Sensate and insensate in-shoe plantar pressures

In the individual with loss of protective sensation, the presence of high plantar pressures has been considered a risk factor for the development of plantar ulceration. Previous studies of insensate plantar pressures have measured a limited number of isolated, barefoot steps in a laboratory setting. Such isolated snapshots of barefoot plantar pressures do not give us insight into possible step-to-step variations or what plantar pressures occur when wearing shoes. The purpose of this study was to quantitatively examine and compare in-shoe plantar pressures during continuous walking by normal sensate and diabetic insensate subjects. A portable, insole data-acquisition system was used for pressure measurement during 4 minutes of normal continuous walking. Seven pressure sensors were placed in each insole under posterior and anterior heels, the metatarsal heads, and hallux. Twelve sensate and five insensate subjects were studied. We found that the insensate group had higher plantar pressures under posterior and anterior heels and the first metatarsals compared with the sensate group. From the study of the coefficients of variation, we demonstrated a larger step-to-step variation in plantar pressures for the insensate during continuous walking, suggesting the need for caution in interpreting the data from isolated force plate steps when studying insensate individuals.