Question about knee joint

Archive AnyScript Yahoo archive
21

Hi Guys,

Peter, your attachments did not go through. I think Yahoo strips them
off by default.

It is actually possible to include the joint reactions in the muscle
recruitment problems, and we are using this heavily in the model of the
gleno-humeral joint. This enables us to ensure that muscle recruitments
will not dislocate the shoulder.

The trick is to explicitly set relevant components of Reaction.Type
inside the joint to Off (they are on by default) This will mean that the
joint no longer offers kinetic support in the directions in question.
This support is then replaced by adding AnyGeneralMuscles’s to the same
components of the kinematic measures inside the joint. Don’t forget, if
you attempt this, that the muscles are unilateral, so if you want
support in both positive and negative direction you need two muscles.
Now set the strength of the muscle model to whatever force you think the
joint can support. This will cause the muscles to be activates such that
the joint reaction limit is not exceeded.

Best regards,

John

John Rasmussen,
Professor, PhD, The AnyBody Group, Dept. of Mech. Eng.
Aalborg University
www.ime.aau.dk/~jr, jr@ime.aau.dk <mailto:jr@ime.aau.dk>
Mobile: +45 2089 8350. Phone: +45 9940 9307 (New number!)

From: anyscript@yahoogroups.com [mailto:anyscript@yahoogroups.com] On
Behalf Of Peter Worsley
Sent: 12. september 2008 12:17
To: anyscript@yahoogroups.com
Subject: Re: [AnyScript] Re: Question about knee joint

Dear all,

glad to spark some conversation on this topic. Thank you everyone for
your
input and the papers regarding co-contractions. I agree with john that
the
models heavily depend on the input quality and solver penalties, but I
feel
there is a evident need for co-contractions. Certain joints (knee for
example)
are heavily constrained in the anatomical sense by muscle input and
co-contractions during mid-flexion high loading activities. I’ve
attached a
small summary with some literature on the subject.

Perhaps an option for the recruitment solver would be to include a
function to minimise joint constraint reaction (similar human
musculoskeletal
system) so the joints are in better equilibrium during dynamic movement.
Perhaps the computational expense would be warranted by more accurate
outputs
from the model.

best wishes

Peter

[Non-text portions of this message have been removed]

22

Hi Guys,

thanks for the recommendations John, I’ll have a go at inputting them into the
model.

Here is a list of some of the references that were included in the failed upload
summary;

1.           Kingma,
I., S. Aalbersberg, and J.H. van Dieen, Are
hamstrings activated to counteract shear forces during isometric knee extension
efforts in healthy subjects? Journal of Electromyography and Kinesiology,
2004. 14(3): p. 307-315.

2.           da Fonseca, S.T., et al., Muscular co-contraction
during walking and
landing from a jump: Comparison between genders and influence of activity
level. Journal of Electromyography and Kinesiology, 2006. 16(3): p. 273-280.

3.           Aagaard, P., et al., Antagonist muscle coactivation
during
isokinetic knee extension. 2000. p. 58-67.

4.           Aalbersberg, S., et al., Co-contraction during static
and dynamic
knee extensions in ACL deficient subjects. Journal of Electromyography and
Kinesiology, 2005. 15(4): p.
349-357.

best wishes

Peter

— On Fri, 12/9/08, John Rasmussen <jr@ime.aau.dk> wrote:
From: John Rasmussen <jr@ime.aau.dk>
Subject: RE: [AnyScript] Re: Question about knee joint
To: anyscript@yahoogroups.com
Date: Friday, 12 September, 2008, 11:42 AM

Hi Guys,

Peter, your attachments did not go through. I think Yahoo strips them
off by default.

It is actually possible to include the joint reactions in the muscle
recruitment problems, and we are using this heavily in the model of the
gleno-humeral joint. This enables us to ensure that muscle recruitments
will not dislocate the shoulder.

The trick is to explicitly set relevant components of Reaction.Type
inside the joint to Off (they are on by default) This will mean that the
joint no longer offers kinetic support in the directions in question.
This support is then replaced by adding AnyGeneralMuscles’s to the same
components of the kinematic measures inside the joint. Don’t forget, if
you attempt this, that the muscles are unilateral, so if you want
support in both positive and negative direction you need two muscles.
Now set the strength of the muscle model to whatever force you think the
joint can support. This will cause the muscles to be activates such that
the joint reaction limit is not exceeded.

Best regards,

John

John Rasmussen,
Professor, PhD, The AnyBody Group, Dept. of Mech. Eng.
Aalborg University
www.ime.aau.dk/~jr, jr@ime.aau.dk <mailto:jr@ime.aau.dk>
Mobile: +45 2089 8350. Phone: +45 9940 9307 (New number!)

From: anyscript@yahoogroups.com [mailto:anyscript@yahoogroups.com] On
Behalf Of Peter Worsley
Sent: 12. september 2008 12:17
To: anyscript@yahoogroups.com
Subject: Re: [AnyScript] Re: Question about knee joint

Dear all,

glad to spark some conversation on this topic. Thank you everyone for
your
input and the papers regarding co-contractions. I agree with john that
the
models heavily depend on the input quality and solver penalties, but I
feel
there is a evident need for co-contractions. Certain joints (knee for
example)
are heavily constrained in the anatomical sense by muscle input and
co-contractions during mid-flexion high loading activities. I’ve
attached a
small summary with some literature on the subject.

Perhaps an option for the recruitment solver would be to include a
function to minimise joint constraint reaction (similar human
musculoskeletal
system) so the joints are in better equilibrium during dynamic movement.
Perhaps the computational expense would be warranted by more accurate
outputs
from the model.

best wishes

Peter

[Non-text portions of this message have been removed]

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