A KINEMATIC AND KINETIC-ANALYSIS OF THE SIT-TO-STAND TRANSFER USING AN EJECTOR CHAIR - IMPLICATIONS FOR ELDERLY RHEUMATOID ARTHRITIC PATIENTS

Twelve elderly female rheumatoid arthritis patients (mean age = 65.5 /- 8.6 yr) were assessed rising from an instrumented Eser Ejector chai r under four conditions: high seat (540 mm), low seat (450 mm), with a nd without the ejector mechanism operating. Sagittal plane motion, gro und reaction forces, and vertical chair arm rest forces were recorded during each trial with the signals synchronised at initial subject hea d movement. When rising from a high seat, subjects displayed significa ntly (p < 0.05) greater time to seat off; greater trunk, knee and ankl e angles at seat off; increased ankle angular displacement; decreased knee angular displacement; and decreased total net and normalised arm rest forces compared to rising from a low seat. When rising using the ejector mechanism, time to seat off and trunk and knee angle at seat o ff significantly increased, whereas trunk and knee angular displacemen t, and total net and normalised arm rest forces significantly decrease d compared to rising unassisted. Regardless of seat height or ejector mechanism use, there were no significant differences in the peak, or t ime to peak horizontal velocity of the subjects' total body centre of mass, or net knee and ankle moments. It was concluded that increased s eat height and use of the ejector mechanism facilitated sit-to-stand t ransfers performed by elderly female rheumatoid arthritic patients. Ho wever, using the ejector chair may be preferred by these patients comp ared to merely raising seat height because it does not necessitate the use of a footstool, a possible obstacle contributing to falls. (C) 19 98 Elsevier Science Ltd. All rights reserved.