Joint reaction analysis in OpenSim with results of CEINMS

[Ryo Ueno]

Hello,

I'd like to calculate anterior component of knee joint reaction force with results from CEINMS. Is it compatible with Joint Reaction Analysis in OpenSim?

Thank you,

Ryo

[Claudio Pizzolato]

Hi Ryo,

it is not directly compatible, but can be done with a bit of work. The main issue is that joint moment predictions from CEINMS do not equal the result from OpenSim ID. Consequently, the body dynamics is not balanced, which is a requirement for the Reaction Analysis tool. On the other hand, static optimisation in OpenSim uses reserve actuators to compensate the error between the joint moments calculated from muscle forces and from ID.

So, what you need to do is to use reserve actuators in OpenSim to fill in the error between CEINMS-predicted and ID joint moments and then calculate joint reaction.

Cheers
Claudio

[Ryo Ueno]

Thank you for your reply!

I understand that I need to add reserve actuators, but static optimization tool needs kinematics and GRF data. I can't use joint moments predicted by CEINMS, I guess. I've driven SO and joint reaction using GUI. Is there a way to add joint moments directly to drive SO or joint reaction analysis?

Joint reaction analysis also uses kinematics, GRF and muscle force data. So, can I use muscle force from CEINMS to calculate joint reaction force?

Ryo