Performance Analysis of Suspension Manual Wheelchairs

Throughout the course of daily activities, wheelchair users are subjected to a variety of whole-body vibrations that are suspected to cause rider discomfort and a number of harmful physiological effects. In efforts to improve comfort and prevent secondary injuries, manufacturers of manual wheelchairs have integrated suspension systems into their designs. The purpose of this research was to provide a thorough evaluation of currently available suspension manual wheelchairs and to determine the advantages, if any, of wheelchair suspension. The evaluation was composed of two sections: 1) a durability and cost analysis of three selected suspension manual wheelchairs; and 2) a pair of functional tests comparing suspension manual wheelchairs to standard folding- and rigid-frame models. The durability and cost analysis revealed that integrated suspension did not significantly improve wheelchair fatigue life; in fact, in some cases, the modifications reduced wheelchair integrity. In addition, their increased expense considerably lowered their value in relation to the other types of wheelchairs. Altogether, little evidence was found to suggest that suspension manual wheelchairs provide advantages in terms of durability or value over non-suspension, folding-frame wheelchairs. The second section evaluated the ability of suspension manual wheelchairs to reduce the transmission of vibrations to the rider during various height curb descents and while traversing a level, uneven surface. In addition, impact force was measured during curb descent trials and used in the comparison. The results suggest that while the suspension manual wheelchairs provided significant (p = .0002) reduction in seat accelerations over both types of standard wheelchairs, this was due to the superiority of one wheelchair, the Sunrise Medical Quickie XTR. Furthermore, few significant improvements were found in terms of impact force and vibration dose value, which was calculated from seat accelerations measured during uneven surface testing. Overall the results indicate that suspension manual wheelchairs are not suited to suppress the shock vibrations or repeated low-level vibrations transmitted by curb descents and uneven terrain, respectively. The results of this research should be used to develop a more adequate wheelchair suspension system, and more importantly, should be considered by clinicians and wheelchair users when selecting a wheelchair for everyday use