Estimation of the centre of rotation: a methodological contribution

The location of the centre of rotation of human joints that can be modelled as a spherical hinge can be estimated using kinematics information about the two adjacent bony segments involved recorded while the subject makes them move one relative to the other (functional method). In order to solve the relevant analytical problem, several algorithms have been proposed. Most recently, two methods, one based on a spherical best-fit approach and another based on the Reuleaux construction, have been presented as being different and submitted to comparative evaluation. This paper modifies the second method taking all information in the data set into account and shows that, having done this, the two methods coincide analytically.