Department of Mechanical Engineering, University of Melbourne, Parkville, VIC, 3010, Australia.
Ann Biomed Eng. 2023 Mar;51(3):493-505. doi: 10.1007/s10439-022-03048-2. Epub 2022 Sep 9.
Six kinematic parameters are needed to fully describe three-dimensional (3D) bone motion at a joint. At the knee, the relative movements of the femur and tibia are often represented by a 1-degree-of-freedom (1-DOF) model with a single flexion-extension axis or a 2-DOF model comprising a flexion-extension axis and an internal-external rotation axis. The primary aim of this study was to determine the accuracy with which 1-DOF and 2-DOF models predict the 3D movements of the femur, tibia and patella during daily activities. Each model was created by fitting polynomial functions to 3D tibiofemoral (TF) and patellofemoral (PF) kinematic data recorded from 10 healthy individuals performing 6 functional activities. Model cross-validation analyses showed that the 2-DOF model predicted 3D knee kinematics more accurately than the 1-DOF model. At the TF joint, mean root-mean-square (RMS) errors across all activities and all participants were 3.4°|mm (deg or mm) for the 1-DOF model and 2.4°|mm for the 2-DOF model. At the PF joint, mean RMS errors were 4.0°|mm and 3.9°|mm for the 1-DOF and 2-DOF models, respectively. These results indicate that a 2-DOF model with two rotations as inputs may be used with confidence to predict the full 3D motion of the knee-joint complex.
需要六个运动学参数来全面描述关节处的三维（3D）骨骼运动。在膝关节中，股骨和胫骨的相对运动通常用单自由度（1-DOF）模型表示，该模型具有单一的屈伸轴，或者用包含屈伸轴和内外旋转轴的双自由度（2-DOF）模型表示。本研究的主要目的是确定 1-DOF 和 2-DOF 模型在多大程度上可以准确预测日常活动中股骨、胫骨和髌骨的 3D 运动。通过对 10 名健康个体在执行 6 项功能活动时记录的 3D 胫股（TF）和髌股（PF）运动学数据拟合多项式函数，创建了这两种模型。模型交叉验证分析表明，2-DOF 模型比 1-DOF 模型更能准确地预测膝关节 3D 运动。在 TF 关节处，对于所有活动和所有参与者，1-DOF 模型的平均均方根（RMS）误差为 3.4°|mm（度或毫米），2-DOF 模型为 2.4°|mm。在 PF 关节处，1-DOF 和 2-DOF 模型的平均 RMS 误差分别为 4.0°|mm 和 3.9°|mm。这些结果表明，作为输入的双自由度模型具有两个旋转，因此可以有信心地用于预测膝关节复合体的完整 3D 运动。
