A pioneering surgery technique known as bionic reconstruction, which enables the control of a prosthetic hand with the mind, has been performed for the first time.
The surgery was performed on three Austrian men with injuries to a group of nerves in their neck known as the brachial plexus, which is responsible for sense and movement in the shoulders arms and hands. The injuries – a result of vehicle and climbing accidents – had resulted in the three men having very little use of one of their hands.
The bionic reconstruction surgery involved amputating the functionless hand and replacing it with a prosthetic, which was connected to each patient’s remaining arm muscle and nerves, allowing them to control it through thought.
“The scientific advance here was that we were able to create and extract new neural signals via nerve transfers amplified by muscle transplantation,” explained Professor Oskar Aszmann, director of the Christian Doppler Laboratory for Restoration of Extremity Function at the Medical University of Vienna, and co-developer of bionic reconstruction.
“These signals were then decoded and translated into solid mechatronic hand function.”
Although clearly a major part, the actual surgery was only one aspect of the bionic reconstruction process, as all three patients prepared for an average of nine months prior to their surgery.
To start with, the patients underwent cognitive training to reactivate the under-used muscles in their arm, before learning to control a virtual hand that responded to electrical signals from their muscles.
After this, they learnt to use a hybrid prosthetic hand, which was connected to their non-functioning hand using a special device similar to a splint. This allowed them to practice controlling a prosthesis before undergoing amputation.
Once they were comfortable with the hybrid, the patients underwent the surgery. This involved transfer of a selection of nerves and muscles, the amputation of the non-functioning hand and the connection of the prosthesis, which contains an array of sensors that detect and respond the the muscles’ electrical signals.
After three months recovery, all three patients were able to perform a wide range of tasks with the new hand, such as using a knife to cut meat, pouring water out of a jug and using a key.
While a radical step, the bionic reconstruction surgery has given the men far greater freedom to perform tasks, allowed them a greater quality of life and has reduced their pain.
With few other effective medical treatments available, without the new surgery they would have likely been faced with a lifetime of pain and limited hand use.
“In effect, brachial plexus avulsion injuries represent an inner amputation, irreversibly separating the hand from neural control,” said Aszmann.
“Existing surgical techniques for such injuries are crude and ineffective and result in poor hand function.”
The research, which was undertaken along with engineers from the Department of Neurorehabilitation Engineering at the University Medical Center Goettingen, was published today in medical journal The Lancet, and should enable other surgeons to perform similar surgeries.
“So far, bionic reconstruction has only been done in our centre in Vienna,” explained Aszmann.
“However, there are no technical or surgical limitations that would prevent this procedure from being done in centres with similar expertise and resources.”
Injuries to the brachial plexus can be very damaging, and are surprisingly common. Almost 5% of motorcycle and snowmobile accidents cause damage to the nerve group, and a 2010 study of Canadian football players found 26% received brachial plexus injuries in the season.
As a result, the surgery is extremely promising, and could boost the quality of life of many people.
However while promising, only the long-term use of the prosthetics by the three men will determine its level of success.
In a comment piece also published in The Lancet, Professor Simon Kay the surgeon who performed the UK’s first hand transplant, and Daniel Wilks from Leeds Teaching Hospitals NHS Trust, urged caution.
“The present findings – and others – are encouraging, because this approach provides additional neural inputs into prosthetic systems that otherwise would not exist,” they said.
“However, the final verdict will depend on long-term outcomes, which should include assessment of in what circumstances and for what proportion of their day patients wear and use their prostheses.
“Compliance declines with time for all prostheses, and motorised prostheses are heavy, need power, and are often noisy, as well as demanding skilled repair when damaged.”
Images and video courtesy of The Lancet.