An investigation of forefoot plantar pressures and plantar thermal characteristics in the diabetic foot

Abstract

Background: Various studies have been conducted with regards to the various factors that may lead to foot ulceration. As a matter of fact, high plantar pressures during walking and high skin temperature contribute to the development of foot ulcers and foot ulcer recurrence (Fernando, et al., 2016). However, although these two modalities are being increasingly used in clinical practice, these two modalities are invariably investigated separately. There is currently a research gap, with few studies investigating the relation of these two emerging modalities together, to investigate whether one affects the other. Aim: To determine whether there is a relationship between forefoot plantar pressures and plantar thermal characteristics in the diabetic foot. Methods: A prospective, quantitative non-experimental study was conducted. Forty-eight participants were divided into four groups namely Group A (Healthy Adults), Group B (Healthy Diabetics), Group C (Participants with Peripheral Arterial Disease) and Group D (Participants with Neuroischaemia). For each participant in each individual group, both feet were analysed, thus a total of 96 limbs were investigated. Foot pressure mapping utilizing the 2-step protocol was employed to obtain the peak plantar pressure. Thermographic temperatures of the plantar aspect of the foot were also recorded following 15 minutes of moderate exercise. For both modalities, five specified regions of interests were taken into consideration (Hallux, 1st MPJ, 2nd to 4th MPJ, 5th MPH and Heel). Results from both measures were then related together. Results: A significant relation (p <0.05), in most cases was noted between plantar pressures and plantar infrared temperatures and this was further confirmed when all the 96 limbs, 24 limbs from each respective group, were assessed together (p=0.00). Furthermore, the scatter plot diagrams all followed an uphill trend and the data points where clustered close to the regression line, indicating that a positive correlation co-efficient is present. In addition, plantar pressures and plantar infrared temperatures exhibited in the complications group were significantly higher than those of the healthy group. Conclusion: Results from this study affirmed that in most cases there is a strong correlation between plantar pressure and plantar infrared temperatures at the regions of interest, implying that an increase in plantar foot pressures will result in higher foot temperatures. Moreover, plantar pressures and plantar infrared temperatures exhibited in the complications group are significantly higher than those of the healthy group. Both these modalities, illustrate an important transfer from subjective to objective evaluation of the high-risk patient and this study acts as a red flag to start appropriate podiatric care long.