Embedded load-monitoring safety device for osseointegrated lower-limb amputees

Abstract

As a solution for restoring lost limbs and giving back mobility to amputees, prostheses have been developed. Even though there has been an increment of the population of amputees, modifications on the prosthetic limbs on the market have been minimal, and systems developed more than 50 years ago are still on the market. Nowadays, the attachment to prosthetic limbs used mostly is through a socket, another solution to the connection of prostheses involves osseointegration. Unlike sockets, osseointegrated systems are key for restoring the lost limbs and mobility. A wider understanding of the use of such devices and a deeper knowledge regarding the interaction of the user and the prostheses are necessary in order to improve prosthetic limbs. The purpose of this thesis is the design and development of a mechatronic system capable of acquiring signals from the osseointegrated implant to the attachment of the prosthesis in order to know more about the torsion, axial and bending forces interacting between the prosthetic limb and the implant system. For the system developed in this thesis it was necessary to consider:  the current design for attaching the osseointegrated implants,  the modifications to be done for adapting the system,  the selection of sensors to measure the forces,  and the design of the electronic system (including the instrumentation of the sensors, the acquisition of the forces measured). The system developed for measuring the forces has been tested when different kind of loads are applied to the device (bending moment, torque and axial loads), a software analysis of the program has been reviewed, as well as the power consumption of the system during operation. The results of the tests are promising and represent a significant step towards the development of a device capable of measuring the forces for osseointegrated implants.