The biophysical properties of plantar callus and the relationship between pressure and callus development and regression

Wright, CRF

Abstract

Plantar calluses are common skin lesions which often require professional treatment by podiatrists. They commonly present under prominent areas such as the metatarsal heads and can cause significant discomfort during ambulation. Furthermore, they are one of the known risk factors for ulceration in individuals with systemic conditions such as diabetes mellitus. Anecdotal evidence suggests that mechanical factors contribute to calluses and there are numerous studies linking callus to increased peak plantar pressure. However, whether callus is a result of increased pressure or vice versa remains unclear. Skin on other areas of the body has been shown to respond to external loading forces, but no research has specifically investigated the relationship between callus and pressure.
A critical review of the literature explored the methods used for skin profiling through biophysical skin measurement. Skin hydration, distensibility and topography were revealed to be useful measurement parameters to characterise plantar skin and for this study, three devices were chosen for testing these parameters. However, as these devices have not received much attention for testing plantar callus in previous research, the first study investigated their repeatability on normal and callused plantar skin. These devices were shown to provide adequate measures of skin properties so they were then used in a larger scale study investigating the biophysical characteristics of normal and callused plantar skin. It was found that callused skin was less hydrated, less distensible, and rougher in texture than normal plantar skin.
Work was then undertaken to develop a device that could apply loads to plantar skin in a safe manner so that the skin’s response to external loading could be assessed. A subsequent pilot study was conducted to assess whether normal plantar skin in individuals prone to callus would display callus-like skin changes as a result of increased vertical pressure applied by the skin loading device over a minimum period of six weeks. After the skin loading period, no effect could be observed in normal plantar skin properties. The reasons for this are explored in depth. A study was then undertaken in order to assess the effect of plantar pressure reduction in callused skin over a period of 12 weeks. Pressure reduction was achieved by using customised insoles worn by the study participants. No change in callused skin properties was observed and the reasons for this are explored in depth. These studies provide a strong starting point in understanding the link between pressure and callus and provide a foundation for further research.

Citation

Wright, C. (in press). The biophysical properties of plantar callus and the relationship between pressure and callus development and regression. (Thesis). University of Salford

• Thesis Type: Thesis
• Acceptance Date: Nov 4, 2015
• Deposit Date: Jan 18, 2016
• Publicly Available Date: Jan 18, 2016