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

Project Information

SocketMaster

Grant agreement ID: 645239

DOI

10.3030/645239

Project closed

EC signature date 11 December 2014

Start date 1 February 2015

End date 31 July 2018

Funded under

• INDUSTRIAL LEADERSHIP - Leadership in enabling and industrial technologies - Information and Communication Technologies (ICT)

Total cost

€ 3 950 085,00

EU contribution

€ 3 950 084,00

Coordinated by

TWI LIMITED
United Kingdom

Periodic Reporting for period 2 - SocketMaster (Development of a Master Socket for optimised design of prosthetic socket for lower limb amputees)

Reporting period: 2016-08-01 to 2018-07-31

Summary of the context and overall objectives of the project

In developed countries, more than 90% of limb amputees achieve their mobility through the use of prostheses. Nowadays, there is nothing more frustrating to the prosthetic limb users than to be told to stop using their prosthesis because of medical problems. Since the amputees will have to wear a prosthetic limb for the rest of their life, the comfort of a prosthetic limb is the primary consideration for both manufacturer and service providers, as they are keen to help the prosthetic limb users to regain a good quality of life.

The SocketMaster project aimed to develop a new technique for the design of an optimised prosthetic socket for lower limb amputees. This was done by integrating micro sensors into a SocketMaster tool which can help prosthetists to achieve fast customised design and manufacturing of prosthetic sockets for above knee amputees. It had the following main objectives:

1) To develop micro sensors able to measure pressure, friction, temperature and other parameters relevant to the comfort of patients within the interface between the residual limb and the socket in both static and dynamic situations.

2) To develop a framework by assembling the sensors in a SocketMaster tool. The pressure, friction information and loading during simulated walking tests at will be acquired and processed to achieve optimised socket design. The design process could be completed within 2 hours after activity tests, and the resultant digital 3D data allowed manufacture by a rapid prototyping machine for fast fabrication of tailored sockets for a specific patient.

3) To perform clinical trials to validate the SocketMaster technique and procedures

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The project started with the development of a specific type of sensor which is the foundation of the SocketMaster system. The sensor unit was able to measure multiple biomechanical parameters that are crucial to the comfort of a patient wearing a socket.

Afterwards, the sensor unit was further assembled as sensor pad, where a micro motor was connected to control the movement of the pad within a mechanical frame of a Master Socket.

To ensure different posture can be simulated during testing, a loading apparatus was also designed and fabricated. The integrated SocketMaster hardware system, which comprised of a gait loading apparatus and a Master Socket.

The control software of the SocketMaster system is composed of different modules that have been built based on the system architecture . The data collector board uses I2C communication protocol to talk with motors and sensors installed on the socket.

A well-fitting socket requires to take into account the biomechanical property of soft tissue of a patient’s residual limb. To this end, a hand-held device was developed.

During clinical test, the collected data was used for socket design. A Solidworks based approach has been established which generates 3D shape of the stump and then a socket. This approach requires comprehensive manual operations between coordinates, line, curves and 3D shapes. It starts from the coordinate’s matrix of the 47 sensors, and the shape of the entire socket has been reconstructed in a unique model. For the patients with a short stump, the coordinates of the lower ring were not considered because this ring was not in contact with the leg. A physical model that has been fabricated using FDM (Fused Deposition Modelling) Type 3D printing with PETG. It demonstrated that this SolidWorks based socket design approach is working.

The fist clinical trial was performed on a pilot patient in May 2017 at the London Prosthetic Centre (LPC). The test revealed a number of issues that need to be improved for further clinical tests. It took nearly a year to complete the re-assembly of the Master Socket, including software integration. The second clinical trial was conducted in early May 2018 in Greece, then the updated system was shipped to LPC in London again in early May 2018. 14 clinical tests where biomechanical data were recorded had been done on six trans-femoral amputee patients by the end of the project.

The six subjects who participated in clinical trials have an age ranging from 38 to 75 years. They include 2 males and 4 females, 2 left leg and 4 right leg that had been amputated. Some of the subjects participated in the tests on multiple days, with multiple trial tests for consistency analysis.

The clinical test started with the initialization of the micro motors and the loading apparatus, followed by a manual adjustment of the system according to the patient’s biometric characteristics. Afterwards, the system was worn by the patient, and every part was fine-tuned such that the patient felt at an optimal comfort with the Master Socket. Biomechanical data from the 47 sensors were collected and saved in the control laptop. All the biomechanical data were analysed offline, which showed that the sensors provided consistent measurement results. The positional data of the sensor pads and the brim parts were fed into the Socket Master Geometry Maker module. Together with the data of manual adjustments of the brim parts, and a CAD file for a check socket can be produced by using SolidWorks for manufacturing (e.g. 3D printing).

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The final results are:

1) Multifunctional micro sensor system: With this sensor system, the distribution of pressure, temperature and friction of the residual limb at a specific point of gait cycle can be quantified.

2) A SocketMaster medical tool: The SocketMaster tool is able to fit patients with a certain size range of residual limbs. The data collected from the SocketMaster tool can be fed into a prosthetic socket design system, so that an initial prosthetic socket that fits to a standing posture can be designed within a few hours (normally 2h).

3) Residual limb evaluation model: The residual limb of a patient can be evaluated by a hand held device. A biomechanical model of patients’ residual legs was created, which was based on the categorisation by the prosthetists. This model can be used to turn the dynamic biomechanical data collected by the SocketMaster tool during walking tests into an optimised socket for the patient.

4) Data processing software: Various data from the multifunctional sensors can be processed so that an optimal socket design can be achieved.

5) Clinical validation report: This is one of the most important outcomes of the project. It demonstrated that the SocketMaster concept is practical and working, although the system need further improvement to make it more robust.

6) New socket design procedure: A new clinical procedure for prosthetic socket design has been formulated, but it needs further clinical trials to validate.



The SocketMaster project is expected to contribute to

1) Securing and reinforcing European leadership in the microsystem sector, expanding its share in smart systems for medical applications.

2) Seizing new opportunities in addressing societal challenges in health and well-being.

SocketMaster system

SocketMaster trial