Wu J Z, Herzog W, Epstein M
Department of Mechanical Engineering, Faculty of Engineering, University of Calgary, Alberta, Canada.
J Biomech Eng. 1998 Oct;120(5):655-9. doi: 10.1115/1.2834758.
Fuji film has been widely used in studies aimed at obtaining the contact mechanics of articular joints. Once sealed for practical use in biological joints, Fuji Pressensor film has a total effective thickness of 0.30 mm, which is comparable to the cartilage thickness in the joints of many small animals. The average effective elastic modulus of Fuji film is approximately 100 MPa in compression, which is larger by a factor of 100-300 compared to that of normal articular cartilage. Therefore, inserting a Pressensor film into an articular joint will change the contact mechanics of the joint. The measurement precision of the Pressensor film has been determined systematically; however, the changes in contact mechanics associated with inserting the film into joints have not been investigated. This study was aimed at quantifying the changes in the contact mechanics associated with inserting sealed Fuji Pressensor film into joints. Spherical and cylindrical articular joint contact mechanics with and without Pressensor film and for varying degrees of surface congruency were analyzed and compared by using finite element models. The Pressensor film was taken as linearly elastic and the cartilage was assumed to be biphasic, composed of a linear elastic solid phase and an inviscid fluid phase. The present analyses showed that measurements of the joint contact pressures with Fuji Pressensor film will change the maximum true contact pressures by 10-26 percent depending on the loading, geometry of the joints, and the mechanical properties of cartilage. Considering this effect plus the measurement precision of the film (approximately 10 percent), the measured joint contact pressures in a joint may contain errors as large as 14-28 percent.
富士胶片已广泛应用于旨在获取关节接触力学的研究中。一旦密封以实际用于生物关节，富士压力传感胶片的总有效厚度为0.30毫米，这与许多小型动物关节中的软骨厚度相当。富士胶片在压缩时的平均有效弹性模量约为100兆帕，比正常关节软骨大100 - 300倍。因此，将压力传感胶片插入关节会改变关节的接触力学。压力传感胶片的测量精度已得到系统确定；然而，与将胶片插入关节相关的接触力学变化尚未得到研究。本研究旨在量化与将密封的富士压力传感胶片插入关节相关的接触力学变化。通过使用有限元模型，分析并比较了有和没有压力传感胶片以及不同表面贴合度情况下的球形和圆柱形关节接触力学。压力传感胶片被视为线性弹性材料，软骨被假定为双相材料，由线性弹性固相和无粘性流体相组成。目前的分析表明，使用富士压力传感胶片测量关节接触压力时，根据加载情况、关节几何形状和软骨力学性能，最大真实接触压力会改变10% - 26%。考虑到这种影响以及胶片的测量精度（约10%），关节中测量的关节接触压力可能包含高达14% - 28%的误差。
