Is it possible for Wolverine style retractable bone claws, to work in real life? Either from the knuckles, or from the wrist (hidden blade style). How would such claws, if possible, change the appearance of the person?

If not Wolverine claws, then what other retractable claw designs are feasible in reality? What about shorter and thinner versions of Baraka's claws? https://upload.wikimedia.org/wikipedia/en/thumb/4/44/BarakaMK9render.png/220px-BarakaMK9render.png

Or a single claw extending from below the wrist? Doesn't have to be too long. Like the hidden blade from Assassin's Creed.

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    – Secespitus
    Apr 17, 2018 at 19:09
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    $\begingroup$ blades between your wrist and hand won't make you able to move your hand at all, your wrist would be literally blocked in place. Also wolverines blades are even longer than his forearms so when they are retracted he wouldn't be able to move his entire arm. $\endgroup$
    – Ekaen
    Apr 17, 2018 at 19:11
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    $\begingroup$ Ah, and every time the blades get out they would cut and slice bone and ligaments destroying your entire hand. $\endgroup$
    – Ekaen
    Apr 17, 2018 at 19:13
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    $\begingroup$ @Ekaen If you expand a bit you could easily make this into an answer, which allows people to more easily for example vote on whether that is a reasonable answer or not. You could also collect reputation for your answer, which you can't with comments. $\endgroup$
    – Secespitus
    Apr 17, 2018 at 19:15
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    $\begingroup$ @Ekaen Wolverine is one of my favorite characters, but that is something that has annoyed me for a long time. $\endgroup$
    – AndyD273
    Apr 17, 2018 at 20:29

6 Answers 6


For anything like a human hand (or vertebrate hand) only with super healing, Even in the most realistic iterations (aka ones where the claws sit entirely in the forearm when retracted and in between the metacarpals when extended) the path his claws take lies between the bones of the wrist, he is dislocating all the bones in his wrist every time. The movie illustrates this nicely, note two of the wrist bones even have an extra joint to allow the claws to pass through them. Your wrist would not work after that the tendons would be too damaged. Sliding them above the wrist might work but then there is nothing holding them in place, and they would be useless. If you tried to slash with them they would just rip out of your hands.

With an alien hand, constructed in a different way than earth vertebrates, and a single claw it would be possible. for strength reason they could not be very long. Although you have the issue of what is extending them, you need some weird muscle arrangements, but not impossible ones.


I would like to say first that I have no medical training and so, I'm far from an expert. However, I did look into the possibility of retractable claws in the past, and came to several conclusions. The answer, in my opinion, can be divided into two cases:

1. Retractable claws in a human hand structured as it is normally.

In this case, I don't believe such claws are possible. The human hand is a complex thing and there are tendons and nerves that run through the back of the hand that would have to be 'rewired' or moved for such an arrangement to work. The structure as it is cannot support anything more than there is.

2. Retractable claws in a human hand with alternative structure.

This case, I believe, holds more potential. Such 'claws' would have to be made out of or bone or better, keratin, with a likewise ability to be regrown if broken and be sharpened manually. They would not be as long as Wolverine's claws, as they can only be as long as the cavities holding them and the size of such cavities is highly restricted by the size of the part of the hand they sprout from.

There are three options for the placing of such claws:

1) Claws located in the fingers.

This is the location I initially researched, as my need was for feline-like claws.

Such claws would have to be short and probably curved, as there is not enough room within a finger, even a restructured one. I immediately ruled out the tip of the finger because it wasn’t what I was looking for. I wanted normal fingernails and hidden claws. This left the middle and proximal phalanges of the fingers. While the proximal phalanx of the fingers is longer and offers room of larger claws, I believe the middle one would offer more mobility, but essentially, the same would work for both.

I believe the structural changes necessary would be as such: middle phalanx proximal phalanx (pictures modified by me from one found here)

The phalanx bone would have to be split into two bones and the 'sheath' and mechanism would have to be fitted between them. (As in, muscles, tendons and the claw itself). The tendon running through the back of the finger would have to be rerouted, maybe split along the bones and mended at the next knuckle, so that when the hand is curled and the claws extend, the tendon would be held out of the way on both sides. Same for nerves.

the claw mechanism itself would have to resemble somewhat of a feline's claw mechanism so that they are unsheathed when the fingers are curled. Note that this would undoubtedly make the fingers thicker, and the corresponsive phalanges more fragile and more susceptive to compression pain.

2) Claws located along the metacarpal bones (the back of the hand).

