Islam Kamrul, Duke Kajsa, Mustafy Tanvir, Adeeb Samer M, Ronsky Janet L, El-Rich Marwan
a Department of Civil and Environmental Engineering , University of Alberta , Edmonton , AB , Canada.
Comput Methods Biomech Biomed Engin. 2015;18(4):391-400. doi: 10.1080/10255842.2013.803082. Epub 2013 Aug 19.
The biomechanics of the patellofemoral (PF) joint is complex in nature, and the aetiology of such manifestations of PF instability as patellofemoral pain syndrome (PFPS) is still unclear. At this point, the particular factors affecting PFPS have not yet been determined. This study has two objectives: (1) The first is to develop an alternative geometric method using a three-dimensional (3D) registration technique and linear mapping to investigate the PF joint contact stress using an indirect measure: the depth of virtual penetration (PD) of the patellar cartilage surface into the femoral cartilage surface. (2) The second is to develop 3D PF joint models using the finite element analysis (FEA) to quantify in vivo cartilage contact stress and to compare the peak contact stress location obtained from the FE models with the location of the maximum PD. Magnetic resonance images of healthy and PFPS subjects at knee flexion angles of 15°, 30° and 45° during isometric loading have been used to develop the geometric models. The results obtained from both approaches demonstrated that the subjects with PFPS show higher PD and contact stresses than the normal subjects. Maximum stress and PD increase with flexion angle, and occur on the lateral side in healthy and on the medial side in PFPS subjects. It has been concluded that the alternative geometric method is reliable in addition to being computationally efficient compared with FEA, and has the potential to assess the mechanics of PFPS with an accuracy similar to the FEA.
髌股（PF）关节的生物力学本质上很复杂，髌股不稳定的表现形式如髌股疼痛综合征（PFPS）的病因仍不明确。目前，影响PFPS的具体因素尚未确定。本研究有两个目标：（1）第一个目标是开发一种替代几何方法，使用三维（3D）配准技术和线性映射，通过间接测量——髌软骨表面进入股软骨表面的虚拟穿透深度（PD）来研究PF关节接触应力。（2）第二个目标是使用有限元分析（FEA）开发3D PF关节模型，以量化体内软骨接触应力，并将从有限元模型获得的峰值接触应力位置与最大PD的位置进行比较。已使用健康受试者和PFPS受试者在等长负荷下膝关节屈曲角度为15°、30°和45°时的磁共振图像来建立几何模型。两种方法获得的结果均表明，PFPS受试者的PD和接触应力高于正常受试者。最大应力和PD随屈曲角度增加，且在健康受试者中出现在外侧，在PFPS受试者中出现在内侧。得出的结论是，与有限元分析相比，替代几何方法除了计算效率高之外还可靠，并且有潜力以与有限元分析相似的精度评估PFPS的力学情况。
