Temporal redistribution of plantar pressure points in diabetic and control subjects: A time-series analysis of neuro-capillary chaos

Background: In diabetic individuals (DI), neuropathy hinders the redistribution of plantar pressure points thus leading to susceptible areas where there is constant capillary blanching which may develop into trophic ulcers. The redistribution of pressure points may precede evidence of clinical neuropathy. In this study we compare temporal redistribution of plantar pressure points (areas of capillary blanching) between normal subjects taken as controls and DI with no clinical signs of neuropathy. Method: Four adults (45±4.55 years) diagnosed to have Type-2 Diabetes, without signs of clinical neuropathy and age -matched controls (43±3.74 years) were studied. The subjects were asked to stand on a glass slab and a 10 minute video recording of 10 selected plantar pressure points was made. Changes in the distance of these points with reference to a defined point on Mayer's line were measured at every 10 seconds. Standard deviation of difference of redistributed consecutive pressure point (SDPP) in cms., and fractal dimension (FD) was used to compare the two groups. Results: Combined mean SDPP (DI =0.013 ± 0.008 cms, controls= 0.196±0.233 cms, P <0.001) and FD (DI =1.000 ± 0.000, controls= 1.010±0.017, P <0.001) of diabetic patients were significantly lower than controls. Pressure point at base of the 4^th toe and the lower limit of blanching to the left Mayers line at the heel did not differ significantly between DI and controls. Conclusion: There is impaired redistribution of plantar pressure points in individuals with diabetes without signs of clinical neuropathy. This can be attributed to loss of chaos generating mechanisms in DI. Redistribution of pressure points may be essential in the prevention of trophic ulcers in susceptible individuals.