In this approach, we can either employ the same method as with the finger claws, namely splitting the metacarpal bones and fitting the mechanism between the split bones, or fit the mechanism between the existing bones.

there is also the option of making the bones hollow and the spines be sheathed inside them. However, I am not sure how the sheath/unsheath mechanism would work in this case. Perhaps by combination of a ring of muscles at the exit of the sheath and a piston-like effect of a liquid or gas filled gland. This, however, would make the mechanism more complex than my level of anatomic knowledge can scope. It would also require lubrication within the ducts. It can be achieved by oil glands or some liquid like saliva.

In any case, these claws would need to be straight and would not be much longer than the finger claws.

3) Claws located along the forearm bones.

This, I feel, is the most plausible of the choices, since it requires less modifications. In this case, since there are already two bones in the forearm, the structural difference would have to be made between the bones to accommodate a long, narrow sheath in which one claw or spear like protrusion will be housed. It too will be made of keratin or bone, but I cannot envision more than a single such claw in each forearm. It can, of course, be as long as the forearm itself which would make it more viable as a weapon.

The unsheathing mechanism would have to consist of rings of muscles and tendons, a lubricating system and a fleshy sheath, since the normal claw sheath found in felines would not support such a claw. It is simply too long and would have to absorb or filter debris to some extent, as a means of hygiene. The forearms would look thicker, but not by much.

Such a claw would probably have a detachment mechanism since it can be torn or broken. The mechanism would guarantee there would not be lasting damage to the muscles and tendons of the retraction mechanism. The claw would then regrow, much like a horn or a nail.


In realistic terms, you cannot have any of those "retractable" claws because you'll be modifying so much of your bones and muscle so that it can withstand every strain you put into it.

Say for example Wolverine's claws. You need something that could really keep it in place, and as John already mention, if you try to slash something with it, you WILL rip your arms open. So bones need to be present for your claw.

Another thing is your claws composition. Imagine having a metal claw inside you, without having the strength to hold your claw. It might dig deep within your body if it's very sharp. PLUS, if it is sharp, imagine something ripping your hands every day if you are going to use it.

Bones are required to lessen your injury. This is if perhaps you don't have the healing properties of wolverine. What's more is that if you have to use it immediately, muscle alone cannot be controlled as to how far and how fast your claw would appear. It might be so fast your claw went flying or so slow that you're already dead before the claw even appears.

Bones are really needed to push and pull the claw, have it in place, protect your arms from being ripped open, and how fast the claw can appear, or sheathed.

Baraka's claws are another thing. That humongous claw is so unbelevable, you can defeat that guy if you just concentrate on hammering his claws - you can remove his arms if you are successful.

What I think is the most possible creature with a "Claw"-like structure based on what you describe would be someone that is a giant, does not have a retractable claw, but an extended bone that has a sharpened edge. Preferrably the bones of the knuckles are extended up until maybe a half foot far from the knuckle.

To support the claw, the Giant would have gloves so his hands won't be injured when picking up things, but his main problem I think would be if he was a male giant.

That said, I'll be saying that your claws sir, are realistically impossible. If you really want to have claws, make them cat-like claws instead.

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    – F1Krazy
    Apr 18, 2018 at 8:04
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    – Secespitus
    Apr 18, 2018 at 8:54

A single claw coming out of the wrist would have to fit in between the radius and ulna. I think that if you wanted something more realistic/easily explainable that doesn't limit mobility, then the wrist-claw option is good, since a single claw coming out just above the palm wouldn't be coming into contact with any of the bones in the hand, preserving movement there (but not in the wrist, since wrist flexion would be prevented with the claw out); if the claw is the right shape and size, then it could fit between the radius and ulna without inhibiting the twisting movement or noticibly changing the appearance of the forearm. The anterior side of the forearm (the side you see when you look at your palm) is mostly muscle and tendon anyways, so it's pretty easy to imagine a sheath that the claw could retract into without damaging or disturbing any of the real-life anatomical features the way Wolverine-style claws would. An opening for the claw to come through could, if the claw was shaped right, simply look like a small scar.


Yes. And unfortunately that would hurt like hell.

There could be two option on how it can happen. First is metacarpals splitting in two (or having just two pair of each, ind of like extra teeth) with the tendons still attached but the extra meta not connected to anything else. So every fist clench would move the tendons and extra bone structure forward.

Second solution is more "mutanty". You could have saliva outlet on your hand, with a stone in the duct. Muscle contraction could push part of the stone out creating a little spike. Here a video that show how it works in humans mouth.
Saliva stone poking out
Also some kind of degeneration that stores silica in hand and form tubelikes structures.


Yes. It is, in fact, possible. There would have to be an opening in the skin where the claws would protract, and it wouldn't be very large. It would protrude from the knuckles, and would behave like an animal's claws. You would lose the mobility of your fingers, however.


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