Browsing by Author "Xiong, S"

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    Load distribution to minimise pressure-related pain on foot: A model
    (Taylor & Francis, 2013) Rodrigo, AS; Goonetilleke, RS; Xiong, S
    The optimal force distribution to minimise pain or discomfort at the foot–shoe interface is still not known. Most shoerelated products attempt to distribute the load uniformly without much consideration to the bony and soft tissue regions. An experiment was conducted to first determine the pressure pain threshold (PPT) and tissue deformation on the plantar surface of the foot. Circular probes of areas 0.5, 1.0 and 2.0 cm2 at indentation speeds of 0.5, 1 and 2 mm/s showed that PPT depends on the location stimulated, area of stimulation and the indentation speed. The results also showed that tissue stiffness is quite low for small deformations (,4 mm), but significantly higher at large deformations (.4 mm). The stiffness at the larger deformation region was positively correlated with PPT (r ¼ 0.63, p , 0.001). The data were further used to develop a model with PPT, deformation and stimulated area. Practitioner Summary: Pressure at which there is an onset of pain is higher when a larger area of soft tissue is stimulated. Bony areas may be better suited to bear load on smaller areas to minimise pressure-related pain. Thus, manipulating supporting surface stiffness and surface contours can help minimise pain.
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    item: Article-Abstract
    A Model for the perception of surface pressure on human foot
    Xiong, S; Goonetilleke, RS; Rodrigo, WDAS; Zhao, J
    The psychophysical relationship between the magnitude of pressure on thirteen test locations of twenty healthy subjects’ feet with four probe areas at three indentation speeds and the corresponding perceived sensations were analyzed. The dependency of pressure pain thresholds (PPT) on area, A, and speed, v, can be mathematically modeled in the form, PPTi ¼ [ai þ bLn(v)]Ab i ¼ 1,2.13 where b and b are constants and are dependent on location and gender, and ai is a constant highly correlated with foot tissue stiffness. The relationship between the sensory intensity to pressure magnitude appears to follow a modified Stevens’ power law with power exponents less than 1.0 and consistent across the 13 test locations with a mean of 0.82 and a range from 0.67 to 0.98. This particular model helps to understand the sensation of pressure threshold and its impact in the design of consumer products.