动态四维CT应用于负荷下腕关节不稳定的生物力学研究

Recently, many studies have emphasized the importance of the comprehension of functional anatomy and biomechanics of the wrist joint and its significant contribution in facilitating good functional outcomes of treatment in the field of wrist disorders. Although the functional anatomy of the wrist joint has been investigated, current information was most based on the cadaveric studies and less information of after load applied can be available. However, no information is available regarding the wrist kinetics under the lateral load and ideal ligament reconstruction treatment for wrist instability remains controversial. We recently found lateral load applied has an effect on the separation of the palmar and dorsal insertions of the scapholunate interosseus ligament (SLIL). The palmar subregion of SLIL was more highly strained with wrist resisted ulnar inclination. On the contrary, the dorsal subregion of SLIL was under much greater tension with wrist resisted radial inclination. That means for patients with conservative treatment of SLIL tears, early isometric training of wrist actively ulnar or radial inclination against resistance may be harmful for SLIL instability, and should be avoided.There are "SL-friendly" muscles and "SL-unfriendly" muscles around the wrist. The project intends to in vivo use dynamic four-dimensional computed tomography (4D CT) reconstruction techniques to investigate the biomechanics of the wrist under load applied. We prepare to recruit 12 adult healthy volunteers, and use Mimics software to reconstruct the 3D image. We select SLIL and lunotriquetral interosseous ligament (LTIL). The subregions of the palmar, dorsal and proximal SLIL and LTIL were defined according to their bone attachments. We calculate changes in lengths of these 6 ligaments during wrist flexion-extension, radioulnar deviation, and dart-thrower’s motion. Then we measure the motion of carpal bone relative to the ulnar and radius using the centroid of the bone and principal inertia axis orientation. In the radius, we defined the Y-axis as the line parallel to the bone shaft. We defined the Z-axis as the line through styloid process of the radius, on the plane perpendicular to the Y-axis. Finally, we defined the X-axis as the lien perpendicular to the YZ plane. We further investigate the biomechanics changes of the motion of the wrist joint under load applied of wrist instability of pre-operation and post-operation. The purpose of this study is to investigate the biomechanics of the normal physiological and pathological state of wrist joint under the load applied in vivo, and to make a systematic exposition of the kinematics characteristics of the joint and ligaments, and to clarify the biomechanics changes of pathological wrist instability. The project can provide important reference value to the pathological basic research, prevention to wrist instability, but also for ligament reconstruction surgery, wrist limited fusion surgery. It can also provide an important theoretical basis on the treatment of the wrist ligament injury, wrist instability and postoperative rehabilitation treatment.

功能解剖和生物力学是关节疾病诊治的基础，也是近年来腕关节外科的研究重点。我们前期研究表明腕关节在抗阻力尺桡偏时，舟月韧带的不同束组张力发生规律的变化，提示腕部周围存在：舟月韧带“友好”肌群及“不友好”肌群。本项目拟对活动的腕关节施加外在负荷，采用动态四维CT扫描，获得实时三维图像，测量腕骨间韧带距离变化，然后通过测量尺、桡骨和每个腕骨的体积、质心位置和主惯性轴方位，研究各腕骨空间位移变化；进一步研究韧带动态转位重建治疗舟月韧带、月三角韧带损伤的腕关节不稳定的可行性，并检测治疗前后腕关节的生物力学情况。通过研究负荷下正常及病理状态下的腕关节运动生物力学，系统阐述腕关节在实际运动过程中运动生物力学变化特点，以及腕关节不稳定运动力学的改变规律。本项目能为腕关节不稳定的病理基础研究及预防提供重要的参考价值，还能为韧带动态转位重建、腕关节融合术治疗腕关节不稳定，以及术后的康复治疗提供重要的指导建议。

腕关节极其复杂，在日常生活中发挥重要作用，众多腕骨及关节周围韧带参与腕关节组成，在腕关节活动中起到支撑稳定作用。腕关节组成骨、周围韧带、或者软组织发生病变，引起腕关节疼痛、腕关节不稳定或者活动受限，会影响腕关节正常活动，严重者会导致腕关节活动明显障碍。因此了解腕关节韧带正常解剖结构及其在关节活动过程中的变化，对研究腕关节活动过程中的生物力学存在一定帮助，对创伤造成腕关节不稳定诊断治疗存在重要价值。临床上我们发现许多腕关节不稳定与腕关节负荷下的尺桡偏运动具有相关性，因此我们模拟出接近损伤状态下腕关节负荷的模型。我们发现，负荷下腕关节进行尺偏运动时，舟月韧带的近侧部分长度显著减小，掌背侧长度没有明显改变。月三角韧带的掌侧部分随着尺偏角增大而缩小，近侧及背侧部的长度未发现明显变化趋势。这一状态说明舟月韧带的掌背侧部分及月三角韧带的近背侧部分在维持舟月骨间间隙、月三角骨间间隙中起重要作用。同时临床上发现骨间膜的损伤与患者腕关节活动及前臂旋转活动度具有相关性。我们对志愿者前臂的最大旋前，旋前45°，中立位，旋后45°，最大旋后位进行前臂CT扫描，测量前臂骨间膜长度的变化。我们发现DOB在中立位变得紧绷，而CBP，几乎是等长的。说明，DOB可能为远端尺桡关节提供主要的稳定作用，而CBP在前臂旋转过程中起到稳定作用。