A New Hope: Are Bionic Limbs Science Fact or Fiction?

A long time ago in a galaxy far, far away, prosthetic advancements were nothing to be sniffed at. The dawn of the 1980s brought the second film in the (soon-to-be) Star Wars franchise, The Empire Strikes Back, and with it, came one of the most famous examples of bionic prosthetics.

The climax of the film involves Luke Skywalker’s hand being forcibly removed and falling to seeming oblivion. Its replacement, a machine, is showcased in the closing scenes of the movie, with Luke seen lying in a medical setting as a droid pricks the fingers and palm of his new robotic hand, testing the reflexes and an access hatch revealing pistons and gears beneath synthetic skin.

The most fascinating aspect of the scene comes with the medical droid pricking Luke’s fingers, eliciting an immediate reflex response. The ability to mimic the human nervous system is incredibly complex and has long been the stuff of science fiction. Today, however, this reality is not too far-reaching.

To do this, scientists would have to be able to emulate the nervous capabilities of the hand and its ability to act as a sensory organ while also sending these signals being generated to the central nervous system (CNS), thus responding to the stimulus.

This is known as a bidirectional nature. A bidirectional information flow sends sensory and motor instruction to and fro, between limb and patient. Luke is seen to physically react to the pinpricks, both reflexing and exclaiming at the sharp pain.

The closest thing available today to this is the myoelectric prosthetic. These rely on the limb stump’s electrical activity to achieve their complex set of movements. This information is most commonly accessed from the activated muscles by means of electromyography (EMG). Non-invasive electrodes placed on the skin above the level of amputation measure potentials during contraction, which contains the neural instructions sent to elicit a certain movement. Current myoelectric upper-limb prosthetics offered are limited by the lack of sensory feedback to the user, unwieldiness, and a lack of suitable responsiveness. While many bionic limb users can dexterously manoeuvre their new limb, the next step is towards perceiving it as a part of the self.

Part of the challenge is reaching a point where one can accept the new prosthetic as their own, where it is no longer a tool, but part of their body. The integration of bionic limbs is not as simple as putting on your shoes or a new pair of sunglasses. Alongside the biological aspect that may be involved it takes time and an abundance of patience to work.

Through therapies and rehabilitation sessions, you’re essentially learning how to use your hand again. Taking into consideration this step of reconditioning is essential to making the experience fruitful. Like learning a new dance, practice makes perfect, and users must learn the distinct muscle contractions that make the hand do what they want.

Multiple advances in the field yield results that bring us closer to the level we see in science fiction. Targeted muscle reinnervations where severed nerves are surgically reattached to intact, spare muscles, mean any signals detected from these new muscles represent tasks the absent limb would normally carry out. This essentially rewires the remaining, non-intended muscles into carrying out nervous instructions intuitively and opens further possibilities for controlling prosthetics like multiple joints.

Prosthetics can also be osseointegrated, whereby prosthetics are attached directly to the bone, removing problems associated with a socket, like chafing, sweating and limited range of motion, and improving the experience stability-and-comfort-wise for the user.

Researchers classify success of prosthetics on their ability to allow the user to carry out Activities of Daily Living (ADLs) and therefore recapture autonomy in their lives that they may have lost. Regaining full function of all limbs can also go a long way to help regain degrees of sociality lost.

Surgeons and prosthetists are not only able to manufacture a hand, but transplant them too. Transplants are subject to intense scrutiny though, being marred with ethical and biological concerns and complications. Therefore, transplants aren’t seen as a viable solution for the problem.

Looking to the future, work on limb regeneration may take to the main stage. The phenotypically identical hand has the potential to render limb prosthetics redundant. The idea of growing a new limb could bypass problems with organ rejection, communication, and sensory feedback, having the additional benefit of being perfectly integrated.

The world’s first bionic arm was fitted in 1998. Robert Campbell Aird, the Scottish man fitted with the prosthetic, once famously proclaimed he was “part man, part machine, all Scottish”. Cost remains a major limitation in increasing the ubiquity and feasibility of prosthetics; something they don’t seem to worry about too much about in space. With increasing accessibility, quality, and options, it’s probably quite easy to argue that the reality of replacement hands is brighter than the fiction would have you believe.

Find Out More:

Is Luke Skywalker’s Hand Possible?

Literature Review on Needs of Upper Limb Prosthesis Users

Concerns about human hand transplantation in the 21st century

Hand Transplants, Daily Functioning, and the Human Capacity for Limb Regeneration

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