The arm really was impressive looking and if it even impressed Tony, then it must be something. He wondered if the arm was rather new then, he wasn't sure if HYDRA could put an arm like this on him. But... Zola had all kinds of crazy technology, so it wasn't out of the realm of possibility either.

Steve just knew that Bucky lost his arm during the fall. Or it was beyond repair by the time someone found him. Just another thing to blame himself about.

He started to look a little pained as Bucky confirmed his thoughts; that people operated on him and removed his arm because it was too damaged. Not only that, but Bucky was awake for said procedure... remembered what those scientists did to him. How painful it must've been to go through something like that.

"...HYDRA?" Steve managed to ask, his voice strained as he thought about what happened.