The Fish-Tetrapod Transition, evolution of the "elbow" in Stem Tetrapods
The current research doesn't venture many details on the elbows/radius/ulna and locomotion biomechanics.
For the moment they just say the elbow was &quot;slightly flexible&quot; and that the bones were transitioning towards a round shape.
You can research deep into the resources and will perhaps find more.
Here are a resource which give context, found via &quot;locomotor performance in stem tetrapods&quot;
https://www.researchgate.net/publication/236460049_Historical_Perspectives_on_the_Evolution_of_Tetrapodomorph_Movement
There's also a 3D study of the legs here: https://www.researchgate.net/publication/227857349_Three-dimensional_limb_joint_mobility_in_the_early_tetrapod_Ichthyostega
https://sandykawano.weebly.com/locomotor-biomechanics-for-moving-onto-land.html