# A Novel Wearable Foot and Ankle Monitoring System for the Assessment of Gait Biomechanics
## 4 Discussion
Considering the targeted bandwidth, i.e., 150 Hz which accounts for both muscular activity and the activation pattern of the investigated muscles, high-frequency motion artifacts and stray interference are attenuated inherent to system operation. Low-frequency long-term baseline artifacts will be suppressed by DC and low-frequency rejection. Low-frequency short-term baseline artifacts on the other hand, as well as contact noise, will determine instantaneous alterations of the extracted feature amplitudes. Nevertheless, considering their relatively short duration, they can be identified and ignored for one gait cycle. The proposed solution for the gait monitoring system is also envisioned for employment in the identification of some pathologies. This aspect was illustrated and validated with tests reproducing pathological walking and is discussed further on. When the ankles are disabled because diseases or weak extrinsic foot muscles, the movements of the foot are larger and the foot overpronates. The COP travels inwards and the ankle movers, mainly the tibialis anterior, will be overactive to compensate the deficiencies mentioned above. Muscle fatigue sets in early and can be identified through EMG. If in standing posture the ankle has a 90\({}^{\circ}\) position, the foot is in a neutral position-neither pronated nor supinated, and the foot muscles work coordinated, we expect that the proposed monitoring system will record a normal COP progression line. If however the standing posture faces pronated or supinated foot, imbalances in extrinsic foot muscles, or even unhealthy shoes, one will visualize deviations or even absence of pressures throughout the footprint areas that are monitored. Alterations in the frontal plane mechanics of the foot can as well be assessed with the proposed monitoring system. Findings may indicate either towards faulty foot posture-assessed with the pressure sensors deployed onto the shoe insole, or to shank muscle imbalances-highlighted by EMG. As mentioned earlier, based on kinetic link principle, the human body must be considered in terms of a series of interrelated links or segments [28]. Alterations in the frontal plane mechanics of the foot have been linked to foot and ankle injuries, knee pathology, alterations in the hip muscle recruitment strategies, and may be associated with lumbosacral dysfunction [56]. Spine faulty posture and lumbosacral dysfunction may be associated with foot faulty posture as well as ankle and foot dysfunction. Considering that the ankle and foot musculoskeletal complex is implied in the ankle joint strategy--a strategic element of balance control with implications in stance and gait, the functional evaluation of the foot is essential. Our system contributes to functional evaluation of the lower limb, ankle and foot, during a functional movement, the gait. Along with disease prevention, limitations is important for rehabilitation purposes as well. Further on, it might be useful for body functional movements training and to control the correction of the foot by orthotic insoles. This paper presented a laboratory proof of concept for a wearable gait monitoring system, with the novelty consisting in the underlying software application which correlates plantar pressures with lower-limb EMG and performs gait analysis based on a gait map. Tests performed in the laboratory environment validate the proposed solution for the discrimination of physiological from pathological walking. As such, the next steps aim toward miniaturization and the integration of the proposed system concept into a wearable and portable device, and to undergo cohort studies in clinical environment. Conceptualization, P.F. and M.-A.F. ; methodology, P.F., L.G. and S.H. ; software, P.F. ; validation, L.G. and S.H. ; investigation, P.F. and M.-A.F. ; resources, M.-A.F. ; writing--original draft preparation, P.F., L.G. and M.-A.F. ; writing--review and editing, S.H. ; visualization, S.H. ; supervision, S.H. ; project administration, S.H.