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Abstract
The primary role of a wheelchair seat cushion is to provide an effective platform from which the user may perform a wide range of tasks. For many users, the cushion performs a crucial function by reducing the concentration of pressure in soft tissues, thereby helping to prevent the formation of pressure ulcers. Theoretical and experimental data has shown that a properly fitted contoured cushion would improve the pressure distribution and reduce tissue distortion. It is desirable to develop a new approach for designing contoured cushions which not only are available off the shelf but also provide a more intimate fit to the body than standard precontoured cushions.
Our preliminary study on a group of seat support interface shapes suggested that body-seat interface shape patterns could be identified using cluster analysis. Four distinct generic shapes were identified for a group of elderly subjects by analyzing the dissimilarity in geometrical shape parameters. The results support the notion that multiple generic shapes exist and that classifying interface shapes provides meaningful information with respect to the geometrical shape parameters. Furthermore, the generic shapes can potentially be used to design generic shape contoured (GSC) cushions, which could provide an alternative to the custom contoured seat cushions and precontoured seat cushions. GSC cushions would be fabricated by carving generic shapes into high resiliency polyurethane foam. However, the interface shape data used in the preliminary study was obtained from the Electronic Shape Sensor (ESS) when the subject's body was supported by an array of probes. Since the mechanical properties of the support surface is one of the major factors that results in interface shape, the generic shapes derived from those interface shapes did not characterize the body-cushion interface. To date, a practical clinical method of measuring body-cushion interface shape has not been reported for typical cushion materials (e.g., foam). The only device that is portable and can be placed between the subject and the cushion was described in Yamazaki's 1992 paper. Unfortunately, such a device is not commercially available. Therefore, in order to investigate generic shape contoured approaches, the development of an efficient and easy-to-use device for rapidly capturing the body-cushion interface shapes is essential. (Abstract shortened by UMI.)
