Hi @faa198501
We do not have any forward dynamic solvers in the AMS so the closest thing you can get is by using our Force Dependent Kinematic (FDK) solver.
For facets joints and FDK we actually have a model in the AMMR repository that i think you should look at. We call it SpineFixationWithForceDependentKinematics and you can find it in your ammr here: ammr\Application\Examples\SpineFixationWithForceDepKinematics
Best regards,
Bjørn
AnyBody Technology
Thank you for letting me of this. But is it possible to calculate the motion and the motion values of L3,L4,L5 during flexion and how can I do this?
Best regards
You can see the joint angles by finding the Pos property of each joint. Example:
Main.HumanModel.BodyModel.Trunk.JointsLumbar.L4L5Jnt.Pos is the L4L5 xyz joint angles in radians.
Best regards,
Bjørn
AnyBody Technology
Thank you for your kind response. I would like to ask when we specify the bending (flexion angle) is the position and orientation of vertebrae in this time is calculated as part of analysis or is specified as input to the analysis? I need to understand how the software works so i can use it in a better way,
Thank you very much
Hi @faa198501
You are free to ask all the questions you like.
We love users who wants to understand our software!
It is actually a very good question you have.
In the AMS we have implemented rhythms to control the lumbar spine model.
So when you drive the flexion angle the rhythm takes care of driving the individual vertebras.
So their position and orientation is input to the analysis.
You can read more about the lumbar spine here and on the page you can find links to more information about the rhythm.
Best regards,
Bjørn
AnyBody Technology
I really appreciate your kind responses. I cannot find the joint moments for L4-L5 and L3-4 as you can see in the attached pictures. I only found other vertebrae not the lumbar. Also, I found the reaction forces for L4-L5 and L3-L4 but not their moments. Please kindly help
Also in addition to the previous question, can you kindly let me know if the shear forces are the mediolaterel and anteroposterior reaction forces? if not, how can I get the shear forces?
thank you very much
Hi @faa198501
The lumbar joints are made using the AnySphericalJoint can thus do not have any moments. The best thing you have are the reaction forces for those joints.
You are correct regarding the shear forces.
Best regards,
Bjørn
AnyBody Technology
Thank you very much. I am trying to add flexion to the “standinglift” model in the examples folder and increase the flexion angle in the “WilkePressureStandingFlexed” from validation folder. Please kindly let me know the steps to achieve this in both models.
Thanks again
Hi @faa198501
You must change the drivers that impose the movement on the model.
Look in the JointsAndDrivers.any files of the models and add/change the drivers for the degrees of freedom you are interested in.
Best regards,
Bjørn
AnyBody Technology
Does the Wilke spine model in the validation folder have moments to be measure similar like to reaction forces? Is there any model that has the lumbar vertebrae as non-spherical joints so I can measure the moments?
Thank you
Hi @faa198501
The Wilke Spine Model also utilizes spherical joints for the lumbar joints.
As mentioned above we have two models with facet joints in the lumbar region.
FacetJointModelSpineFixationWithForceDepKinematicsOtherwise you can implement different joint types yourself.
Best regards,
Bjørn
AnyBody Technology
Thank you very much. Can you please let me know how to get the forces by multifidus muscle only from the total reaction forces in the axial direction and other directions. Because I think that the axial forces that I get during flexion are for everything (other muscles and weight) including multifidus, but I need only the forces by multifidus.
Best regards
Hi @faa198501
You can do that by using the AnyForceMomentMeasure2 class.
Here is a link to get a example of how to use that class.
I would suggest to start of by making a ultra simple model of one segment and one muscle and try the class on that - it is easy to make mistakes using the class so a little practice helps a lot.
Best regards,
Bjørn
AnyBody Technology
I really appreciate your kind support. I would like to ask about how to eliminate the spherical joints and use instead disc Stiffness and ligaments for calculations in Wilke model and other models?
When I change the values (such as coef in DiscStiffnessRupture and IVD stiffness) nothing changes in the outputs...what values does the disc stiffness affect/or affected by?
do you have a tutorial about using disc stiffness of the spine?
Thanks a lot
Hi...I wish you a pleasant day,
I am using the spine fixation with force dependent kinematics but how can I change the force of multifidus and disc stiffness to get new positions? I am not quite sure if changing the PCSA will increase the force or is it the F0? if it's the F0 I couldn't find a value to change, please help me to modify it.
thank you very much
Hi @faa198501
You are on to the right things here.
To alter the Multifidi muscle strengths you can alter their PCSA since that is part of calculating the maximum strength F0. there is also a high level handle to control the strength on all spine muscles - Main.HumanModel.StrengthParameters.SpecificMuscleTensionSpine that controls the muscle tension N/mm^2.
To change the disc stiffness there are less direct options.
There is a BM statement where you can set the type of disc spring to either none, linear or non-linear called BM_TRUNK_DISC_STIFNESS
if that do not suit your need, you will have to manually go in and change the function controlling the disc stiffness. You can find it in the ../ammr\Body\AAUHuman\Trunk\DiscStiffness.any file.
Best regards,
Bjørn
AnyBody Technology
Thank you very much for your kind and continuous help. I really appreciate your efforts to support your users. Please keep the good support.
Thanks again
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