Lumbar Spine Axial and Lateral moment measurement

[victorwambugu]

Hiello,
I would like to measure lateral and axial moments at the T12L1, L1L2, L2L3, L4L5, L5S1 joints.
The Selected output file is missing these outputs.
How can I measure these values for the standing human model?

Thanks!

Victor

[mkjung9980]

Dear Victor,

Sorry for late reply.

Our lumbar spinal joints are modeled as a spherical (ball) joint so that there are 3 reactional forces only.

So the lateral and axial moments that you are looking for should be calculated by considering the effects from relevant muscle forces.

Then the easiest way for that calculation is to use the AnyForceMomentMeasure2 class with respect to a specific lumbar spine joint considering all relevant muscle and joint forces.

The reason whey we have not prepared for those spinal lateral and axial moments is that it is actually not that easy to consider all those elements without any mistake.
What I mean is that it is possible technically, but simply we have not prepared it yet.

You can try to develop your own measurements. And following is a nice example for the implementation of the knee moments by muscles:

AnyForceMomentMeasure2 KneeNetMomentMuscle = 
{
  AnyRefFrame &ref = ..Seg.Thigh.KneeJoint.RotNode;
  //RefPoint = &..Seg.Thigh.KneeJoint.RotNode; 
  IncludeSegments = 
  {
    &..Seg.Shank, &..Seg.Foot, &..Seg.Talus    
  };   
  AnyObjectPtrArray pArrJntReactions = {
    &..Jnt.PatellaMovement.Reaction
  };  
  IncludeForces = arrcat(
    ObjSearch("..Mus.*", "AnyMuscle"), 
    ObjSearch("..TrunkMuscles.PsoasMajor.*", "AnyMuscle"),
    ObjSearchRecursive("..JointMuscles", "*", "AnyMuscle"),
    pArrJntReactions
  );
  
  AnyVec3 Mlocal=M*ref.Axes;
  AnyVar MKneeFlexion=Mlocal[2];
};

I’m sorry if this answer does not help you directly.

Best regards,
Moonki

[victorwambugu]

Hi Moonki,

Thank you for your answer. It will help me make a good attempt at estimating the spinal joint moments.

Best,
Victor.