PDA

View Full Version : motion of marker based shoulder joint center - reference data?



Rettig, Oliver
11-16-2006, 06:59 PM
Hallo,

I have done some work in application of least-squares methods for
shoulder joint center (SJC) estimation. The estimated SJC I have
expressed in coordinates of different technical coordinate systems
(TCS). I have tried some TCS fix to the humerus or fix to the
clavicle/shouldergirdle. Than I had a look at the motion of the SJC in
abduction and ante/retroversion. I have expressed the motion as
displacements to the SJC in a static normal position in ant/post and
medial/lateral direction. Depending on the TCS I have found
displacements in medial direction more than 7cm which does not agree to
my view. I think it is mostly caused by skin motion artefacts. Some TCS
fix to the humerus, work better that TCS of the clavicle. I can reduce
the displacements to less than 3cm. But I can not descide which of
different possible TCS is best for our application because I do not have
some reference of SJC movement for normal volunteers. I have seen
different characteristic motions depending on the TCS and I want to
analyse which of the characteristics is real motion and which are
artefacts.

It will be very helpful if somebody can send me some reference data or
references about SJC motion. I do not know if there are other non marker
based methods used to determane the motion of the SJC while abduction or
ante/retroversion. If so, this would be very intersting for me to
compare. But I am also interested in comparisons with the data of other



Best regards
Oliver Rettig

_________________________________________
Oliver Rettig
Dept. of Orthopaedic Surgery (Gaitlab)
Orthopaedic Clinic of Heidelberg
Schliebacher Landstr. 200A
69118, Heidelberg
Germany
Fax +49(0)6221-966725