Modernising trans-radial prosthetic socket creation with digital methods

It is estimated that globally 20-25% of all amputations are upper-limb, and approximately 1 in every 2500 children are born with upper-limb deficiency. Despite this, advances in upper-limb prosthetics, in particular the socket, have been slow and currently patients are often left with unsatisfactory and unreliable devices. The socket is a crucial part of the prostheses - it must be unique, comfortable and appropriate for the amputee's lifestyle. Socket-fitting is time-consuming and requires several visits to specialised clinics, often far from home. Currently, manufacturing sockets is extremely laborious and takes up lots of clinician time.
Myoelectric (electronically operated) devices are a sub-type of upper limb prostheses that are not currently funded on the NHS. To use a myoelectric hand, the prosthetic socket must have electrodes which detect nerve impulses under the skin. The signals from the nerves are the 'instructions' to the prosthetic hand. Short term illnesses and water retention can cause significant changes in limb volume and therefore poor-fitting sockets; this contributes to low-quality signals and unpredictable reactions from the prosthetic hand, which can cause amputees to abandon their devices entirely.
Multiple systematic reviews of the prosthetics field have highlighted a need for more clinically validated studies into novel socket designs. Several novel upper-limb socket designs exist, but often have only been tested for their effect on the factor they were designed to improve, or not tested clinically at all.

Research Aim: The aim of this research is to take a holistic approach to creating and testing a novel design of upper limb socket. The research goals of the project can be categorised to:
I. Use modern manufacturing methods to create a novel upper-limb socket that includes adjustability, myoelectric control and anatomical contouring.
II. Test the socket with volunteers to see its effect on the electrode-body and socket-body interfaces.
III. Incorporate a feedback mechanism into the socket using sensor technology, to assess and quantify the effects on the remaining limb of having an adjustable and optimised socket design.
Objectives: A digital method of creating sockets will be devised utilising 3D scanning, 3D printing and modern materials to reduce the time and cost it takes to create a socket using traditional processes such as casting and lamination. The effects of different socket modifications will be assessed for their impact on control, comfort and patient satisfaction through a series of prototype designs and test rigs. A prototype adjustable socket will be created based on various existing socket designs and tested with volunteers experiencing trans-radial limb loss/deficiency. Using the feedback from the volunteers, the design will be refined and adapted to include electrodes for myoelectric control. Volunteers will be recruited for a study to compare the novel socket against a traditional socket to show whether myoelectric control reliability, comfort and other factors are improved with the novel design. After refining the myoelectric socket, various sensors will be included in the design as a feedback mechanism to help quantify the effect the novel socket has on the limb.