system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] What kind of prosthetic arm does Bucky have?

It's pretty clear he lost his entire arm yet his prosthetic makes him seem to be able to bend his arm and pretty much have complete control of  its movements as if he still had is actual arm in tact. Even before the Vibranium arm he could still shoot, fight, and even catch Cap's shield so how was all that possible on an amputee?
gpt
Science in the MCU advanced much faster than it did for us. We don't know the specifics of Bucky's original arm, but it was clearly an advanced, durable alloy connected to him through the nerve endings in his shoulder; when they remove the arm, it causes him extraordinary pain.

This kind of cybernetic-neurological link is a precursor to the mind-machine interfaces Stark developed for his Iron Man armors, at least indirectly.