Using MR Imaging and X-Ray Fluoroscopy to Quantify the Effects of Soft-Tissue Artifact on Measurement of Knee-Joint Kinematics

The ability to accurately measure joint kinematics in vivo is of critical importance to researchers in the field of biomechanics [1]. Applications range from the quantitative evaluation of different surgical techniques, treatment methods and/or implant designs, to the development of computer-based models capable of simulating normal and pathological musculoskeletal conditions [1,2]. Currently, non-invasive marker-based three dimensional (3D) motion analysis is the most commonly used method for quantitative assessment of normal and pathological locomotion. The accuracy of this technique is influenced by movement of the soft tissues relative to the underlying bones, which causes inaccuracies in the determination of segmental anatomical coordinate systems and tracking of segmental motion. The purpose of this study was to quantify the errors in the measurement of knee-joint kinematics due solely to soft-tissue artifact (STA) in healthy subjects. To facilitate valid inter-subject comparisons of the kinematic data, relevant anatomical coordinate systems were defined using 3D bone models generated from magnetic resonance imaging (MRI).