Relationship between skin temperature monitoring with Smart Socks and plantar pressure distribution: a pilot study

Objective: Increased skin temperature at the plantar aspect of the foot can predict foot ulceration. However its relation to plantar pressure overload is unknown. The aim of this study was to assess the ability of 'smart socks', monitoring plantar temperature under real-life conditions, to predict plantar pressure distribution. Method: The 'smart socks' have seven thermal sensors woven into the fabric of the sock to measure the temperature beneath the foot in real-life conditions. The upper part of the sock is connected to a central unit through which changes in the sensor resistance is converted into temperature changes. Participants were instructed to wear the socks for three continuous hours. Plantar pressure was measured by the MatScan plantar-pressure measurement system (Tekscan Inc., US). Results: The study included 25 healthy volunteers (11 males, 14 females, mean age was 41.1 years (standard deviation (SD): 17.6) years, a mean body mass index of 29.4 kg/m(2) (SD: 6.95). Temperature changes at sensor (S) five significantly correlated with metatarsal (M) 2 pressure time integral (PTI) (r=0.519, p=0.008), M3 PTI (r=0.435, p=0.03), M4 PTI (r=0.452, p=0.023). Changes at S5 also significantly correlated with peak pressure at M2 (r=0.66, p=0.000), M3 (r=0.52, p=0.01), and M4 (r=0.60, p=0.002). Temperature changes at S6 were significantly correlated with changes at S1, S2, S3,S4, S5, and S7. Conclusion: Temperature changes at the plantar aspect of the foot measured by the smart socks are correlated with plantar pressure distribution. Furthermore, two sensors at positions S5 and S6 were sufficient to predict plantar pressure changes.