joint force knee

Hey, I have a specific question concerning the 2D/3D bike model, maybe you could answer it…why is the insertion of the patella tendon (vasti, rectus femoris) ventral of the knee joint and not dorsal? That means that the sign of the x-force changes which is a large factor when calculating the total joint forces.

best regards, manuel

Hi Manuel,

The 2d leg model is simplified a lot.

I have create a picture of the 2d leg model it has a circle in the knee joint.

I am unsure what you mean by your question, please explain it in more detail using this picture.

Best regards

I add a graphic, one the left side you can see my opinion and on the right side you can the anybody 2d model. I mean the x-force of the patella (Fxpatella) has then 2 different signs (+ or -), depends which model is used.
Is my assumption wrong?
thanks for the support,

best regards,

Hi Manuel,

The Leg2D is not exactly as you say. I attached a picture explaining it. The patella is not present as a segment but it is modelled by a node on the tibia. The muscles insert directly on this node, and as the node is rigidly connected to the shank the force is trasmitted correctly.

Best regards, Sylvain.

in my case, i would like to model the lower extremity with a patella. So would you agree to my painted model (attachement, i.e. force transmission of the patella tendon shows to the right, you) or is this a false assumption?

kind regards,

Hi Manuel,

I think you should use the more advanced TLEM leg model (called LegTD in the repository) and not the simple 2D model. The LegTD is constructed exactly as you explain it in your picture, with the patella segment and the patella tendon.

Best regards, Sylvain.