A Proof of Concept for a Wireless Ambulatory Weight Bearing Measurement System in Rehabilitation and Telerehabilitation Applications

Weight bearing is an important clinical variable for rehabilitation specialists. The objectives of this proof of concept study were to design and build a wireless system for weight bearing measurement that would provide accurate dynamic and static measurements of plantar forces from multiple sites. The proposed system consists of two shoes instrumented with miniature load cells connected to ankle modules for wireless communication to a computer and signal conditioning. Force plates were used as the gold standard to evaluate the accuracy of the proposed system during quiet standing, walking and weight-shifting tasks in 30 young subjects. The performance of the system was characterized for each task using the following variables: percentage of body weight (PBW), heel-strike (HS) peak force value, stance time (ST), double support time (DST), excursion of center of pressure (COP) in the anteroposterior axis (ACOPx). For the measurement of the PBW, the standard deviation of errors in comparison to data obtained from forces plates during quiet-standing and weight-shifting activities was between 3.96% and 5.13%. With respect to gait parameters, the standard deviation of errors for the measurement of the peak forces during walking was between 6.10% and 8.82% for both shoes, and errors on timing variables during gait cycles were small (less than 18 msec for one standard deviation). For the ACOPx during a front weight-shifting trial, the standard deviation of errors was 19.20% for the right foot. The accuracy of the proposed system offers acceptable performances in the context of its proposed clinical applications. The envisioned embodiment and use of the system are instrumented shoes individually calibrated to assess in combination with real time video from videoconferencing codecs weight bearing capabilities in the context of telerehabilitation care. Work on the integration of the system with a clinical system for telerehabilitation is on-going.