Pressure thresholds and stiffness on the plantar surface of the human foot

Abstract

The objective was to develop a methodology to assess Pressure Discomfort Thresholds (PDT), Pressure Pain Thresholds (PPT), and tissue stiffness on the plantar surface of the foot. Ten male and ten female participants volunteered for the study. Foot landmarks were used to create a standardized grid-type template of 95 points. For each test point, PPT and PDT values were obtained, and stiffness was calculated for each of the twenty participants. Cluster analyses were performed to determine the regions of similarity for the three dependent variables, PPT, PDT and stiffness. Moran's-I-index was used to determine the spatial auto correlations. The use of k-means clustering showed five distinct clusters while the three dependent variables showed strong correlations to each other. Morisita's similarity index was used to check the similarity of the grid among all participants. Both male and female participants showed a Morisita's index greater than 0.7 confirming the reliability of the foot template.Practitioner Summary: Pressure Discomfort thresholds (PPT), Pressure pain thresholds (PPT) and tissue stiffness were evaluated at 95 points on the plantar surface of the foot. The PPT and related PDT map are useful to design the footbeds of shoes. Based on the data collected, five distinct clusters of locations were identified.

The effect of high-intensity versus low-level laser therapy in the management of plantar fasciitis: randomized participant blind controlled trial

“…Pressure pain threshold was measured with algometer (Pain Test FPX 25) using 1-cm² rubber tip on the middle of anatomical site of enthesis zone of plantar fascia to the heel. 10 , 11 Pressure was applied slowly until the participant first felt the pain and responded by saying “stop.” In each heel, there were three measurements taken with 30 seconds break after each measurement. The average of all three measurements in each heel was recorded as a final value.…”

Autoalgometry: An Important Tool for Pressure Pain Threshold Evaluation

“…The finding of a lower pain threshold in young women than in young men ( Figure 3 , Figure 4 , Figure 5 and Figure 6 ) also agrees with the literature data [ 9 , 24 , 25 ]. Several studies reported that men have significantly higher pressure pain thresholds than women [ 1 ].…”

“…These findings suggest a very low pain tolerance for young women and/or high sensitivity of skin nociceptors to mechanical stimuli, leading to greatly increased activity over a small variation of pressure; these hypotheses deserve further study. Moreover, it is possible that women express pain while men holdback emotions of pain [ 1 ]. This aspect represents an important limitation of this experimental model that is based on the personal identification of pain intensity.…”

“…In the first method, people record their personal evaluation of pain intensity on a hypothetical scale with minimum and maximum values (e.g., rating from 0 to 10 or positioning a cursor on a visual scale). Weerasinghe et al [ 1 ] utilized a pain scale to evaluate pain pressure thresholds in their study on the human plantar surface. In the second method, the intensity of the physical stimulus that evokes pain is evaluated; this is commonly called the pain threshold.…”

“…Several studies have described different stimuli to evaluate pain thresholds, such as pressure [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ], heat [ 11 , 12 ], electric current [ 13 , 14 , 15 , 16 , 17 , 18 ], and intra-epidermal injection of chemical substances (e.g., capsaicin [ 19 ] or acid type solution at pH 4.3 [ 20 ]). Despite the fact that the most abundant nociceptors are polymodal, generally different stimuli activate different nociceptors clusters; for this reason, it is important to study all kinds of stimuli to improve all technical aspects of pain threshold evaluation.…”