Some days ago there was a question by Brent about ligaments in the spine
model. Here are my two cents about the ligaments.
When building the lumbar spine model the original idea was to include
ligaments as well. But at some point we decided not to include the
ligaments in the model, because of lack of readily available information
about the mechanical properties and slack lengths. We were in fear that
ligaments with wrong properties might give worse results than excluding
them.
However, during the building process we already defined nodes and
coordinates for four types of ligaments:
ALL = Anterior Longitudinal Ligament
PLL = Posterior Longitudinal Ligament
LS = Ligamentum Supraspinale
LI = Ligamentum Interspinalia
You can find these coordinates in for example the file:
\BRep\Aalborg\Spine\SegmentsLumbar.any
The definition of the ligaments are in the file:
\BRep\Aalborg\Spine\LigamentsSpineMiddle.any
Please note that the material properties in this file are pure fantasy
and that this file is not used in the present spine model.
So I guess my message is, that if one of you have good properties for
these ligaments it is actually very easy to include these four ligament
types in the lumbar spine model. Of course there are probably other
types of ligaments not defined yet, but this might be a start.
Regards, Mark
Mark de Zee, Ph.D., Post doc.
Aalborg University, Department of Health Science and Technology
Center for Sensory-Motor Interaction (SMI)
Fredrik Bajers Vej 7 D-3, 9220 Aalborg, Denmark
Phone: +45-96358818; Mobile: +45-29809367
E-mail: mdz@hst.aau.dk
Mark,
Thank you for the explanation. I may make use of the ligament nodes
in the future.
Brent
— In anyscript@yahoogroups.com, Mark de Zee <mdz@…> wrote:
>
> Dear Brent and others,
>
> Some days ago there was a question by Brent about ligaments in the
spine
> model. Here are my two cents about the ligaments.
>
> When building the lumbar spine model the original idea was to include
> ligaments as well. But at some point we decided not to include the
> ligaments in the model, because of lack of readily available
information
> about the mechanical properties and slack lengths. We were in fear that
> ligaments with wrong properties might give worse results than excluding
> them.
>
> However, during the building process we already defined nodes and
> coordinates for four types of ligaments:
> ALL = Anterior Longitudinal Ligament
> PLL = Posterior Longitudinal Ligament
> LS = Ligamentum Supraspinale
> LI = Ligamentum Interspinalia
>
> You can find these coordinates in for example the file:
> \BRep\Aalborg\Spine\SegmentsLumbar.any
>
> The definition of the ligaments are in the file:
> \BRep\Aalborg\Spine\LigamentsSpineMiddle.any
> Please note that the material properties in this file are pure fantasy
> and that this file is not used in the present spine model.
>
> So I guess my message is, that if one of you have good properties for
> these ligaments it is actually very easy to include these four ligament
> types in the lumbar spine model. Of course there are probably other
> types of ligaments not defined yet, but this might be a start.
>
> Regards, Mark
> –
>
> Mark de Zee, Ph.D., Post doc.
> Aalborg University, Department of Health Science and Technology
> Center for Sensory-Motor Interaction (SMI)
> Fredrik Bajers Vej 7 D-3, 9220 Aalborg, Denmark
> Phone: +45-96358818; Mobile: +45-29809367
> E-mail: mdz@…
>