Model question: extended Rajagopal with ligaments

[Christopher Robin]

Hello - Beginner question here. I'm looking for a generic full-body model that includes soft tissues such as ligaments and joint capsules to more accurately model joint forces. I know that there are a few extended knee models that include, for example, ACL/MCL/PCL/LCL/CAP but I haven't seen a full body model that includes the soft tissues at the major joints including the shoulder, hip, elbow. What would be the best resource for this? Thanks!

[Nicos Haralabidis]

Hello Christopher,

I am not 100% sure there is a model out there that attempts to model each joint with the level of detail you are describing. Researchers typically increase the complexity based on the research question. So if you are interested in the small movements between the patella and the femur, for example, you will model that joint with greater detail and attempt to incorporate the passive structures surrounding the joint. An alternative approach is to lump the net effect of the passive structures into a moment-angle function based on experimental data - see here for an example for the lower extremity [1] - note that this approach neglects bone surface-to-bone surface contact (if you care about that take a look at the COMAK framework [2]).

Best wishes,

Nicos

[1] https://www.sciencedirect.com/science/a ... 8QCSqoOF-A

[2] https://link.springer.com/referencework ... 08-1_172-1

[Christopher Robin]

Thanks Nico, apologies for the delayed reply. That is helpful. Let's say we are interested in that level of detail of the passive structures of each of those 4 joints (knee, hip, shoulder, elbow). My guess is that there are research groups out there that have built a detailed model for each of those joints. Would it be possible to:

1. Find each of those specific models in the OpenSim database?
2. Add each of those detailed joint-level models to the most up-to-date full-body model currently being used?

My other thought was to use one of the automotive safety human body passive finite element models (THUMS or GHMBC) because I'm less interested in active motion control than stress/strain on connective tissues. My understanding (please correct me if I'm wrong) is that a passive model will be similarly accurate to an active model with respect to connective tissue forces but less accurate with joint contact forces?

Thanks!