After several years of prototype development and clinical investigation, researchers at the Department of Bioengineering at Imperial College London published details of a reconfigurable and adaptive liner designed to improve the fit of prosthetic limbs in Nature Communications earlier this year.
Most prosthetic limbs are typically attached to the body of an amputee using a custom-made prosthetic socket with a liner in between the limb and the socket to improve comfort. Throughout the lifetime of an amputee, the residual limb will change shape for a variety of reasons generally requiring the manufacture of an entirely new custom-made socket. To address this issue, an adaptive liner known as the “Roliner” (short for robotic liner) has been developed to offer amputees the ability to change the shape, volume, and stiffness of the liner by using AI to adjust the socket fit.
Roliner is made from silicone. The liner (produced by Unhindr) works by using AI to read real-time data from small sensors placed outside the prosthetic socket. Roliner learns the wearer’s comfort preferences over time and adjusts the liner’s fit by filling or emptying microchannels with tiny amounts of fluid. Amputees will be able to tweak the liner in real time to provide a more comfortable and personalised fit by using their smartphone.
The technology addresses prosthetic fitting challenges as well as opening up possibilities in other fields. Beyond prosthetics, the researchers envision its use, for example, in enhancing the flexibility of rehabilitation exoskeletons.
Whilst it is anticipated that the initial cost of the Roliner will be higher than that of a “passive” liner, there are likely to be costs savings by reducing the number of socket replacements required as well as the clinic time needed to fit new sockets. We would expect users to have fewer difficulties with fit, so less chance of skin irritation and even skin breakdown, especially where there is fluctuating volume. For lower limb amputees, it would follow that they need less time “off their legs” and using a wheelchair.
Further validation is likely to be required, but initial indications are that the Roliner could be available for use in the UK as soon as the end of 2025. We have no information on price or how widely or quickly this will be available and, most importantly, what prosthetists and patients will make of it.
We will be keeping a close eye on this. Watch this space!