Development of a Master Socket for optimised design of prosthetic socket for lower limb amputees

To avoid the trauma of a badly fitting prosthetic device, EU researchers developed a ground-breaking mechatronic system to optimise socket design for lower-limb prostheses.

Unique to every individual, the anatomical profile of the residual limb sets the scene for the function of a lower limb prosthesis. Normally, this is a highly subjective and time-consuming process. A feel-and-touch approach is required during adjustment on the amputee where success depends on the ability of the prosthetist.

Rapid, tailor-made socket in leaps and bounds

The EU-funded project SocketMaster first developed microsensors for measuring pressure, friction, and temperature at the interface between the residual limb and the socket in both static and dynamic situations.

Dedicated data acquisition firmware manages the sensors with data communication established between different modules. Included is a mainframe for hosting the residual limb and the loading apparatus to support the patient’s weight. The team incorporated adjustability and an associated procedure for donning and doffing for patients.

“During simulated walking tests, the pressure, friction and loading information is processed for optimised socket design,” explains Dr Jianxin Gao of TWI Ltd, project coordinator. He continues: “The design process can be completed within two hours after activity tests, and the resultant digital 3D data allows manufacture by a rapid prototyping machine for fast fabrication, each for a specific patient.” There is also a user-friendly interface to navigate the system and manage the collected database.

Trials and tribulations during development

The SocketMaster system was tested on six above-the-knee amputees. Patients participating in the clinical trials reported that the system is safe and easy to use, without fatigue, and the feeling of the pads on the leg were not unpleasant.

“During testing and evaluation stages, the sensor pad’s adjustability to cope with different stumps had a relatively small range while some sensor pads tended to collide each other,” outlines Dr Gao. “Moreover, the loading apparatus showed unexpected tilting movements and the communication between different modules was lost because of damaged cables.” Malfunctions were fixed by tightening the screws and testing the system only in the standing position as well as replacing the broken components. “However, the time lost prevented us testing the system on more patients within this project,” notes Dr Gao.

Towards commercialisation and the future for SocketMaster

The team submitted a comprehensive business plan for a two-year fast track to innovation (FTI) proposal for SocketMaster-2 starting in 2019. If successful, the consortium will pursue commercial development of the technique so that, after two years, a joint venture company will be set up to take it to market. Keen interest in the technology has also been expressed by representatives from the National Health System and the armed forces in England.

In the absence of an FTI project, relevant partners will invest their own resources to carry out system improvement and further clinical trials. “With additional clinical trial results, we will be in a better position to approach to venture capitals to seek further investment,” Dr Gao points out.

“Although the system is still far from commercialisation, SocketMaster demonstrated the feasibility of designing a socket within a few hours by taking into account the different load bearing capacities of different segments of the residual limb at least in a standing position,” sums up Dr Gao. Details of the project work can be seen in the project video.

Reference source: Development of a Master Socket for optimised design of prosthetic socket for lower limb amputees