Factors that influence changes in wheelchair cushion performance over time.

Wheelchair cushions can be used for many hours every day. Like all devices, cushions degrade over time, losing the ability to provide adequate support. Little is known about the changes that cushions undergo after typical everyday use. This project was designed to monitor cushion performance over time with the objective to identify the most important factors that predict cushion degradation. Wheelchair users and their cushions were evaluated multiple times. Information was collected about participants' posture and activities, their cushions, and use of their cushions. Cushion performance was determined by measuring interface pressure using a buttock model. Data analysis proceeded in two steps. First, principal component analysis was run to reduce the number of variables. Second, multiple regression determined which variables influenced the interface pressure performance variables. Results indicated that user characteristics and the manner in which the cushion is used have a greater influence on cushion performance than the chronological age of the cushion. This result can be useful to clinicians who should query users about cushion use when investigating the need to replace a cushion. Finally, this information is applicable to policies that govern cushion replacement and indicted that wear on a cushion is not equivocal across users.