Quantifying Dynamic Changes in Plantar Pressure Gradient in Diabetics with Peripheral Neuropathy.

Stephanie Burns,Fang Lin,Yih-Kuen Jan,Chi-Wen Lung,Elizabeth T. Hsiao-Wecksler

doi:10.3389/fbioe.2016.00054

Abstract

Diabetic foot ulcers remain one of the most serious complications of diabetes. Peak plantar pressure (PPP) and peak pressure gradient (PPG) during walking have been shown to be associated with the development of diabetic foot ulcers. To gain further insight into the mechanical etiology of diabetic foot ulcers, examination of the pressure gradient angle (PGA) has been recently proposed. The PGA quantifies directional variation or orientation of the pressure gradient during walking and provides a measure of whether pressure gradient patterns are concentrated or dispersed along the plantar surface. We hypothesized that diabetics at risk of foot ulceration would have smaller PGA in key plantar regions, suggesting less movement of the pressure gradient over time. A total of 27 participants were studied, including 19 diabetics with peripheral neuropathy and 8 non-diabetic control subjects. A foot pressure measurement system was used to measure plantar pressures during walking. PPP, PPG, and PGA were calculated for four foot regions – first toe (T1), first metatarsal head (M1), second metatarsal head (M2), and heel (HL). Consistent with prior studies, PPP and PPG were significantly larger in the diabetic group compared with non-diabetic controls in the T1 and M1 regions, but not M2 or HL. For example, PPP was 165% (P = 0.02) and PPG was 214% (P < 0.001) larger in T1. PGA was found to be significantly smaller in the diabetic group in T1 (46%, P = 0.04), suggesting a more concentrated pressure gradient pattern under the toe. The proposed PGA may improve our understanding of the role of pressure gradient on the risk of diabetic foot ulcers.

Highlights

Diabetic foot ulcers remain one of the most serious complications of diabetes mellitus (Burns and Jan, 2012)
We demonstrated that the pressure gradient angle (PGA) provides additional information to quantify the pressure gradient patterns (Lung et al, 2013)
Despite that the Peak plantar pressure (PPP) values of the control and the diabetic subjects were similar (~250 kPa), PPP distributions for controls (Figure 2A) were spatially flatter than diabetic PPP distributions (Figure 2B). These distributions lead to the peak pressure gradient (PPG) as 29 kPa/mm in control and 58 kPa/mm in diabetics, respectively

Summary

Introduction

Diabetic foot ulcers remain one of the most serious complications of diabetes mellitus (Burns and Jan, 2012). Diabetic peripheral neuropathy causes loss of protective sensation and changes in the soft tissues of the foot as well as dryness of the skin that can lead to excessive formation of callus (Burns and Jan, 2012; Jan et al, 2013a,b). These changes affect ambulatory function that may lead to high plantar pressures in diabetics (Lung and Jan, 2012; Jan et al, 2013a). The repetitive high pressure insults to the plantar surface of the diabetic foot have been shown to be associated with the development of foot ulcers (Veves et al, 1992; Bus, 2012; Patry et al, 2013)

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