# Bending Moment

### From Orthoload Wiki

The resultant bending moment **M _{bend}**, acts in the middle of the femoral neck and perpendicular to the neck axis, and iscalculated with the following formula:

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The forces (F_{x}’, F_{y}’, F_{z}’) and moments (M_{x}’, M_{y}’, M_{z}’) are measured in the “implant coordinate system” x’, y’, z’ centered in the middle of the implant head. The force component F_{x}’ acts laterally, F_{y}’ acts anteriorly, and –F_{z}’ acts distally along the femur axis. The measured moment components M_{x}’, M_{y}’, and M_{z}’ turn right around the x’, y’, and z’ axes. N is the distance between the head center and the middle of the femoral neck and is equal to ½ L.
M_{tne} acts around the neck axis of the femur and represents the torsional loading of the neck. It is calculated by a -45° rotation of the "bone coordinate system” around the y-axis.

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