Prostheses are useful tools that can restore the ability to pick up and grasp objects and assist the user’s sound hand. A bionic arm works by picking up signals from a user’s muscles. ‘Targeted Muscle Reinnervation’, usually referred to as "TMR" is a surgical procedure for high level arm amputees that takes nerves previously dedicated to hand, wrist or elbow motion, and rewires them into adjacent muscles, dramatically amplifying the nerve signals with the goal of providing users with "thought control" of their myoelectric prosthesis.
When a user puts on their bionic arm, special sensors detect tiny naturally generated electric signals and convert these into intuitive and proportional bionic hand movement. The bionic hand is controlled by tensing the same muscles which are used to open and close a biological hand. To close the bionic arm’s hand, and perform the selected grip, the user imagines flexing the wrist inwards while pulling the fingers into the heel of the hand. To open the hand, the user imagines extending the wrist with an outstretched palm.
Users are normally able to control their bionic hand within just ten minutes, whereas some require a little more rehabilitation to strengthen their muscle sites. The technology fitted inside the bionic arm is known scientifically as electromyography:
and the special sensors are electromyographical, or EMG, electrodes. Myoelectric bionic arms are plug and play, meaning users can take their bionic arm on and off with ease. The arm has an adjustable dynamic socket for comfort. No surgery is required; the medical team identify a user’s strongest muscle sites and take a 3D scan or cast of their residual limb before custom building the arm.
Bionic arms give users proportional control and multiple grip modes. The bionic hand will move more slowly when your muscles are tensed gently, and will move more quickly with firmer tension. This control can be useful for manipulating small or delicate objects, such as eggs or ball bearings.
Amputees in the UK are now able to access these life-changing bionic arms, which can mimic real hand movements, from the NHS. The NHS provided bionic arms are controlled by electrical brain signals and have multi-grip capabilities, enabling a greater range of movements to make day-to-day tasks easier.
The technology has been made available following two independent reviews into their use and the successful rollout for veterans. Previously, the cutting-edge prosthetics were only available on the NHS to military veterans injured in service. Prosthetics offered by the NHS previously were basic models, with limited open and close gripping motions, or others were cosmetic with no function.
Eligible patients must have enough residual upper arm muscles to send signals that create intuitive movements, but children as young as nine can use them, allowing them to improve their play and learning. Each patient is carefully assessed to find the right type of prosthetic for them depending on their requirements and capabilities.
NHS chief executive Amanda Pritchard said: “These incredible multi-grip prosthetics have already made a huge difference to veterans and so it is fantastic to be able to offer them to all patients in England who need them. “The arms, for both children and adults, use the very latest tech which will boost peoples’ independence and change the lives of dozens across the country. “The NHS is at the forefront of medical innovation and this rollout is the latest example of how we are adopting the best medical advances for patients”.