Getting Real: The Deka ‘Luke’ Arm

It strikes me that I’ve been predominantly writing about my research into fiction lately without making much mention of the real world cybernetics I’ve looked into.

I used an image of Deka Research Corps ‘Luke Arm’ sometime ago on the blog but didn’t say anything about it, something I should remedy now as it’s a fascinating example of technology normally associated with sci-fi realised with surprisingly down-to-earth intentions. Despite having no offensive properties this advanced prosthesis was funded by Pentagon’s DARPA (Defence Advanced Research Projects Agency), a division typically associated with weapons and armour R & D. The 2005 initiative was started with wounded Iraq veterans in mind, specifically those who have lost arms though it seems fair to suggest the completed arm could have much broader benefits.

One of two simultaneously commissioned programmes, Deka’s project is not only over $10 million cheaper than its competitor – the John Hopkins Applied Physics Laboratory – but a great deal more feasible to boot. While the more expensive project has plans to develop a neurally controlled prosthetic arm with experimental technology, Michael Kamen’s New Hampshire medical company took the approach of making an advanced prosthesis available “for people who literally want to strap it on and go.”

Though considerably cruder than the alternative we’re still a long way off realising the kind of responsive cyborg replacements sci-fi typically envisions, while besides providing a more immediate solution for amputees the Deka arm is also implemented with less invasive measures. Ideas such as connecting to existing nerves would offer more naturalistic control, however it’s understandable that many would be put off by the surgery to say nothing of the additional costs and technical/biological complications.

As Kamen himself puts it ”Prosthetic legs are in the 21st century, with prosthetic arms we’re in the Flintstones.” I can certainly believe this last point having seen Paralympic runner Oscar Pistorius ‘The Blade Runner’ in action. Besides being reputedly uncomfortable and ill fitted, existing arm prostheses are clumsy, more complicated models being largely unmanageable while the basic ‘wire and hook’ is incapable of more delicate manipulations.

The Luke arm marks a leap forward in almost every area. Besides developing a new comfortable socket fitting, they ensured the arm to be lightweight and modular allowing adjustment for virtually any level of amputation. Formerly state of the art models only featured three powered joints and consequently only three degrees of freedom as opposed to the twenty-two offered by a living human arm, the Deka prosthesis doesn’t quite match this but comes remarkably close with eighteen.

Of course all these features would be meaningless without a comprehensive control system. As demonstrated by test subject Chuck Hildreth in the video below, manipulation is managed via a set of foot pedals – something I would have assumed to be fairly impractical, but appears quite precise in action – pushing down with different toes controlling rotations and contractions in the arm and hand, while the harness also detects muscle movements in his side toggling types of rotations and grips. Sensory feedback typical of a real arm remains an issue but this can also be addressed by a ‘tactor’, a device placed against the skin which vibrates with frequency proportional to pressure applied in a grip.

Perhaps this is beginning to sound like a high-tech sales pitch, but it has to be stressed the level of advancement this represents not just in the quality of living for amputees but for science in general. This is by no means a replacement for the human arm yet, but it’s remarkable what it can accomplish all the same. The Deka arm can do things its users would formerly have found impossible such as peeling a banana, operating a drill or holding a paper cup without crushing it.

In relation to my research what I find most interesting here is the optimistic image projected regarding such enhancements and cyborg technology. The cliché of the technological Apocalypse is a frequent concept in sci-fi cinema with the likes of Terminator and The Matrix envisioning our demise at the hands of our own creations, while the cyberpunk theme of ‘high technology, low humanity’ almost invariably sees them abused for selfish or destructive purposes. Looking at real world examples of these technologies provides a valuable counterbalance to the overzealous condemnation present in most fiction.

More bizarre to consider perhaps is not so much the influence of reality on fiction, but how fictional advancements could well be shaping real ones. I mentioned previously how the pioneering cyborg theorist Manfred Clynes claimed films like Terminator saddened him as they “misinterpret the message”. In the case of the Luke arm a different message appears to have been taken onboard: apparently the Deka complex has its own life size terminator figure, its missing arm replaced with a replica of their own one. Even the nickname ‘Luke arm’ itself is a homage to the cyborg hand Luke adopts to replace the severed one in Star Wars: The Empire Strikes Back. For all the detrimental impact sci-fi may have, its inspirational qualities shouldn’t be dismissed too easily either.

On a less optimistic note, marketing and distribution requirements need to be fulfilled before any specialised technology can really gain a foothold in everyday life. While the arm is said to have found funding for clinical trials (which it was still undergoing last time I checked) it also needs to be approved by the FDA (Food & Drug Administration) and secure commercial funding for distribution to the public. While the market is certainly there with 6000 in the US needing a prosthetic each year, it’s relatively small and consequently specialised. As a result it doesn’t present a particularly attractive opportunity for sponsors seeking financial gain, and even if they do fund it prices are likely to remain unaffordable for many due to the level of the sophistication and the cost to produce it.

What I can take from this example are effectively two things: that a formerly science fiction based technology may steadily be becoming a reality, but that without the required support it may never leave the test lab. In my own fictional setting I’m developing I should consider how this problem might be addressed in a cyborg-centric society.

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