Lower limb prostheses have become quite advanced lately, in some cases they have capabilities that rival those of natural legs. Yet, no improvements are of any use if the prosthetic doesn’t quite fit, a common problem for amputees. This is because each amputee’s stump is different and customizing a fitted prosthetic that evenly distributes pressure is one of the greatest challenges in this field. Patients have to work with specialists on getting the shape just right, requiring a team effort that can take multiple iterations to get it fit.
Now researchers at University of Southampton have developed an electronic liner that measures forces at the interface between the stump and prosthetic to help create a better fit. The device has sensors along its surface that create a pressure map of the interior of the socket and can help prevent tissue damage and discomfort. Moreover, because a stump can change its shape throughout the day, the researchers believe the new technology will help lead to adjustable sockets that comport to the wearer’s changing anatomy.
Synthetic liners, worn like a sock over the stump, provide some cushioning against the hard socket, but at present there is no convenient way to accurately measure the critical loads at this interface in the clinic. Without this information, prosthetists face difficulty in fitting replacement limbs and the outcomes for patients are variable.
The intelligent liner will allow clinicians to quickly and accurately assess and optimise socket fit at the outset. The wireless interface will also monitor changes to socket fit over time, alerting patients of the need to adjust their socket or activities to prevent ulcers from forming. This relatively practical and potentially low-cost solution could substantially reduce amputees’ follow-up visits to their rehabilitation centres, giving them a better quality of life and at the same time reducing healthcare costs.
In future, the scientists believe the technology could form the basis for other intelligent materials, for example shoe insoles to prevent diabetic foot ulcers, or mattresses and wheelchairs that protect against pressure sores in immobile or elderly patients.