Association Between Peak Plantar Shear Stresses and Physical Body Measures




Master, Hiral
Rieder, Stephen
Udofia, Joseph
Adams, Linda
Yavuz, Metin


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Purpose: Peak pressure has been long considered a risk factor for diabetic foot ulceration. Recent studies also indicated shear as a significant pathological factor. Cavanagh et al (1991) demonstrated a significant correlation between body mass and peak pressures in diabetic patients]. However, Ahroni et al (1987) claimed that peak pressure values of heavier individuals may not necessarily be abnormally high. Another physical body attribute, body height, has been associated with step length which depends on anteroposterior ground reaction forces. To our knowledge the literature does not contain any reports that discuss a potential correlation between peak plantar shear stress and pressure and body measures such as body mass, height or presence of neuropathy. The purpose of this study was to explore these relationships using a custom-built pressure-shear plate. Methods: The study was approved by the Institutional Review Board. Subjects gave informed consent before participation. There are three groups: first - (DN) consisted of 14 diabetic neuropathic patients, second - (DC) comprised 14 diabetic patients without neuropathy and third - (HC) healthy control group, which included 11 subjects. Peripheral neuropathy was tested with a biothesiometer. Each subject walked multiple times at self-selected speeds on the stress plate, which was installed on a 12-ft walkway and set flush. Data from three trials were averaged and used in statistical analysis. Two shear stress and pressure variables were identified in each subject; peak shear (PS), peak shear-time integral (STI), peak pressure (PP) and peak pressure-time integral (PTI). These were correlated against the patients’ body mass, height and vibration. Results: Normality assumption was satisfied. Pearson correlation analysis was carried out for each group and each stress and pressure variable. No correlation was statistically significant. Body mass and body height could not account for any degree of variance in PS, STI, PP and PTI. In addition, plantar shear and pressure magnitudes do not correlate with vibration perception in DN group. Conclusion: Thus, plantar shear stresses do not depend on body weight and body height and they need to be measured rather than calculated.


Research Appreciation Day Award Winner - 2015 School of Health Professions - Best Physical Therapist Poster Presentation