Li Guoan, Wan Lu, Kozanek Michal
Bioengineering Lab, Department of Orthopaedic Surgery, Massachusetts General Hospital/Harvard Medical School, Boston, MA, USA.
J Biomech. 2008;41(1):128-36. doi: 10.1016/j.jbiomech.2007.07.006. Epub 2007 Aug 13.
The knowledge of real-time in-vivo cartilage deformation is important for understanding of cartilage function and biomechanical factors that may relate to cartilage degeneration. This study investigated cartilage contact area and peak contact compressive strain of four healthy human ankle joints as a function of time using a combined magnetic resonance (MR) and dual-orthogonal fluoroscopic imaging technique. Each ankle was subjected to a different constant loading (between 700 and 820 N). The cartilage contact deformation was obtained from the first second to 300 s after the load was applied. In all ankle joints studied in this paper, contact strains increased to 24-38% at first 20 s after loading. Beyond 20 s, the change of cartilage contact deformation was relatively small and varied in a rate close to zero beyond 50 s. These data indicated that the cartilage contact areas and contact strain could raise dramatically right after loading and reach a relatively stable condition within 1 min after constant loading. The history of cartilage deformation determined in this study may provide a real-time boundary condition for 3D finite element simulation of in vivo cartilage contact stress in the joint as a function of time.
了解实时体内软骨变形对于理解软骨功能以及可能与软骨退变相关的生物力学因素至关重要。本研究使用磁共振（MR）和双正交荧光透视成像技术相结合的方法，研究了四个健康人体踝关节的软骨接触面积和峰值接触压缩应变随时间的变化情况。每个踝关节承受不同的恒定负荷（700至820牛之间）。在施加负荷后的第1秒至300秒内获取软骨接触变形情况。在本文研究的所有踝关节中，接触应变在加载后的最初20秒内增加到24%至38%。超过20秒后，软骨接触变形的变化相对较小，在50秒后变化率接近零。这些数据表明，软骨接触面积和接触应变在加载后会立即显著增加，并在恒定负荷后1分钟内达到相对稳定的状态。本研究确定的软骨变形历史可为关节体内软骨接触应力随时间变化的三维有限元模拟提供实时边界条件。
