Detection of incoherent joint state due to inaccurate bone motion estimation.

In biomechanical modelling and motion analysis, the use of personalised data such as bone geometry would provide more accurate and reliable results. However, there are still a limited number of tools used to measure the evolution of articular interactions. This paper proposes a coherence index to describe the articular status of contact surfaces during motion. The index relies on a robust estimation of the evolution of surfacic interactions between the joint surfaces. The index is first compared to distance maps on simulated motions. It is then used to compare two motion capture protocols (two different localisations of the markers for scapula tracking). The results show that the index detects progressive modifications in the joint and allows distinguishing the two protocols, in accordance with the literature. In the future, the index could, among other things, be used to compare/improve biomechanical models and motion analysis protocols.