Sulcus_intertubercularis nodes AND EM and EL landmarks

Hi there,

I would like to know how the position of the sulcus_intertubercularis node was decided (proximal humerus). In the HumerusBoneGeometry file (AMMS 1.0 repository), there is one relative position that is active and another one that is commented, like as follow:


sRel=0.5*(.art_tub_majus.sRel+.art_tub_minus.sRel)+.Scale({…Sign*0.003,0.0,0.0});//midpoint

//sRel = .Scale({-0.007500, -0.004000, -0.035000}+.OffSet)*.Mirror;

If I draw the node with the set that is active (mid point), the point seems to be far from the bicipital groove. However, if I draw the node with the relative position that is commented, the point is much closer to the groove.

ALSO,

I would like to know why the EM and EL bony landmarks points are not at the right place on the distal humerus (higher than normal). I do I fix this ? Is this a problem with the Humerus_bone.anysurf (positioning or scaling) ? If not, can I just ajust the position manually ?

Thank you for the support

Pierre

Hi Pierre,

I think it just made sense to define sulcus_intertubercularis node as a mid point. You should not rely too much on the visual position on the bone cad file. You know the bone files and data for the points comes from a different source and it had been fitted together, so there can be some differences graphically.
Same for the EM and EL landmarks. Please feel free to modify them if you need to, you can just do it manually in the code.

Best regards, Sylvain.

Hi Sylvain,

I get your point. I was not sure if these points rely on the joints refnode definitions or on palpator datas. I’ll change the positions then.

Thank you.

I have another question about the longitudinal axis of the humerus. Do you know a good way to define this axis ? If, for exemple, I want to place a prosthesis with the bone, the definition of this axis will help me a lot.

For the moment, I work in a CAD software (CATIA) and I define all the relevant axes. Is there a mean to transfer them with the STL bone file or something else ?

Thank you.

Pierre.

Hi Pierre,

Right now the Y axis of the humerus is pretty well aligned with the longitudinal direction.

I don’t think you can import the axis from your Catia model directly with the stl file, but i suppose you can dump the orientation matrix of those axis. Then you can feed that into the ARel property of some nodes. But make sure that the base ref frame of the humerus used to calculate those matrixes is exactly the same.

An other solution is to use bony landmarks defining each axis, import those bony landmark positions into anybody and use them for the orientation of the nodes (using the RotMat function).

Best regards, Sylvain.

Hi Sylvain,

When I compare my longitudinal axis to the Y-Axis of the AnyBody ‘gh’ ref frame, I doesn’t give the exact same orientation, because I used another procedure to determine its orientation. Thus, two procedures gives necessarily two different orientations.

Thank you for your recommandations.

Pierre.