Functional and Applied Biomechanics, Department of Rehabilitation Medicine, NIH, Bethesda, MD 20892-1604, USA.
J Biomech. 2012 Apr 5;45(6):1117-22. doi: 10.1016/j.jbiomech.2011.12.025. Epub 2012 Jan 28.
Patellofemoral osteoarthritis and its potential precursor patellofemoral pain syndrome (PFPS) are common, costly, and debilitating diseases. PFPS has been shown to be associated with altered patellofemoral joint mechanics; however, an actual variation in joint contact stresses has not been established due to challenges in accurately quantifying in vivo contact kinematics (area and location). This study developed and validated a method for tracking dynamic, in vivo cartilage contact kinematics by combining three magnetic resonance imaging (MRI) techniques, cine-phase contrast (CPC), multi-plane cine (MPC), and 3D high-resolution static imaging. CPC and MPC data were acquired from 12 healthy volunteers while they actively extended/flexed their knee within the MRI scanner. Since no gold standard exists for the quantification of in vivo dynamic cartilage contact kinematics, the accuracy of tracking a single point (patellar origin relative to the femur) represented the accuracy of tracking the kinematics of an entire surface. The accuracy was determined by the average absolute error between the PF kinematics derived through registration of MPC images to a static model and those derived through integration of the CPC velocity data. The accuracy ranged from 0.47 mm to 0.77 mm for the patella and femur and from 0.68 mm to 0.86 mm for the patellofemoral joint. For purely quantifying joint kinematics, CPC remains an analytically simpler and more accurate (accuracy <0.33 mm) technique. However, for application requiring the tracking of an entire surface, such as quantifying cartilage contact kinematics, this combined imaging approach produces accurate results with minimal operator intervention.
髌股关节骨关节炎及其潜在的前驱病变髌股疼痛综合征（PFPS）较为常见，且治疗费用高昂，对患者的生活质量有较大影响。PFPS 被认为与髌股关节力学改变有关；然而，由于难以准确量化体内关节接触运动学（面积和位置），尚未确定关节接触应力的实际变化。本研究开发并验证了一种通过结合三种磁共振成像（MRI）技术（电影相位对比（CPC）、多平面电影（MPC）和 3D 高分辨率静态成像）来跟踪动态、体内软骨接触运动学的方法。在 MRI 扫描仪中，12 名健康志愿者主动屈伸膝关节时，采集 CPC 和 MPC 数据。由于目前尚无用于量化体内动态软骨接触运动学的金标准，因此跟踪单个点（髌骨相对于股骨的起点）的准确性代表了跟踪整个表面运动学的准确性。准确性通过将 MPC 图像与静态模型配准以得出 PF 运动学，与通过 CPC 速度数据积分得出的运动学之间的平均绝对误差来确定。髌骨和股骨的准确性范围为 0.47 毫米至 0.77 毫米，髌股关节的准确性范围为 0.68 毫米至 0.86 毫米。对于纯粹的关节运动学定量，CPC 仍然是一种分析更简单、更准确（准确性 <0.33 毫米）的技术。然而，对于需要跟踪整个表面的应用，例如量化软骨接触运动学，这种组合成像方法可在最小的人工干预下产生准确的结果。
