Lower body kinematics evaluation based on a multidirectional four-dimensional structured light measurement

We report on a structured light-scanning system, the OGX|4DSCANNER, capable of capturing the surface of a human body with 2 mm spatial resolution at a 60 Hz frame-rate. The performance of modeling the human lower body dynamics is evaluated by comparing the system with the current gold standard, i.e., the VICON system. The VICON system relies on the application of reflective markers on a person's body and tracking their positions in three-dimensional space using multiple cameras [optical motion capture (OMC)]. For the purpose of validation of the 4DSCANNER, a set of "virtual" markers was extracted from the measured surface. A set of musculoskeletal models was built for three subjects based on the trajectories of real and virtual markers. Next, the corresponding models were compared in terms of joint angles, joint moments, and activity of a number of major lower body muscles. Analyses showed a good overall agreement of the modeling outcome. We conclude that the 4DSCANNER within its limitations has the potential to be used in clinical gait analysis instead of optical marker-based systems. The advantage of the 4DSCANNER over OMC solutions is that it does not burden patients with time-consuming marker application. This study demonstrates the versatility of this measurement technique.