Validation of the interval deformation technique for compensating soft tissue artefact in human motion analysis

Abstract

Soft tissue artefact is the most invalidating source of error in human motion analysis. This error is caused by the erroneous assumption that markers on the skin surface are rigidly connected to the underlying bone. Several methods have been proposed in the literature to compensate for this spurious effect by mathematical modelling of the interposed soft tissues. Validation of these methods has been performed only on simulated data or on a small sample of data acquired from subjects mounting devices which limit skin motion. In the present study, the performance of one of the most recent compensation methods was evaluated using experimental data acquired combining stereophotogrammetry and 3D video-fluoroscopy. The effectiveness of the compensation method was found strongly dependent on the modelling form assumed for the motion of the markers in the bone frame. Even when the compensation produced a significant advantage in the evaluation of bone orientation, the estimation of position was critical. © Springer-Verlag Berlin Heidelberg 2003.