Wrist biomechanics during two speeds of wheelchair propulsion: an analysis using a local coordinate system.
ABSTRACT To describe motion, forces, and moments occurring at the wrist in anatomic terms during wheelchair propulsion; to obtain variables that characterize wrist function during propulsion and are statistically stable; and to determine how these variables change with speed.
Convenience sample of Paralympic athletes (n = 6) who use manual wheelchairs for mobility and have unimpaired arm function.
Subjects propelled a standard wheelchair on a dynamometer at 1.3m/sec and 2.2m/sec. Biomechanical data were obtained using a force and moment sensing pushrim and a motion analysis system.
Maximum angles, forces, and moments in a local, wrist coordinate system. Each variable was evaluated for stability using Cronbach's alpha. Measures found to be stable (infinity > .8) at each speed were then compared to look for differences associated with speed.
The following measures were stable at both speeds: maximum wrist flexion, ulnar deviation, and radial deviation angles, peak moments acting to cause wrist flexion, extension, and ulnar deviation, peak shear forces acting between the radial and ulnar styloids, and peak axial force acting at the wrist. Of these measures, the following measures differed (p < .05) between speeds (+/-SD): maximum radial deviation (1.3m/sec, 25.1 degrees +/- 9.0; 2.2m/sec, 21.4 degrees +/- 6.9), peak flexion moment (1.3m/ sec, 3.4N.m +/- 3.0; 2.2m/sec, 5.2N.m +/- 3.7), peak extension moment (1.3m/sec, 10.4N.m +/- 4.8; 2.2m/sec, 13.6N.m +/- 5.1), peak shear acting from the ulnar styloid to the radial styloid (1.3m/sec, 2.3N +/- 2.7, 2.2m/sec, 8.3N +/- 7.5) and maximum axial force (1.3m/sec, 50.9N +/- 18.2; 2.2m/sec, 65.9N +/- 27.6).
This study found stable parameters that characterize wrist biomechanics during wheelchair propulsion and varied with speed. Ultimately these parameters may provide insight into the cause and prevention of wrist injuries in manual wheelchair users.
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ABSTRACT: Manual wheelchair users commonly experience pain in their hands and wrists associated with the repetitive stress of propulsion. The objective of this research was to examine the effect of an ergonomic wheelchair handrim as an intervention designed to reduce pain in the hands and wrists and improve functional outcomes for manual wheelchair users. Three studies were conducted to achieve this objective. In the first study, 10 individuals with paraplegia underwent a biomechanical analysis before and after a 2-week practice period with a Natural-Fit (NF) prototype ergonomic handrim. The biomechanical results showed that grip moments were reduced with the NF handrim prototype as compared with the subjects' current handrim (p < .1). Other biomechanical findings were mixed. In the second study, 46 manual wheelchair users who replaced their standard handrim with the commercially available NF handrim completed a questionnaire of retrospective measures of symptom severity. Average duration of use of the NF was 6 months. When asked to compare propelling with the NF to propelling with their prior handrims, 85% of respondents reported less pain in their hands and 80% reported less pain in their wrists. The third study was a replication and extension of Study 2: 82 manual wheelchair users who replaced their standard handrim with the NF completed retrospective symptom severity and functional status scales after using the NF for an average of 9 months. Results again confirmed that using the NF led to a reduction in the severity of symptoms and to improved functional outcomes.Assistive technology: the official journal of RESNA 02/2006; 18(2):123-43; quiz 145. DOI:10.1080/10400435.2006.10131912 · 0.51 Impact Factor
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ABSTRACT: Hand rim wheelchair propulsion is inefficient and physically straining. To evaluate the possibly advantageous role in this respect of three different prototype hand rim configurations (a rubber foam-coated cylindrical (II) hand rim and two profiled rubber foam-coated hand rims (wide and narrow: III, IV)), a group of 10 unimpaired subjects conducted four submaximal discontinuous wheelchair exercise tests on a computer-controlled wheelchair ergometer, thus allowing a comparison with a standard hand rim (chromium-plated round hand rim (I)). Apart from physiological measures (oxygen uptake, heart rate (HR), ventilation, mechanical efficiency (ME)), a subjective score for the rating of each of the hand rims was determined, as well as characteristics of the force application in the propulsion phase during each test condition. Timing parameters of the push and recovery phase were determined. Each exercise test was conducted with one of the four hand rim configurations in a counter-balanced order. Analysis of variance with repeated measures (hand rim configuration, power output) revealed no significant effects (P>0.05) on any of the physiological parameters and force application characteristics for the main factor 'hand rim configuration'. Only the subjective score (scale 0-10) for rating of the hand rims proved significantly different between the round rubber (7.5+/-0.53) coated hand rim-receiving the highest score-versus the narrow rubber-coated flat profiled hand rim (5.5+/-1.72). In this subject group and under the selected tasks and submaximal conditions of wheelchair propulsion, the studied hand rim configurations did not introduce critical shifts in the technique of (de-)coupling and power production in the push phase. As a consequence, no systematic shifts in ME are found among the different hand rim configurations. It is suggested that the biological constraints of the task overrule the possible effects of small design variations of the different hand rim configurations within the studied subject group and under the limited test conditions. The hand rim design characteristics may however be much more critical in (1) experienced wheelchair users, (2) especially those subjects with a limited hand-arm and/or trunk function and/or (3) under much more extreme conditions of daily wheelchair ambulation (i.e. turning, stopping/starting, negotiating a slope) or during peak performance. These issues clearly require continued future research. As such, the current results can be viewed as preliminary results only.Medical Engineering & Physics 11/2003; 25(9):765-74. DOI:10.1016/S1350-4533(03)00102-4 · 1.84 Impact Factor
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ABSTRACT: To assess the mechanical load on the glenohumeral joint and on shoulder muscles during wheelchair propulsion at everyday intensities. Model simulations based on experimental input dataBackground. Virtually nothing is known about the mechanical load on the upper extremity during wheelchair propulsion. Hand rim wheelchair propulsion is a significant risk factor for shoulder pain and injury among wheelchair users. A musculoskeletal model of the upper extremity during wheelchair propulsion will quantify the stresses placed on anatomic structures and may provide insight into the source of symptoms and injuries. Three experienced wheelchair users underwent wheelchair exercise tests at combinations of two load levels (10 and 20 W) and two velocities (0.83 and 1.39m.s(-1)) during which input data were collected for a musculoskeletal model of the upper extremity. The model was then used for the estimation of the glenohumeral contact force, as well as individual muscle forces. Peak glenohumeral contact forces were between 800 and 1400 N (100-165% body weight) and differed significantly between load levels. Averaged over the push phase, these forces were 500-850 N. In absolute terms the m. deltoideus and rotator cuff muscles were highly active (>100N). In relative terms the load on the m. supraspinatus was high, with peak values of over 50% of its maximum attainable force. Low intensity wheelchair propulsion does not appear to lead to high contact forces. The muscle forces in the rotator cuff and especially in the m. supraspinatus are high. This might indicate a risk for muscle damage and the subsequent development of shoulder complaints, such as rotator cuff tears. Within the wheelchair user population, there is a high prevalence of upper extremity complaints. Not much is known about the causes of those complaints. Wheelchair propulsion is likely to be a major risk factor. If the (nature of this) mechanical load can be identified, specific exercise programs and/or design changes can be better tuned to prevent overuse injuries.Clinical Biomechanics 03/2002; 17(3):211-8. DOI:10.1016/S0268-0033(02)00008-6 · 1.88 Impact Factor