Abstract
Push-rim wheelchair propulsion frequently causes severe upper limb injuries in people relying on the wheelchair for ambulation. To address this problem, we developed a novel handle-based wheelchair propulsion method that follows a cyclic motion within ergonomic joint ranges of motion. The aim of this study was to measure hand propulsion forces, joint excursions and net joint torques for this novel propulsion device and to compare its performance against traditional push-rim wheelchair propulsion. We hypothesized that under similar conditions, joint excursions of this novel handle-based device will remain within their ergonomic range and that the effectiveness of the propulsion forces will be higher, leading to lower average propulsion forces compared to push-rim propulsion and reducing the risk of injury. Eight paraplegic subjects propelled the new device at two different loads on a custom-made wheelchair-based test rig. Video motion capture and force sensors were used to monitor shoulder and wrist joint kinematics and kinetics. Shoulder and wrist loads were calculated using a modified upper-extremity Wheelchair Propulsion Model available in OpenSim. The results show that with this novel propulsion device joint excursions are within their recommended ergonomic ranges, resulting in a reduced range of motion of up to 30% at the shoulder and up to 80% at the wrist, while average resultant peak forces were reduced by up to 20% compared to push-rim propulsion. Furthermore, the lower net torques at both the shoulder and wrist demonstrate the potential of this novel propulsion system to reduce the risk of upper-extremity injuries.
Highlights
THE wheelchair is an important aid for the mobility of physically disabled and injured persons, and the push-rim is the preferred mode of propulsion for a large percentage of wheelchair users even though it is associated with the least efficient pattern of propulsion [1]
The results show that with this novel propulsion device joint excursions are within their recommended ergonomic ranges, resulting in a reduced range of motion of up to 30% at the shoulder and up to 80% at the wrist, while average resultant peak forces were reduced by up to 20% compared to push-rim propulsion
The ergonomics literature indicates that push-rim propulsion (PRP) can lead to severe upper-limb injuries mainly at the shoulder and wrist joints, caused by the discontinuous, highly repetitive and complex upper-limb movements, which reportedly occur during PRP [3,4,5]
Summary
THE wheelchair is an important aid for the mobility of physically disabled and injured persons, and the push-rim is the preferred mode of propulsion for a large percentage of wheelchair users even though it is associated with the least efficient pattern of propulsion [1]. Koontz et al [8] simulated wheelchair propulsion over a level, smooth floor at two different speeds – 0.9m/s and 1.8m/s – and reported mean resultant peak propulsion forces of 58.9N ±11.6N at 0.9m/s and 94.3N ±26.4N at 1.8m/s. Koontz et al [9] analysed kinetics in 27 paraplegic subjects during PRP propulsion on a tile surface at a speed of 0.9m/s and found a peak shoulder abduction/adduction torque of 21.3Nm and shoulder rotation peak torques of 21.6Nm. Collinger et al [10] and Gil-Agudo et al [11] performed measurements under similar conditions and reported peak torques of 7.1Nm/15.3Nm (Collinger et al /Gil-Agudo et al ) and 5.8Nm/3.5Nm for shoulder ab-/adduction and shoulder rotation, respectively. PRP patterns are characterized by large variations between subjects and the results are altered by propulsion cadence [12]
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