knee modelin in opensim

[Martin Mössner]

Hi there, we are trying to calculate the ACL loads. For this we have chosen following approach:

1) Chose a OpenSim model with approriate knee modeling
2) Chose a posture, e.g a standing position with knee flexed to some extent
3) Chose a loading: e.g. a normal force compensating the weight and (!) some internal or external moment onto the tibia
4) Do a static optimization with opensim to get the muscle forces
5) Do a jointreaction analysis to get the contact force of the femur onto the tibia in the tibia coordinate system.
6) Use the paper of Weinhandl et al. (2016) to calculate the acl force

We started with the model gait2392
This model does not include the patello-femoral force and so the force in the knee is the sum of the force of the
femur onto the tibia plus the force of the patella onto the femur

Because of this we switched to the model of Rajagopal
Now the force of the femur onto the tibia is ok, but the model has only one degree of freedom in the knee

This is why we added rotational freedoms for internal/external rotation and ab-/adductuin into the knee by
editing the osim file

Finally we observed, that for large knee angles, the model of Rajagopal is not valid, but,
the improvement presented by Catelli et al. (2019) works fine.

The above models have the drawback, that no knee ligaments are considered.
Now we found two models including knee ligaments.
The one of Xu et al. (2015) and the one of Stanev et al. (2016)
Here are my questions:

1) Does there exist versions for OpenSim 4.0 of these models?
2) If not, can I install OpenSim 3.3 without interfering?
3) These models rely on some plugins for the ligaments. How do I install them? Are there examples of usage?
Are there interfaces to acess the acl load?

4) How do these models relate to the obove mentioned models.

Hopefully someone can give me some answers, thx
Martin