Pushrim-activated power-assist wheelchairs: elegance in motion.

Manual wheelchair propulsion has been linked to a variety of upper limb disorders, including rotator cuff tendonitis, lateral epicondylitis, cubital tunnel and carpal tunnel neuropathies, fibrocartilage metaplasia, and calcific tendonitis. However, manual wheeling also provides aerobic exercise. The benefits of exercise are well known and include promotion of cardiovascular fitness, reduction of hypertension, improved glycemic control, improved lipid profiles, reduction of anxiety, and an improved sense of well-being. Animal studies suggest that exercise can induce expression of genes associated with neural plasticity, long-term potentiation, neurogenesis, and resistance to injury such as that encoding brainderived neurotrophic factor. Manual propulsion has also been associated with positive self-esteem and positive body image. Thus, rehabilitation professionals should promote manual wheeling whenever possible and practical. Pushrim-activated power-assist wheelchairs (PAPAWs) decrease the biomechanical and physiologic stress associated with self-propulsion while preserving the opportunity to exercise while wheeling. Torque applied to the pushrims activates small, lightweight motors. These in turn provide brief bursts of power to drive the wheels, resulting in augmented wheeling. To keep a PAPAW moving, users repeatedly stroke the pushrim as they would if they were propelling conventional manual wheelchairs. PAPAWs are an intermediate alternative between conventional power and manual wheelchairs. Like power chairs, PAPAWs allow access to multiple environments (carpets, steep inclines, grass, etc.) that are often inaccessible to manual wheeling. However, like manual wheelchairs, PAPAWs are relatively lightweight (weighing as little as 57 lbs) and still provide an exercise challenge. Limitations to wide acceptance of PAPAWs include cost, greater difficulty in loading and unloading in motor vehicles compared with manual chairs, and lack of awareness among users and practitioners. Three power-assist options are currently available in the United States: (1) The e.motion M12, manufactured by Alber of Albstadt, Germany, and marketed in the United States by Frank Mobility Systems of Oakdale, PA; (2) the JW II, manufactured by Yamaha, Shizuoka, Japan, available in the United States as the Quickie Xtender from Sunrise Medical, Longmont, CO; and (3) the iGlide, manufactured by Independence Technology, Warren, NJ (Fig. 1) Significant differences exist between each of these models. These differences include the mechanisms and algorithms employed to link pushrim input to motor output, weight of each PAPAW, programmability, ease of wheel removal, number of available configurations, battery placement, ability to traverse challenging environments, downhill safety, motor noise, and others. As PAPAWs evolve, they are likely to become lighter, more powerful, and more widely and easily programmable. Familiarity with PAPAWs will aid in optimal wheelchair prescription.