"The psychological challenges for amputees is daunting. More can be done, but in my mind, the key to success resides in enabling the amputee to seamlessly engage in activities of daily living," says David Hankin.

Hankin is CEO of the Alfred Mann Foundation - a medical research foundation based in California that works to create advanced medical technologies for people with debilitating medical conditions with the aim of improving their health and overall quality of life.

One area the foundation focuses on is limb loss - a condition that approximately 1.7 million Americans are living with.

According to the Amputee Coalition, around 185,000 amputations occur in the US every year - of which 97% are lower limb.

The main causes of limb loss are vascular disease - including diabetes and peripheral arterial disease - and trauma. A very small number of amputations are caused by cancer.

Physical and psychological difficulties

Individuals living with limb loss can experience difficulties physically and mentally.

Not only is limb loss a debilitating condition in itself, it can cause other conditions that impact a person's general health. For example, individuals with lower limb loss often have to use much more energy in order to be able to move around on different floor surfaces and terrain, and to travel distances that those with intact limbs would not find an issue.

"The additional energy and the wear and tear on other parts of the body create a host of medical problems for the amputee," says Hankin.

In a psychological sense, Hankin says that many amputees can experience feelings of inadequacy when it comes to engaging in day-to-day tasks. For example, something as simple as taking money out of a wallet may take much longer, which can cause embarrassment when the individual is standing in a grocery line.

When it comes to rehabilitation for amputees, prosthetic limbs are the first port of call. But Hankin says that rejection of artificial limbs - particularly upper limbs - is high. This is because most upper limb prosthetic devices do not have advanced functions that allow the amputee to effectively carry out daily activities.

"As a result, many end up in a closet or a drawer rather than affixed to the amputee," says Hankin, adding:

"There is a feeling among some amputees that not nearly enough has been or is being done to improve the technologies available to them and that there is no hope."

Prosthetic limbs: the road so far

It is believed the world's first prosthetic dates back to more than 3,000 years ago, after a fake toe made of leather and wood was discovered on an Egyptian mummy found near the ancient city of Thebes in 2000.

But of course, prosthetics have changed greatly since then - mainly in function rather than the way they look. In 1912, David Dorrance invented the body-powered arm. This was a device consisting of leather straps and a split hook. Using the power of their remaining arm, the wearer was able to open and close the hooks and pick up items.

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Prosthetic limbs have certainly advanced since the first wood and leather prosthetic toe more than 3,000 years ago.

Some scientists believe this creation paved the way for the future of prosthetic limbs.

"For upper limb amputees, powered, robotic hands and arms have been developed around the world to address the shortcomings of the body powered hook," says Hankin. "These hands and arms take the shape of human hands, looking somewhat like something from a science fiction movie."

When it comes to lower limb prosthetics, Hankin says technology has advanced even further:

"Powered feet, ankles and knees enable a lower limb amputee to achieve a more natural gait while absorbing much of the additional stress that would otherwise be absorbed by the amputee's trunk."

He adds that the kinetics of lower limb prosthetics have also improved, meaning lower limb amputees are able to tackle challenging surfaces and distances much easier.

But with such improvements in prosthetic limbs, why do some amputees continue to feel as if they have not advanced enough?

The future of prosthetic limbs

Think back 20 years ago. Most of us did not own a mobile phone, the internet was still on dial-up and a tablet was purely a form of medication. Needless to say, technology has certainly progressed in the last 2 decades. But has the world of artificial limbs been left behind?

"Humans have made great technological strides over the past 20 years, but only now are we seeing improvements in signal processing, materials sciences, electronics, etc. being applied to prosthetic limbs," says Hankin.

Although advancements in prosthetic limbs have been beneficial and allow amputees to better carry out daily activities, they do not provide the amputee with sensory information. Furthermore, the amputee is not able to control the prosthetic limb naturally with their minds.

These are the main areas of focus for artificial limb research, and it seems scientists are getting closer.

Medical News Today recently reported on the first amputee in the world who was able to "feel" in real-time with a sensory-enhanced artificial hand.

The prosthetic was created by Silvestro Micera and colleagues from the École polytechnique fédérale de Lausanne (EPFL) in Switzerland and the Sant'Anna School of Advanced Studies (SSSA) in Italy.

A video detailing the creation is below:

The prosthetic hand, containing sensors and electrodes, was wired to the upper arm of Dennis Aabo Sørensen from Denmark, who lost his left hand in a firework accident. Impulses that could be understood by the central nervous system were sent through the electrodes when Sørensen touched an item, allowing him to instantly feel it.

Last year, we reported on a study detailing the discovery of neural activity patterns that occur when animals manipulate objects, which researchers were able to recreate artificially - a process that could aid the creation of touch-sensitive prosthetic limbs.

The Alfred Mann Foundation have also created Implantable Myoelectric Sensors (IMES). These are implantable sensors that allow an amputee to control their artificial limb with their thoughts. The IMES system is currently undergoing clinical trials in the US and Europe.

"The use of systems like this with robust, capable robotic limbs that fit comfortably on the amputee will likely reduce rejection, increase function and enable the amputee to have a better quality of life," says Hankin.

Increasing investment may be key

It is clear that scientists are working hard to advance prosthetic technology. But like all improvements in technology, investment is key.

Hankin says public events involving amputees, such as the Paralympics, show people that individuals with limb loss have the ability to engage in day-to-day activities and can even exceed capabilities of individuals with intact limbs - something that helps increase investment into prosthetic technology.

He adds:

"We are starting to see frequent, mainstream media coverage of these kinds of events and the coverage is drawing an audience, attracting advertising support, etc.

I call this the mainstreaming of these kinds of events - the more that people with intact limbs learn and understand about the amputee community, the greater the acceptance which will lead to further investment into assistive technologies."

Hankin says that aside from better sensory technology and mind-control capabilities, more investment is needed to create better battery technology. "Robotic limbs require power - if we are able to deliver sufficient power in smaller and lighter packages, this will greatly benefit the amputee," he adds.

Furthermore, he says that the weight of prosthetic limbs is an important consideration. Therefore, investment into using lightweight materials for better and more functional prosthetics will be beneficial for amputees.

According to Hankin, such investments lead to one road: "Enabling the amputee to better engage in activities of daily living by providing better, more functional limbs and the systems to drive the limbs intuitively and naturally."

With more studies looking at how prosthetic limbs can be improved, maybe it will not be too long before touch-sensitive and thought-controlled prosthetics are available for amputees around the world.