Concepts of Pressure in an Ischial Containment Socket: Perception

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Journal of Prosthetics and Orthotics





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The goal of this study was to determine the subjective magnitudes of pressure perceived by a subject who used an ischial containment socket that was self-reported as "comfortable," and to examine the relationships between perceived pressures and actual pressures. A Borg scale of subjective pressure magnitude (Borg G. Borg's Perceived Exertion and Pain Scales . Champaign, IL: Human Kinetics, 1998) was used to obtain quantitative estimates of the pressures. The subject was asked to identify for different regions of the socket the phases of gait during which maximum and minimum pressures were experienced and their subjective magnitudes. Actual pressures were measured using the F-Socket pressure sensing system (Tekscan, Inc., South Boston, MA). Most of the subjective magnitudes reported during gait (temporal) for maximum and minimum perceived pressures in the muscle compartments of the socket tended to be consistent with the actual maximum and minimum pressures. Detection of the phases of gait during which maximum and minimum pressures occurred was correct more frequently (temporal changes in pressure during gait) than the detection of differences in pressure between adjacent compartments during a single phase of gait (spatial differences in pressure). In the regions of high pressure, such as Scarpa's triangle, the ischium, the adductor longus tendon, and the gluteal fold, the subjective identification of phases of gait during which maximum and minimum pressures occurred were less consistent with measured pressures. The manner of loading of the mechanoreceptors (uniform versus a clamping mode of pressure) could explain the differences in perception of the subjective magnitudes of pressure and the apparent underlying psychophysical relationships for different regions of the socket and limb. It was concluded that in a comfortable socket, pressures are not uniform during gait and pressures are not uniform over all regions of the socket. Pressures experienced during static loading cannot be relied upon to indicate what the range of pressures will be and how the socket will feel during gait. Subjective magnitudes may not accurately reflect actual pressures in some regions of the socket. Additional research should be conducted on the relationship between mode of pressure loading (circumferential versus clamping) and perception of pressure, as well as the possible influence of quasi-hydrostatic loading on pressure sensation.


Pressure--Measurement; Pressure transducers; Prosthesis


Biomedical Devices and Instrumentation | Biomedical Engineering and Bioengineering | Civil and Environmental Engineering | Orthotics and Prosthetics




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