor biological simulation with current non-fusion technique. Thus it is unable to meet the need of lumbosacral dynamic activities. The application of computer simulation technology in space can acquire the instantaneous helical center (IHC) of lumbosacral functional segments quantum image describing the pathway of motion. Generally, both healthy man and patients with lumbosacral degeneration have an identical IHC trajectory. Different clinical interventions may alter the IHC trajectory of lumbosacral functional segments. Observing lumbosacral functional activities by static IHC space images, can help us to evaluate efficacy of the surgical treatment, especially the stability of lumbosacral functional segments. In this study, we will firstly measure the space trajectory pattern of lumbar IHC changes under healthy conditions and different pathological conditions; We will also observe the variation of lumbar IHC after different clinical interventions. Furthermore, we will explore the relationship between the fitting degree of the IHC and efficacy of treatment in clinical trials to establish an IHC prediction model. Finally, we will use biomechanical tests to study the control scheme for optimum stability by increasing the fitting degree of IHC. This study would provide new theoretical and clinical basis for the development and design of new spinal non-fusion devices.

非融合技术在腰骶部退变性疾患的手术治疗中具有重要意义。由于目前缺乏对该功能节段稳定性的有效评价体系和标准，现有的腰骶部非融合技术生物仿真度低，难以满足腰骶部动态活动需要，导致其临床疗效明显受限。前期工作中课题组利用计算机软件获得了腰骶部功能节段瞬时旋转中心（IHC）的空间轨迹图，发现正常人群和退变患者均有其特异的IHC轨迹。不同临床干预后的腰骶部可能也会呈现特定的IHC轨迹。我们认为利用在体、动态手段获取的IHC空间轨迹图像，能更有效地评价腰骶椎的稳定性和手术疗效。基于前期的结果，本课题着重探讨：1.测量正常人群和不同病理条件下腰椎IHC空间轨迹变化规律；同时测量不同临床干预情况下腰椎IHC的变化规律；2.通过临床研究，探讨IHC拟合度与临床疗效之间的关系，建立IHC判断模型；3.通过生物力学测试，研究增加IHC拟合度的最佳稳定性控制方案。为制定和设计新型脊柱非融合手术提供理论和临床依据。

非融合技术在腰骶部退变性疾患的手术治疗中具有重要意义。动态固定虽已取得良好的效果，但尚存很多问题有待解决。课题组自行设计一种弹性连接棒，其限制凹侧缝隙的压缩，实现了限制椎间的过度运动并且允许保留一定程度椎间活动的目的。本研究通过有限元分析与生物力学测试，测算了节段失稳模型、皮质骨螺钉常规钛棒固定、Dynesys固定以及新型弹性棒固定下的腰椎稳定性、邻近节段的椎间盘压力、关节突关节面以及钉棒的应力，同时应用有限元分析计算了不同固定方式下腰椎瞬时旋转中心（IHC）的空间轨迹。结果发现应用皮质骨轨迹螺钉动态固定技术，能够使失稳模型获得即刻的稳定性，同时也保留了固定节段的活动能力，能够降低邻近节段的椎间盘应力以及关节突关节的应力，其IHC更加接近正常位置，为避免因术后应力集中导致的邻椎病、内固定失败或断裂等并发症提供理论依据。同时课题组进行了腰椎间盘的蠕变实验，首先制作了包含椎间盘和上下各一半椎体的脊柱功能单元（FSU），对其施加大小不同的应力，观察椎间盘应变，并绘制蠕变曲线，结果发现随着应力的增大，椎间盘的应变程度也逐渐增加，进一步证实了动态固定技术对邻近节段椎间盘的保护作用。