Disability statistics suggest that 1 billion people (around 15% of the world’s population) are living with a physical disability and around 190 million adults have a major functional difficulty. In contrast, the number of amputees and individuals born without limbs who gain access to prosthetics to restore movement or function is very small.
The vast majority of those who are physically disabled have little to no access to modern prosthetics (artificial hands, arms or legs), nor do they have access to the skills or resources to fit them despite recent advances in prosthetics.
In developing countries, the financial and logistical barriers to obtaining bionic limbs are especially high. The only option for many who are disadvantaged is to obtain prosthetics (artificial arms, hands and legs) that replace the limb but provide no voluntary movement.
Myoelectric limbs are the next step for many amputees. In this situation, a battery and electronic system (functional electric stimulation) is used to create muscle and nerve movement in the residual limb. In this situation, a prosthetic hand is controlled by muscle signals that enable wrist flexors and extensors to close and open the hand. Nowadays myoelectric hands enable a person to move each finger individually in response to signals from electrodes placed over muscles in the upper arm. If muscle signals can’t be used to control the prosthesis, then different types of switches are used. A greater number of tasks are possible with the use of sensors and motorised controls.
Prosthetics that use myoelectric sensors are increasingly affordable. Companies like Open Bionics design their prosthetic hands to be ‘open source’ so they can be built from parts made on commercial 3D printers. Electronic signals can be delivered by relatively cheap, off-the-shelf chips. However, the user’s level of control is very reliant on the fit between the stump and the prosthetic. The sensors must sit on the right areas of skin.
In some cases, procedures may be undertaken to reconnect nerves (those that would normally be connected to arm muscles) to the pectoralis muscles. As the individual thinks about moving their arm or hand, they flex the pectoralis muscles and this movement is picked up by external electrodes that send a message to the prosthetic that the person is wearing. Similar techniques of targeted muscle re-innervation (TMR) are used to control the movement of leg prostheses. However, myoelectric sensors tend to work better in hands and arms than in legs because the movement of knees, feet and ankles is more autonomous and less consciously undertaken.
Current research is focused on either improving (1) the design of prosthetic limbs and socket technology or, (2) the design of osseointegrated prosthetic systems that join the prosthesis to bone.
Unfortunately, there are few prostheticians even in large cities (practitioner numbers are not increasing) and many appointments are sometimes needed to customise prostheses. After an early consultation and a long wait, the stump has sometimes changed in shape or size due to weight gain and even the best-designed sockets can slip and cause discomfort and pain (especially on lower limbs). For this reason, there is growing interest in osseointegration or bone anchored prostheses.
Introduced in Sweden in the 1990s, osseointegration requires less follow-up appointments than standard prostheses and most people a much improved quality of life. For transfemoral amputees (i.e. amputations that pass through the femoral artery), research has shown that bone-anchored prostheses deliver the best hip and pelvic motion when a person is walking, better perceptions of vibration, improved comfort while sitting, and better overall functionality. However, post-operative infections and phantom pain in the vicinity of missing limbs are key issues yet to be resolved. Stress is also felt where the osseointegrated prosthetic implant interfaces with residual bone.
Researchers are focused on any potential failures in the osseointegration that might come about due to stress in the vicinity of the bone integration. Understanding whether this stress increases or reduces when different prosthetic designs are used is a priority. Research is also ongoing to identify ways to resolve phantom pain. There is some evidence that neural sensory feedback e.g. sensations of knee motion and the sole of the foot touching the ground can decrease fatigue, increase walking speed and also reduce the phantom limb pain (Petrini et al, 2019, Nature Medicine, 25).
Delivery of genuine bionic mobility is no doubt the most desired outcome – a prosthetic limb that smoothly integrates with the person’s neuromuscular system and brain to enable movements such as flexing, bending and grasping.
Bionic mobility is achieved through the interaction of thought, action and response. For sustained movements (bionic mobility), microelectrodes are implanted in specific areas of the motor cortex to give the strong signals needed to control bionic limbs. A new electronic pathway connects the mechatronic limb with the brain and peripheral nerves are bypassed. Research in the field of bionic mobility is advancing across different continents, but consumer access to thought-controlled mobility trials and related technologies is still limited.
Winners of the Bionic Mobility Challenge will deliver a ‘nextgen’ innovation with practical benefits for health consumers in one of the following areas:
Prosthetics design, manufacturing and their human integration (e.g., osseointegration aligned with bionic mobility solutions)
Bionic mobility enabled by one or more technologies (existing and emerging) e.g. myo-electrics, sensory electrics, brain-machine interfaces, optogenetics, robotics and artificial intelligence.
Personalised computational neuromuscularskeletal models that use finite element modelling, smart wearables and machine learning to deliver bionic mobility solutions
Exoskeleton and robotic innovations interfaced with bionic mobility solutions
Bionics Challenge 2021
This years Bionics Challenge, delivered in partnership with the Motor Accident Insurance Commission (Qld) has an overall $300,000 in combined Cash Prizes, Mentoring and Acceleration.
Motor Accident Insurance Commission
The Motor Accident Insurance Commission (MAIC) Queensland is our major funding partner. The rehabilitation of Queenslanders impacted by road accident trauma, disabilities and chronic health conditions underpins our highly valued partnership.