Subtalar Joint Axis Definition?

[Paul McAlpine]

I am currently modifying the gait2354 model for my PhD research project. I am intersted in the axis definition of the subtalar joint...

Reviewing the .osim script I have calculated the inclination and deviation of this joint axis based on two sets of coordinates given in the talus body difinition --> the "orentation in parent" and "axis" points. As i understand these two points are given in the parent segment coordinate system and thus define the orentation of the joint axis. I am I correct in my thinking?

Based on this I have calculated a subtalar axis inclination of 38 deg and deviation of 9 deg. The inclination appears reasonable however the deviation appears a little low based on Piazza's 2005 review. Because I am not confident in my calculation method I am not sure how to proceed from here.

Any comments on this would be greatly appreciated.

[Peter Loan]

Hi Paul,

I checked the visual representation of the subtalar
axis in SIMM on the same model, and it does indeed
look like 38 deg inclination and 9 deviation. This
model has the same joint axis definitions as the
ones defined by Scott Delp for his dissertation
model, so you might want to check that for
references:
http://nmbl.stanford.edu/publications/p ... tation.pdf

Regards,
Peter