Validation of shoulder model in Flexion


when comparing my shoulder model with Bergmann’s/Rassmussen’s in abduction (with weight/nod weight) the results in force are almost the same. But when comparing the Van der Helm model (~1500 N, 90°) and my model (~1900 N, 90°) with Bergmann’s results (~780 N; 90°) the results are quite different.
I know that the simulated results are supposed to be higher, but twice as high seems akward.

What might be the reason?

Hi Haukee,

Let me clarify a few points. When you talk about Bergmann’s/Rassmussen’s you mean the following study, where abduction is 45 deg:

Rasmussen, J.,deZee,M.,Tørholm,S.,Damsgaard,M.,2007.Comparison of a
musculoskeleal shoulder model with in-vivo joint forces. Journal of Biomechanics 40(S2),S67.

Is that right?
Also what is your shoulder model based on?

Now, the GH reaction force seems to be quite subject dependent. I think Bergmann experiments have measured GH joint forces from about 300N to 800N for the same motion on different subjects. So you also have to consider that.

Best regards, Sylvain.