负荷下生理及病理肘关节生物力学研究

Knowledge of elbow biomechanics and functional anatomy of the elbow is very important. Recently, many studies have emphasized the importance of the comprehension of functional anatomy and biomechanics of the elbow and its significant contribution in facilitating good functional outcomes of treatment in the field of elbows disorders. Although the functional anatomy of the elbow joint has been investigated, current information was most based on the cadaveric studies and less information of after load applied can be available. Lateral epicondylitis is a familiar term used to explain the numerous symptoms in the vicinity of the lateral aspect of the elbow. Heterotopic ossification is a known consequence or complication of the management of traumatic elbow injuries, especially intra-articular fractures and fracture-dislocation. However, the etiologies include secondary intra-articular elbow lesion, and ideal treatment remains controversial. We recently found during the elbow flexion, the tension of collateral ligaments increased to some extents, compared with the position of elbow full extension, and changes of the tension of the collateral ligaments showed certain regularity, which suggesting possible to find the ideal ligament reconstruction center. The project intends to in vivo use three-dimensional computed tomography (CT) reconstruction techniques to investigate the biomechanics of the elbow under load applied. We prepare to recruit 12 adult healthy volunteers, and use Mimics software to reconstruct the 3D image. We select two ligament paths consisting of the anterior bundle of the medial collateral ligament (AMCL) and the lateral ulnar collateral ligament (LUCL). The AMCL and LUCL are subdivided into 3 ligaments, respectively. We calculate changes in lengths of these 6 ligaments during elbow flexion-extension and forearm rotation (supination to pronation) with measurement the distance between the ligament footprints. Then import the 3D CT image into magics software and measure the contact area of the radiocarpitellar joint proximal radioulnar joint and ulnohumeral joint using the expansion theory. And we measure the motion of ulnar and radius relative to the humerus using the centroid of the bone and principal inertia axis orientation. In the humerus, we defined the Y-axis as the line parallel to the bone shaft. We defined the Z-axis as the line through the lateral epicondyle 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 elbow joint under load applied of the lateral epicondylitis and elbow posttraumatic osteoarthritis. The purpose of this study is to investigate the biomechanics of the normal physiological and pathological state of elbow joint under the load applied in vivo, and to make a systematic exposition of the kinematics characteristics of the joint and collateral ligaments, and to clarify the biomechanics changes of pathological elbow. The project can provide important reference value to the pathological basic research, prevention and treatment to lateral epicondylitis and posttraumatic osteoarthritis, but also for ligament reconstruction surgery, elbow joint prosthesis design and replacement. It can also provide an important theoretical basis on the treatment of the elbow ligament injury, elbow instability and postoperative rehabilitation treatment.

功能解剖和生物力学是关节疾病诊治的基础，也是近年来肘关节外科的研究重点。我们前期研究表明肘关节在屈伸过程中，侧副韧带张力有规律的变化，提示可能找到理想的韧带重建中心。本项目拟对负荷下运动的肘关节进行CT扫描，采用MIMICS软件重建三维图像，测量韧带足迹距离的变化，然后将三维CT图像导入Magics软件，利用“膨胀理论”测量关节接触面积的变化，并通过测量尺桡骨质心位置和主惯量轴方位，研究尺桡骨相对于肱骨空间位移变化；进一步研究肱骨外上髁炎和肘骨性关节炎患者，在外力负荷下肘关节活动的生物力学情况。通过研究负荷下正常及病理状态下的肘关节运动生物力学，系统阐述在实际运动过程中肘关节及侧副韧带运动学变化特点，以及病理肘关节运动力学的改变规律。本项目能为肱骨外上髁炎及骨关节炎的病理基础研究、预防及治疗提供重要的参考价值，还能为韧带重建手术、肘关节假体设计及置换，以及术后的康复治疗提供重要的理论基础。

肘关节极其复杂，在日常生活、以及诸多体育活动中发挥着重要的作用。肘关节组成骨、周围韧带、或者软组织发生病变，引起肘关节疼痛、肘关节不稳定或者活动受限，会影响肘关节正常活动，严重者会导致肘关节活动明显障碍，一些优秀运动员的运动生涯因此而终结。但与肩、腕、膝及髋等其它关节相比，对肘关节研究的深度和广度仍显不足，在我国这方面的研究工作尤其薄弱。临床上我们发现许多肘关节的骨折和韧带损伤情况与患者摔倒时肘关的位置具有相关性，于是我们对于肘关节损伤力学机制的探究，模拟出接近损伤状态下肘关节轴向负荷的模型。受力状态下肘关节会通过旋前旋后来缓冲轴向负荷已到达应力分散的状态进而进一步对周围的稳定结构产生冲击，造成韧带损伤。整个动态过程中韧带变化方面，我们发现肘关节内侧副韧带的前束的内侧及中央部无论是有无负荷状态下在前臂旋前到旋后的变化中明显缩短，而外侧副韧带无论是有无负荷状态下长度基本处于静止状态。这一现象告诉我们前臂旋负荷状态下，内侧副韧带常常容易损伤，这一状态下的受伤提示我们临床医生不能遗漏内侧副韧带的相关检查。关节接触方面，我们发现轴向负荷增加肘关节的肱桡关节接触面积在旋前位为8.6%、旋后位为10.5%。无负荷状态下旋前到旋后位,接触中心向前内侧移动2.4mm,相比旋前无负荷状态下，负荷使得接触中心向桡骨小头的中央移动了1mm. 负荷状态下旋前到旋后位,接触中心向前内侧移动2.4mm。旋前到旋后位增加桡骨小头结节前缘的接触面在无负荷状态下为14%、负荷状态下为8%。。这一现象告诉我们负荷是引起肱桡关节面骨折的重要原因，从旋前到旋后状态下桡骨小头前缘骨折的几率大大增加，这一特性也为肱桡关节假体的设计提供参考。

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