3D Spine Kinematics on Riding Fitness Machines Using 2D/3D Image Registration

To achieve 3D kinematic analysis of total joint arthroplasty, 2D/3D image registration techniques have attracted attention in recent years. This study presents a 3D spine kinematic measurement method on riding fitness machines using a 2D/3D image registration. First, in order to create the 3D bone model of each spine, CT scan data from a healthy volunteer are used. Next, under fluoroscopic surveillance in the frontal and lateral planes, dynamic spine motions on riding fitness machines are recorded as serial digital x-ray images. 3D poses of each spine are estimated using a featurebased 2D/3D image registration which uses two directional fluoroscopic images and 3D surface model of spine, and finally the 3D kinematics are determined and visualized. In order to validate the accuracy of pose estimation for each spine using a feature-based 2D/3D image registration, computer simulation test was performed. The result showed that the root mean square errors were within 1.0 mm, 1.0 degree for all translations and rotations. In the clinical application 3D spine kinematic analysis using two type of riding fitness machines was successfully performed, and as the results the dynamic movement showed a smooth and reasonable physiologic pattern of motion.