New methods for assessing hip biomechanics.

完整而准确地了解人类髋关节的生物力学对于理解其功能和设计影响这一重要关节的疾病的治疗方法至关重要。**研究髋关节力学的一个主要障碍是关节内有一层流体，关节被一种称为髋臼唇的结构密封。因此，不可能通过在关节中引入传感器来测量关节接触力、应变分布或压力，因为这会破坏密封并改变接触力学。这使得基于成像的方法来研究髋关节力学至关重要。**本研究项目的长期目标是发展评估生理条件下髋关节力学的方法，并应用这些方法综合确定最常见的髋关节畸形和损伤如何改变髋关节力学，以及哪种治疗方法最有效地恢复髋关节力学正常。**在这个项目中，两个短期目标是：**在目标1中，我们将开发基于成像的方法来测量装载在尸体标本中的髋关节软骨应变，以模拟体内生理负荷。为了使测量比以往任何测量都更准确，我们将使用加拿大光源同步加速器对臀部进行三维计算机断层成像。为了实现同步加速器成像来测量生理负荷的尸体髋关节软骨应变，我们将开发：*a)在同步加速器成像区域内的生理负荷水平和生理位置加载尸体髋关节的系统；*b)实现造影剂在软骨内充分扩散的方案；*c)图像处理，确定软骨变形和应变；*d)在5个尸体髋关节标本中量化该方法重复性的实验***在Aim 2中，我们将确定一种常见的髋关节畸形，股髋臼撞击（FAI）和髋臼唇损伤对髋关节标本在生理负荷和髋关节位置下软骨应变的影响。我们将获得10个记录有凸轮畸形的尸体髋关节标本，作为对照组，10个通过x光片和CT扫描证实没有畸形或其他病理的标本。我们将把每个标本置于生理位置，包括那些可能导致撞击的位置，并使用同步加速器成像评估髋臼和股软骨的应变，如Aim 1所述。这将在髋臼唇切除术后重复。我们将比较正常髋关节和FAI髋关节之间的最大应变、平均应变和最大应变的位置，以及完整的唇形和切除的唇形状态之间的最大应变，以评估FAI畸形和唇形对软骨压缩应变的影响。**一旦这种新方法被开发出来，它将成为进一步研究髋关节的基础，包括髋臼唇等其他组织的机械行为，以及评估其他髋关节疾病和治疗对髋关节力学的影响。

A complete and accurate understanding of the biomechanics of the human hip is essential for understanding its function and for designing treatments for disorders that affect this vital joint. **A primary obstacle to studying hip mechanics is that there is a fluid layer within the joint, and the joint is sealed by a structure known as the acetabular labrum. Consequently, it is not possible to measure joint contact force, strain distribution or pressure by introducing a sensor into the joint because this would violate the seal and change the contact mechanics. This makes an imaging-based approach to studying hip mechanics essential. **The long-term objectives of this program of research are to develop methods to assess hip mechanics under physiological conditions and to apply these methods to determine comprehensively how the most prevalent hip deformities and injuries change hip mechanics, and which treatment approaches most effectively restore hip mechanics to normal. **Within this program, two short-term objectives are: **In Aim 1, we will develop imaging-based methods for measuring cartilage strain in the hip joint in cadaver specimens loaded to simulate in vivo physiological loads. To make measurements that are more accurate than any that have been made previously, we will use the Canada Light Source synchrotron to perform three dimensional, computed tomography images of hips. To implement synchrotron imaging for measuring cartilage strain in physiologically loaded cadaver hips we will develop:*a) a system for loading cadaver hip joints at physiological levels of load and at physiological positions within the imaging area of the synchrotron; *b) a protocol for achieving full diffusion of contrast agent into the cartilage; *c) image processing for determining cartilage deformation and strain; *d) experiments quantifying the reproducibility of the method in five cadaver hip specimens***In Aim 2 we will determine the effect of a prevalent type of hip deformity, femoroacetabular impingement (FAI), and acetabular labral damage on cartilage strain in hip specimens at physiological loads and hip positions. We will obtain ten cadaver hip specimens with documented cam deformities and, for the control group, ten specimens confirmed, by radiographs and CT scans, to have no deformities or other pathology. We will load each specimen in physiological positions, including those expected to lead to impingement, and assess strain in the acetabular and femoral cartilage using synchrotron imaging as described in Aim 1. This will be repeated after resection of the acetabular labrum. We will compare maximum strain, mean strain and the location of maximum strain between normal and FAI hips, and between the intact labrum and resected labrum states to assess the effects of FAI deformity and the labrum on compressive cartilage strain. **Once this new method is developed, it will form the basis for further studies of the hip, including the mechanical behaviour of other tissues such as the acetabular labrum, and assessments of the effects of other hip disorders and treatments on hip mechanics.