Usability evaluation of three unilateral - Propelled wheelchairs for hemiplegic patients

Most hemiplegic patients use the unaffected arm and leg to propel wheelchair. The asymmetrical forces may cause the wheelchair to stray toward the affected side on level surface, and even cause danger on a slope. Although a variety of designs from mechanical approach have been developed to improve propulsion efficiency and reduce injuries, such as hand-lever drive and crank propulsion, most of them were just designed for users having healthy upper limbs. The purpose of this study was to evaluate the usability and the physiological responses of each of the two new wheelchairs comparing with a commercial two-handrim propelled wheelchair at a rehabilitation center. Two newly designed wheelchairs (ankle-propelled wheelchair (APW), knee-propelled wheelchair (KPW)) were recruited and compared with a commercial two-handrim propelled wheelchair (TPW). 15 stroke patients were recruited from the rehabilitation center of Chung Shan Medical University, Taichung, Taiwan. Subjects propelled the three wheelchairs along an oval-shaped pathway and videotape was made during test for analysis. The parameters, including total propelling time, deviation frequencies, deviation percentage, physiological cost index (PCI), maximum VO2 (VO2max), and rating of perceived exertion (RPE) were measured and compared among the three types of wheelchair. The results show that KPW had the best results in terms of performance evaluation among the three wheelchairs no matter in controllability, cardiopulmonary responses, or RPE. However, the gear ratio of force transmitting system of KPW was fixed, and some patients felt that the propulsion was heavy when starting KPW. It was more suitable and comfortable for hemiplegic patients to use KPW than to propel TPW and APW. If the adjustment of KPW were properly improved, it would be a comfortable device for movement for hemiplegic patients.