FREQUENCY CONTENT OF NORMAL AND DIABETIC PLANTAR PRESSURE PROFILES - IMPLICATIONS FOR THE SELECTION OF TRANSDUCER SIZES

How small do pressure transducers need to be in order to faithfully me asure the plantar pressure profiles (PPPs) under normal and diabetic f eet? In this study, pressures were collected from five diabetic and si x non-diabetic subjects using a commercial measurement system with 25 mm(2) transducers. Discrete Fourier Transform techniques were then use d to determine (i) the spatial frequency content of diabetic and non-d iabetic PPPs, and (ii) the effects of quadrupling the transducer area (from 5 mm x 5 mm to 10 mm x 10 mm). When the data were filtered to re present the effects of using 10 mm x 10 mm transducers, it was found t hat the ensuing reductions in peak pressure in the toe region (50 kPa) were significantly greater than in all other regions of the foot (p < 0.95). There was a significant correlation between pressure underesti mations and measured peak pressures in the metatarsal regions. Based o n data collected with 25 mm(2) transducers it was concluded that trans ducer sizes greater than 6.36 mm x 6.18 mm (medio-lateral and antero-p osterior directions) would result in sub-optimal sampling of PPPs. Cop yright (C) 1996 Elsevier Science Ltd.