Can I intuitively wrap a ligament to prevent bone penetration?

[Ashleigh Louise Wiseman]

Hello!

Apologies for my probably naive question.

Background to the problem: I want to measure ligament lengths throughout a range of motion. I initially created 5 ligaments in the hip joint, but realised that I couldn't easily plot the length changes in the plotter tool, so I switched the ligament class to muscle class (FL, pennation angle etc is not a concern for the study, just the full length of the structure throughout the ROM; i.e., 1cm long at 45degrees FE versus 1.5cm long at 100 degrees FE is the sort of result I'm looking for).

When I implement the wrapping surfaces, the muscles 'jump off' the wrapping surface and pass through the bone at extreme DOFs (yes, these DOFs are probably non-biological, but they need to be included as part of the research question). No matter what I do with the via points/wrapping surfaces, I can't get a wrapping surface to work for the full ROM I am implementing.

So I was wondering if there was a way using the API to tell the muscles (or can revert back to ligament class if known how to easily extract length changes) that they can not penetrate through the bone obj at any time, and so intuitively wrap? I've never used the API before so as much help as you might be able to give would be very much appreciated! I'm using Opensim 4.3, but can revert back to 3.3 if needed.

Thanks! - Ashleigh