THE IMPLEMENTATION OFADDITIONAL SOFTWARE FOR 3-DANALYSIS OF COUPLED MOTION INTHE CERVICAL SPINE BY MEANS OFAN ELECTROMAGNETIC TRACKINGDEVICE

摘要

New software was implemented to facilitate the control, the treatment and the organisation of the output stream of 3-D kinematic results, obtained with an electromagnetic tracking device (Flock of Birds) in a rehabilitation context. The creation of a number of user friendly menus provided easy file management in recording real time readings of discrete motion sequences. Software based adaptations of the reference frames allowed for the registration of relative data between the receivers, thereby starting from zero values, comparable to the neutral-zero method in clinical goniometry. With the implementation of a function "recalculate", a posteriori manipulation of the technical reference frames offered useful applications to avoid gimbal lock artefacts, to align the reference frames and to adopt them to the standardisation proposal of the International Society of Biomechanics (ISB). The software further provided simultaneous graphical display of the Euler angles in one window, and simultaneous graphical display of the translation components in another. The output data are saved in a format, which can be exported to current spreadsheets.The simultaneous graphical display of the axial rotation of the cervical spine and the associated components of lateral bending and/or flexion/extension in young and healthy volunteers, allowed good insight into the time characteristics of coupled motion. Most of the graphs showed the traditionally described ipsilateral coupled lateral bending. However, amplitude and shape of the curves revealed substantial inter-individual differences in amplitude and timing of coupled motion. Left-right differences, were obvious in many graphs. The presence of substantial functional variation in coupled motion of the cervical spine in young volunteers without complaints must warn us not to jump to conclusions.