Biomedical Engineering Reference
In-Depth Information
floating axis
and finally internal/external rotation about
axis
attached to the humerus [WU 05].
Figure 3.8.
JCS of the glenohumeral joint recommended
by the ISB, modified according to [WU 05]
However, this sequence of rotations can, on the one hand,
result in “gimbal-lock” (when axes
are closely
aligned) and on the other hand, the angles obtained are
difficult to interpret from a clinical point of view for some
shoulder movements. Other different sequences have been
tested on several analytical movements [ŠEN 06], without
reaching a suitable solution for all these movements. Other
authors have proposed to align the axes of the distal SCS
with those of the proximal segment in an initial reference
position, and showed that this improved interpretation of
results and reduced the inter-subject variability for elevation
in the scapula plane [HAG 11, LEV 07]. For complex
movements, such as tennis serves, the sequence X-Z-Y was
found to be the most efficient [BON 10]. Therefore, for this
joint, it appears that the rotation sequence must be adapted
according to the type of shoulder movement analyzed. In this
case, the choices made must be specified so that the results
obtained can be widely used.
and
