So I have a steampunk setting with some magic and I have a young, 20 year old female character who is supposed to have a full prosthetic arm. It might be assumed that the answer to this question could also be relevant for the integration of sci-fi prosthetics.
Such prosthetics are commonly attached to the body with osseo-integrated implants, which secures metal directly to bone, and the issue of skin adherence to an artificial surface has been solved with an artificial bone/antler/ivory like material. A certain degree of control and feedback is achieved through magical means, but it is not relevant to this question.
However it seems problematic to me that in this case, the entire upper arm bone is gone, and therefore also much of the ligaments and muscles that would normally attach the arm to the body. Also, potential hard points, like the collar bone and the scapula are mobile, so I'm not entirely sure how you might mount it. Would artificial ligaments be needed? Actual medical knowledge would be greatly appreciated.
How would you mount the prosthetic permanently to the body in a load bearing way?
To be clear, I am looking for a permanently attached and bio-integrated prosthetic as opposed to a traditional harness.
(Edit - I was hesitant to use flexible materials in the implanted parts because I wanted the parts directly fused with the body to be extremely long lasting and hard wearing. I was worried that given most materials' lack of self healing ability, that you would want most parts of the prosthetic outside the body, where parts can be easily replaced.)