Background

Gastrocnemius contracture contributes to the development of many foot and ankle conditions, with prolonged immobilisation leading to muscle contractures. It is also being hypothesised that overnight inactivity can lead to gastrocnemius shortening if the foot is positioned in plantar flexion during sleep.

Through the University of Liverpool KEI Voucher programme, leading academics, Dr Paolo Paoletti (School of Engineering) and Professor Rahul Savani (School of Computing), are collaborating with Wirral-based Foot-ZZ Ltd (run by Professor Lyndon Mason), to undertake a Phase 0 project, with the goal of developing and testing a sensor system to measure foot position, angle and rotation, as well as the body’s core position. This will enable data to be collectable by an individual user and fed back via a mobile device to a central storage database, which can allow for further analysis.

The support from Sensor City has been key to create a proof-of-concept of our idea, that we can finally test on the field.
We hope this is only the first step of a long-standing collaboration with Sensor City and Foot-ZZ to create the next generation of smart sensors for healthcare.

Paolo Paoletti, University of Liverpool

Approaching Sensor City

The sensor system will be composed of accelerometers which will collect the orientation of the limb with respect to the gravity vector and the orientation angle at critical joints. Sensor City was approached to assist with some of the technical elements of the project, following discussions and demonstrations of a similar previous project. Our team of engineers were tasked with producing a second-generation prototype, to improve both size and ergonomics.

Partner Support

We supported the project by developing the hardware system. An initial prototype, using off-the-shelf Inertial Measurement Units, has already been realised by Paolo Paoletti, but Sensor City engineers helped to optimise the prototype, increase its performance and enhance its wearability. Similar sensors to monitor the wrist have also being manufactured to broaden the scope of the sensing system to other musculoskeletal pathologies.

Working into the future

Based on the results and feedback from user testing from this initial Proof of Concept project, the preliminary data collected will show the feasibility of the proposed approach to sleep position monitoring. The next step will then be to design and build a further refinement of the wrist and ankle devices, with the end product also including a commercial app that could be used by medical practitioners to diagnose, treat and monitor patients.

Results

The new prototype is very lightweight and comfortable for the user, preventing its use affecting patients’ sleep. The measurable objective of the project is the production of a validated sleep-monitoring system, along with some preliminary data supporting the hypothesis that there is a correlation between readily collectable sleep position data and musculoskeletal diseases. Such evidence can now form the basis of an extended trial that would establish causal links between limb positioning and musculoskeletal pathologies.

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