The aim of this case study was to compare the distribution of pressure, during dynamic activity, in three different one arm drive wheelchairs.  The wheelchairs chosen for the study included an Action 3 Lever Drive, an Action 3 Dual handrim, and a prototype Neater Uni-wheelchair.  The Neater Uni-wheelchair was a standard Action 3 wheelchair to which a kit had been attached to convert it into a one arm drive.  Early work by Mandy et al (2007;2009) reported that wheelchairs with such a kit attached  were ergonomically more efficient, and preferred by users.

Pressure distribution was measured using the CONFORMat® Pressure Measurement System which was applied to each wheelchair in turn.  CONFORMat® is a portable interface pressure mapping system which captures seat and back pressure distribution and contact area. A non-disabled user, following familiarisation with each wheelchair, was asked to navigate a course which included driving indoors and outdoors around obstacles, an incline and over different surfaces.  The distribution of pressure between the buttock/sling seat interface was measured during this dynamic activity. Rest periods between each circuit enabled heart rate to return to resting state.  Time taken to complete each circuit was measured.

Results indicated differences in peak pressure V time between the chairs. The measurements focused on variations during speed tests and manoeuvrability tests.  Distribution of pressure at the beginning and end of each trial was significantly greater in both the lever drive and dual handrim, indicating the increased effort needed to commence and cease propulsion. Speed trials highlighted the shift in users’ position on the seat. Asymmetry was markedly different in both the lever drive and dual handrim chairs.  From a clinical perspective, the findings focus on the importance of ergonomics and propulsion. The changes in position and the subsequent pressure distribution may compromise therapeutic positioning, may increase the risk of pressure sores in the sacrum and ischial tuberosities, and results in an asymmetric posture with potential longer term associated impairments .   The initial stage of propulsion and manoeuvrability are often the most difficult tasks for users of one arm drives chairs to master.

The implications of this finding may be the difference between successful independent mobility and the need for attendants.