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Comment by roarcher | Hacker News Reader

This is pretty amazing, but I wonder--how does the body adapt to having a piece of hardware that extends through the skin? Does the body not see this as an open wound? It seems like being permanently impaled with a metal pole.

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There are some metals that are well known to be biocompatible, as in no immune response. The video in the article has diagram of the inner screws into her arm. I'd guess the screws are Ti6Al4V, which is frequently used in knee replacements and other orthopedic surgeries.

It’s more or less the same idea as a dental implant, where the gum grows over it and closes it off to the exterior.

They do have a fairly high rate of both superficial and deep infection but advancements in coatings have improved the situation.

From what I remember, the major challenge was in the nerve-electrode connection, as they have a high failure rate and sending “sensation” signals back can easily cause nerve damage.

Not a doctor, but semipermanent ports are common. I imagine with the right coatings and materials, we know how to manage natural rejection.

Would probably assume some level of immunosuppressants might be necessary.

Like an earring? The skin typically forms a fistula-like sheath around the metal.

A fistula from a piercing connects two surface exits to each other, like a wormhole through your body. Once complete, the piercing touches nothing internal to you, just skin.

But in this case, the prosthetic must penetrate through the skin to connect to bone.

Then transdermals as popularized by Steve Haworth. They go through skin and are mounted to flesh and bone.

I'd have the same question about them. I'm not disputing that it works, I just don't understand how the body isn't constantly fighting it. Or leaking.

In the case of the Metal Mohawk, it actually was difficult for the owner to maintain. He kept bumping the spikes on things and eventually had them removed. Granted, his was a cosmetic change and not a functional one. I would be willing to put up with extra care to effectively replace a hand. Additionally, consider that people who receive donor transplants will use immune suppressants for the remainder of their life. That said, material selection is also important.

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