SEAT INTERFACE PRESSURES OF INDIVIDUALS WITH PARAPLEGIA - INFLUENCE OF DYNAMIC WHEELCHAIR LOCOMOTION COMPARED WITH STATIC SEATED MEASUREMENTS

Objective: To provide a comparison of the seat interface pressures bet ween static seating and dynamic seating during wheelchair locomotion o f individuals with paraplegia. Design: Repeated measures multivariate analysis of variance (MANOVA) comparing mio conditions: static seat an d dynamic seat interface pressures. Setting: University campus and cli nic. Participants: Fifteen participants, each of whom propelled a manu al wheelchair for at least 5 hours per week over the previous 6 months and functioned with a spinal cord injury/disability level of T1 or be low. Main Outcome Measures: Peak pressure (PP) and pressure time integ ral (PTI) as measured by the Novel Pliance System(TM), which consists of a flexible 32 x 32 capacitive sensor mat (each sensor 1.5cm(2)) int erfaced with a PC, was sampled at 10Hz. The participants were measured in their own wheelchair with a new Jay Active seat cushion. Results: The repeated measures MANOVA showed a difference in the PP and PTI bet ween the static and dynamic measurements (Wilk's = .00, p < .05). Foll ow-up dependent t tests yielded a difference in PP (t = 5.40, p < 0.02 5) and no difference in the PTI between static and dynamic conditions (t = 1.45, p > 0.025). The PP during static seating (mean = 16.2 +/- 5 .0kPa [121 +/- 37.5mmHg]) was less than during dynamic seat interface pressures during wheelchair locomotion (20.03 +/- 6.6kPa [152.3 +/- 49 .5mmHg]). PP varied by up to 42% during the wheelchair locomotion cycl e. The PTI was similar between static (30.1 +/- 9.3kPa [225.75 +/- 69m mHg]) and dynamic conditions (36.2 +/- 18.1kPa [271 +/- 135.7mmHg]). C onclusions: The results from this study are consistent with some of th e previous work on the nondisabled and a single case study, but with g reater external validity because of the nature of the sample chosen an d the methodology employed. PPs were greater during dynamic wheelchair locomotion compared with static seating interface pressures, with the peak varying up to 42% during the wheelchair locomotion cycle. The PT I indicates that the cumulative effect of the loading was comparable b etween conditions. The question that remains is whether this dynamic l oading, resulting in a change in PP throughout the cycle, has a signif icant effect on tissue health. (C) 1998 by the American Congress of Re habilitation Medicine and the American Academy of Physical Medicine an d Rehabilitation.