An "intelligent" wireless prosthetic liner could allow clinicians to quickly and accurately assess and optimize socket fit at the outset and could also monitor changes over time, alerting patients of the need to adjust their socket or activities to prevent ulcers from forming. (Credit: Diabetes UK/Flickr)

amputation

‘Smart’ liner detects how leg prosthetics fit

A new device could help relieve the pain and discomfort experienced by thousands of amputees as a result of poorly fitting replacement prosthetics for lower limbs.

Researchers are developing a prototype of an “intelligent” prosthetic liner that uses integrated pressure sensors and could be available to patients in as little as three years.

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The sensors for the device measure the pressure and pulling forces at the interface between a patient’s stump and socket of their prosthesis. In excess these pressures can cause tissue damage, leading to painful sores.

“Socket fit is the single biggest factor determining whether prosthesis will be successful for a patient,” says Liudi Jiang, a senior lecturer at the University of Southampton.

“If we had a simple way to accurately measure the load at the socket-stump interface and determine the best possible fit for that limb, it would completely transform the socket fit experience for amputees.”

“Mechanical forces during physical activities of the amputee can lead to breakdown of soft tissues at the stump, which can prove very difficult to heal and will inevitably result in distress for the patient,” says Professor Dan Bader, an expert in tissue biomechanics and developing sensors designed to assess skin health.

Other intelligent materials

There are 50,000 lower-limb amputees in the UK, most of whom use artificial limbs that are attached to the residual limb through a socket. No two stumps are exactly the same shape and size and even an individual’s stump can change shape over the course of a single day.

Pain, discomfort, and ulceration are frequently experienced at the socket interface due to poor fit. This stems from the excessive build-up of pressure within the limb socket (causing high “loads” on the stump).

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, patients with artificial limbs face difficulty in fitting replacement limbs and the outcomes vary.

The intelligent liner will allow clinicians to quickly and accurately assess and optimize 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 centers, giving them a better quality of life and at the same time reducing healthcare costs.

In the future, 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.

The Biomedical Catalyst, a program jointly managed by the Medical Research Council and Technology Strategy Board, is funding the research.

Source: University of Southampton

 

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