Knee Force & Moment

Main Forum
1

Hi everybody,

I would compare the results in terms of Force and Moment acting on the KNEE during level walking and the corresponding results obtained from Bergmann.
I am currently analyzing the MocapLowerBody present in AMMRV1.6.3.
This model releases two output:
>…BodyModel.SelectedOutput.Right.Leg.JointReacionForce
>…BodyModel.Right.Leg.MomentMeasure.KneeJointReactionMoment

Taking account of the coordinate system used by Bergmann, is correct to use the force and Moment present in “…BodyModel.SelectedOutput.Leg.JointReacionForce”?

(BERGMANN SAYS:“The coordinate system used is fixed relative to a right-sided implant. Its origin is located in the middle of the tibial plateau at
the height of the lowest part of the polyethylene insert. The positive force components Fx and Fy act in lateral and anterior
directions, respectively. The axial force component is reported as -Fz (with a negative sign) and always acts distally in the
direction of the implant shaft. Positive moments Mx, My, and Mz turn clockwise around their axes during flexion, abduction, and
outer rotation of the tibia, respectively. Positive values of Mx/My can be caused not only by frictional torque but also by a posterior/
lateral shift of the axial force -Fz.”)

P.S.:
I hope I have expressed myself clearly and I thank in advance anyone give me clarification.

2

Hi Jonathan,
sorry, but this is very complex in words. I think if you draw the refrence frame of the forces, you’ll understand it easier.

I think this should be it:

    Main.Studies.HumanModel.BodyModel.Right.Leg.Seg.Thigh.KneeJoint = {
    AnyDrawRefFrame DraFrame = {};
    };