Alan Haddow^*, Nigel Shapcott^** and Jess Gonzalez^**
*Michigan State University, ME Department, MI
^**University of Pittsburgh, School of Health and Rehabilitation Sciences, PA

ABSTRACT  This paper reports on the background to and the results of an international wheelchair cushion design competition. The cushions were to be designed for manufacture and use in developing countries where there are ever-increasing problem due to pressure ulcers. A brief description of the various designs is given and references are cited as to where more detailed information can be found.

BACKGROUND  In 1992 the founding members of RESNA's International Appropriate Technology Special Interest Group (SIG-17) decided to focus on a special project to address concerns related to pressure ulcers (sores) that were reportedly becoming an ever increasing problem in developing countries [1]. The project was named Project Sorebutts and addressed both prevention and treatment through three different activities:

The Poster Competition To create an educational poster to make spinal cord injured (SCI) survivors and their caregivers aware of the seriousness of pressure sores and the importance of pressure relief in their prevention.

The Cushion Design Competition To design a wheelchair cushion that is inexpensive, easily made in developing countries, and effective in reducing the pressures on weightbearing areas of the pelvis.

The Spinal Cord Injury Survivors' Manual To produce a manual; which through good graphics, upbeat humor, and practical information; engages the owner in survival strategies. This part of Project Sorebutts is being performed in collaboration with the Wheeled Mobility Center at San Francisco State University [2].

While the development of the SCI Survivors' Manual is still underway, the remaining two parts of the Project have produced significant results. Details of the Poster Competition can be found elsewhere [3]. Here we report on the progress in the development of inexpensive yet effective cushions appropriate for use in developing countries. In particular we shall present the results of the Cushion Design Competition that was judged at RESNA's 1996 annual conference. Attention will focus on a description of the various cushions submitted and the judging criteria used.

OBJECTIVE  The objective of the Cushion Design component of the Project is two fold. The first is to generate a variety of effective cushions and/or seating designs that would alleviate pressure ulcers. The second is to disseminate information on these designs to developing countries, enabling an appropriate cushion to be chosen for the particular location and required application. Moreover, from the information distributed local crafts-people must be able to manufacture any of the designs deemed to be suitable.

METHOD  In order to meet the first objective listed above, SIG-17 has developed an annual competition, Project Sorebutts Cushion Design Competition, with a view to attracting both national and international entrants. In addition to requiring written design and manufacturing instructions, an actual cushion must also be submitted for evaluation and testing. All entrants would then be judged by a panel of experts, and prize money would be distributed accordingly. While the various entries would be rated by the panel, detailed information on all the submissions will be disseminated to appropriate agencies, published on the world wide web, and sent directly to developing countries.

APPROACH  The judging of the inaugural competition was held at the RESNA's 1996 Annual Conference in Salt Lake City, with detailed rules for the competition having been published a number of months earlier [3,4]. An important component of these rules was a set of drawings that would enable an entrant to build a simple, yet anatomically realistic Pressure Measurement Dummy (PMD). This was the same device that would be used by the judges. Detailed assembly drawings of this can be found at the web site [3]. A synopsis of the rules follow:

To design and construct a cushion to fit on or in a wheelchair that has a standard canvas "sling" base and backrest with a seat dimensions of 16" x 16". There were four main judging criteria, each receiving equal weight from the judges. The first was the ability of the device to equalize the pressure acting over the seating area; the second was the cost of the final product; the third was its manufacturability (bearing in mind the availability of local materials and skill levels of the craft persons); and finally there was a category for additional features; such as its fail-safe design, durability and maintenance, ability to be used off the wheelchair, etc.

RESULTS  There were seven cushions in the competition and most were based on a different type of construction. This was particularly welcomed by the organizers because the main purpose of the competition was to generate a pool of unique ideas. A brief description of each of the designs is as follows:

1. A cotton bag was sectioned into three compartments, two of which were filled with beans. Figure 1 shows more details of this design.

2. A 16"x16" frame was constructed from 2"x4" lengths of wood and the space between the frame was spanned by a tensioned weave of cut-up car inner tubes.

3. A three-dimensionally contoured cushioned made from multiple layers of thick fabric sewn together. The contours are chosen to best suit the individual user.

4. This design is perhaps best described as Roho like. A base is made from a lattice of leather and then three bicycle inner tubes are woven through this lattice in an ingenious manner. The inner tubes loop-up through the leather lattice producing a 10x10 matrix of rubber 'pods'.

5. Bicycle inner tubes were also used in this design. Here, eight were partially filled with air and air restrictions were created in each tube by tightly tying short lengths of string around the tube every 10cm. All the inner tubes were then formed into a rectangular shape and placed in a cotton bag. Figure 2 shows a photograph of the cushion without its cover in the process of being tested for it pressure distribution capabilities.

6. A partially inflated beach ball was the main component here. It was placed in a loose cotton bag with an additional tightly rolled piece of fabric placed in front of the ball to act as a support for the femurs and 'bucket' the pelvis [1].

7. The final entrant was similar to design 3 in that it was laminated, but the laminations were made from corrugated cardboard. Each lamination was cut and shaped to suit the individual. A three-dimensional, custom shaped product resulted. A 2" layer of foam was then placed on the seating interface.

Specific details of each of these designs can be found at the web site [3] or by contacting the authors of this paper directly.

DISCUSSION  While the judges were asked to look for an overall winner based on the four judging criteria mentioned above, no one cushion emerged ahead in all the four categories. Indeed, it was finally decided to award two first places. Design 1 scored particularly well in the "manufacturability" and the "cost" categories. Design 5, although a little more expensive and harder to construct than the first, performed exceptionally well in the "Pressure" category and was judged to have more "Additional" features.

The competition is to be held again in 1997 with slight modifications to the rules and minor changes being made to the PMD so that it more accurately represents a human in a seating position. The refinements to the PMD are particularly noteworthy because there is currently no simple, standardized way of loading cushions with an anatomically correct load.

REFERENCES

1. Shapcott, N., et al, (1996), "A Proposed Low Cushion Design for Individuals with Spinal Cord Injury in Developing Countries," RESNA Annual Conference, Salt Lake City, UT, USA.

2. Wheeled Mobility Center, San Francisco State University, School of Engineering, 1600 Holloway Ave., San Francisco, CA 94132, USA.

3. http://www.egr.msu.edu/~haddow/sig17

4. Shapcott, N. (1996), RESNA News, Jan.-Feb., page 9.

ACKNOWLEDGMENTS

The financial help of Vista Medical Ltd.; U.S. Rehab, Pittsburgh; and Jay Medical is gratefully acknowledged. A special thanks goes to Jeff Taylor for supplying and operating the Force Sensor Pressure Measurement System and to Jan Bednarczyk, Dwight Johnson, and Peter Pfaelzer for help with many aspects of the Project.

Alan Haddow Ph.D.
Department of Mechanical Engineering
Engineering Building
Michigan State University
East Lansing, MI 48824
USA