Rajagopal's model bone geometry

[Axel Koussou]

Hi all,

I'm using the Rajagopal's model to compute muscle-tendon unit lengths during passive joint sollicitation on children with cerebral palsy.

In this population, bone deformities can be important. Thus, I would like to personalize the model geometry to the subject. Specifically, I would like to take into acccount of the femoral anteversion and tibial torsion and modify the GemoetryPath of the muscles in consequence (and also, the wrapping surfaces ? Do you think that it is necessary to also modify this surfaces?).

To do so, I have to know what is the basic femoral anteversion and tibial torsion of the model. But I can't find these informations in the paper.
Do you know the answer or do you know a way to obtain these informations?

Thank in advance,

Regards

[Axel Koussou]

Hi all,

Sorry to ask this again but does anybody have these informations?

Thanks in advance,

Regards

[Mohammadreza Rezaie]

Hi Axel,

This project might be of your interest:
https://simtk.org/projects/bone_deformity/

Best,
Mohammadreza

[Axel Koussou]

Hi Mohammadreza,

Thank you for your answer.

I will definitely look at this project !

Regards

[Ayman Habib]

Hi Axel,

Questions regarding the model origins/assumptions are best answered by the model authors. If you can reach out to her directly that would be best.
Regarding bones, keep in mind that bone meshes are used exclusively for visualization, so you could change muscle paths, move joint attachment frames and wrap objects etc. studying all the effects you want to study without making custom mesh files. You could for example create a new "Frame" on a body, make the path points of the muscle(s) of interest refer to it, then move the frame around to effect a deformity, it's up to you, the model creator.

Hope this helps,
-Ayman

[Axel Koussou]

Hi Ayman,

Thanks for your great idea.

Nevertheless, would it be possible that you tell me how to a create a new Frame on a body. I can't find this information.
Moreover, this solution would also be possible for wrap objects? I ask this question because I can't find where it's indicated (in GUI or in the osim file) what frame these objects refer to.
In attachments, you can find two images of the GUI interface of the GeometryPath properties of the Addbrev muscle
showing that frame is defined for attachments points but not for wrap objects.

Thanks in advance,

Regards

[Sina Tabeiy]

Hi Alex,

Did you find the answer of your very last question about body frame and wrapping surfaces? If so, would you please kindly share it with me?

Sincerely,

Sina

[Axel Koussou]

Hi Sina,

I am sorry but I did not find any answer to this question.

Finally, I used the project shared by Mohammadreza, to which I added a function to rotate the wrapping surfaces. I can share this function with you, if you wish.

If so, I let you contact me.

Thanks in advance,

Regards

[Najoua Assila]

Hi,

The wrapping objects are created under their frame.
In the GUI, you can find the information in the model tree in the navigator. Under each body, you can see the wrapping objects (INFSPcyl) fixed to its frame (scapula).

Tree_wrap.PNG (7.03 KiB) Viewed 1202 times

In the osim, it is the same logic, under each body of the body set, you will find the wrapping objects nested under WrapObjectSet.

Hope it helps,

Najoua