[Analysis of human tibio-femoral joint relative kinematics based on 3D image registration]

This study sought to quantify normal human tibio-femoral joint kinematics in vivo. An eligible volunteer (a man in good health) was recruited, and a technical method of 3D image registration and coordinate transformation was used. The 3D point cloud models of his knee-flexion were illustrated by computed tomography. By use of the technique for 3D image registration, different models of several positions of knee-flexion were aligned to the same coordinate system. As for each model of the knee, the object coordinates of femur and tibia were built on the same location and direction in comparison with individual femur and tibia. Consequently, the error of constructing the object coordinate system in various coordinate systems can be avoided. Meanwhile, improved orthogonal coordinates systems were built on femur, tibia and patella. After orthogonal coordinates were built on each part of the knee, the Euler angle coordinate transformation was applied to acquire the data of the knee relative kinematics. Additionally, the data was proved to be effective, compared with that of recent literatures. With this method, arbitrary reference coordinates, or any alternative reference mode could be used in reconstruction of knee 3D kinematics images on a computer, and be applied in the kinematical analysis of other human joints or bones.