It is possible to compute the medial and lateral contact forces in the knee. You can read one of my publications on this topic (title: Simultaneous estimation of the path, magnitude and orientation of the femorotibial contact forces using bone geometry constraints: an exploratory numerical study for the stance phase of gait).
However, correct me if I am wrong Soren, but there is no model that actually does that in the repository. Creating such model is not a trivial task. I may still have the model somewhere in my folders, so if you are interested, I can try to provide it to you. However, it is an old version of Anybody and its repository. It would require major corrections to the actual code to make it work with the new version of the software and/or repository.
Thus, it might be more simple to reproduce the method in the paper using the latest version and repository. If you have smoe skills in Anyscript language (really close to C++), you may be able to do it.
For any question about the paper, you can contact me at : firstname.lastname@example.org