Bucky's bionic arm is clearly an improvement on his human arm. From the page on Bucky's bionic arm from Marvel Cinematic Unvierse wiki;

The bionic arm gives him strength superior to that of Captain America. The Winter Soldier was able to rip open a S.H.I.E.L.D. armor SUV, rip apart Falcon's EXO-7 suit, and smash concrete by punching it. With his bionic arm supporting his already-enhanced natural strength, the Winter Soldier was able to overpower Captain America in a fight.

Why did they just not replace both of his arms with bionic arms, given that it's so much better than his actual arm?

  • 4
    My first guess would be that he does a lot of covert operations that require him to pass as a normal human, and having to keep both hands completely covered up all the time might be too impractical.
    – Ixrec
    Commented May 10, 2016 at 10:37
  • 2
    "The arm can function when not in contact with Barnes and can discharge bolts of electrical energy from its palm. The arm can discharge an EMP causing electronics to either shut down or become useless". Where did you get this information from? It certainly isn't given in any of the MCU films released so far. Commented May 10, 2016 at 10:53
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    @KyloRen That information is taken from the comics, which do not share a continuity with the films. As such, you either need to retag your question (as the question has nothing to do with the films) or remove the quote. Commented May 10, 2016 at 11:13
  • 5
    Obviously, he didn't want to lose more Essence. ^_^
    – FuzzyBoots
    Commented May 10, 2016 at 11:50
  • 1
    @T.J.L. Shadowrun, so that makes 2 of us at least ;)
    – Tim B
    Commented May 10, 2016 at 16:02

5 Answers 5


Because there are also downsides to his bionic arm.

And we see this in Captain America: The Winter Soldier. At one point, Black Widow throws a small device at The Winter Soldier's bionic arm, which seems to stick to it and completely disable it. He can't re-enable his bionic arm until he manages to take the device off with his human hand; he'd have been completely neutralised if both arms had have been bionic.

It would seem that Hydra/the Soviets/both/whoever actually gave him the bionic arm in the first place were aware of the fact that despite having advantages, it also has disadvantages, and as such they elected to only replace his missing arm, rather than replacing both.

It's also worth noting that in Captain America: Civil War;

We see that there were a further five Winter Soldiers created by Hydra/the Soviets/both/whoever at one point. It's worth noting that none of these Winter Soldiers had any limbs replaced.

That indicates that despite the advantages the bionic arm brings, it was decided that on the whole, a regular human arm is preferable if possible. That isn't possible in Bucky's case; hence, the bionic arm.


Better is a relative term. In the case of extensive, reconstructive surgery, even on a super-soldier, the idea was likely: Less is more. Given the requirements necessary to make the Winter Solider's arm the weapon that it is, it would require an extreme level of technological sophistication, even for Hydra and SHIELD-level technology.

The technology used to replace Barnes' arm has always been experimental and likely as advanced as anything able to be produced by Hydra. Even so, having a metallic arm meant Barnes was difficult to disguise and was relegated to the role of covert assassin and laboratory animal.

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  • Such an arm and the attendant technology is likely very invasive requiring a significant amount of physical trauma. Since Barnes had lost his arm already, replacement was deemed necessary, nothing more.

  • The technological component of connecting it to his nervous system, reinforcing his spine, creating the artificial muscles to actuate it (otherwise he loses a significant amount of physical strength) the coordination therapy and (re)training him to be able to use it each time it was upgraded would be expensive and time consuming.

  • Given Barnes' already extreme capability with the Winter Soldier program and ersatz Super-soldier serum, it was likely deemed unnecessary since the technology did come with other vulnerabilities and trade offs.


It seems to me that after his fall in Captain America 1, only his left arm needed amputating or it was already torn off. I don't remember which.

  • Hi, I understand that he only lost one arm which required the prosthesis, my argument is, that the prosthesis works better than his real one, so to make him an even more effective soldier, why not replace both arms? And just to let you know, this probably should have been a comment, I won't down vote you, but it might will get some down votes. Just for future reference.
    – KyloRen
    Commented May 11, 2016 at 4:38

the metal arm is strong but the normal arm can perform delicate tasks that require touch. grabbing small pieces of, say, a gun, performing surgery if he gets hit while on a mission, feeling heat or cold, etcetera. having only one metal arm is better than two metal arms or two normal arms.


It's powered by and manufactured of exotic materials which makes the arm very expensive, giving Bucky the arm was simply Hydra repairing a valuable asset.

If a main battle tank requires new tracks its cheaper than building a new tank, indeed you might want to upgrade the tracks while you're at it to prevent them breaking again. However this doesn't justify rebuilding the entire tank out of unobtainium, if you're going to do that you may as well scrap the original and build the super-tank from scratch rather than trying to build a super-tank on a regular tank chassis.

In other words if the robotic Bucky arm is better than the regular Bucky arm why not replace the entire body with a robotic Bucky? A Buckybot if you will.

Because it's wasteful. One super-tank or Buckybot may well be unstoppable but wars are fought on multiple fronts and battles are fought over strategic objectives. If one Buckybot costs as much as five unaugmented Buckys you're better off with the Buckys than the bot because (all else being equal) you'll win more battles that way.

If the enemy fields a Buckybot opposing it with a Buckybot of your own gives you a 50/50 chance of victory, whereas the five Buckys would likely defeat the single Buckybot easily if they ganged up on it because cost doesn't directly equate to effectiveness, there's diminishing returns. This factor of diminishing returns is why Hydra would give a wounded Bucky a robotic arm but wouldn't cut his arm off to equip him with one in the first place. Repairing a potentially valuable asset is justifiable as not repairing him would be a greater loss than the cost of upgrading him, whereas cutting the arm off in the first place is unjustifiable because that Bucky-arm has considerable value.

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