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Logo for the Journal of Rehab R&D
Vol. 39 No. 6, November/December 2002

Summaries of
Scientific/Technical ARTICLES

Kinetic and physiological analysis of the GAMEWheels system
Thomas J. O’Connor, PhD; Shirley G. Fitzgerald, PhD; Rory A. Cooper, PhD; Tricia A. Thorman, MOT;
Michael L. Boninger, MD

Purpose of the Work. This study investigated whether the GAMEWheels exercise system was harmful to the upper arms of individuals who use wheelchairs. GAMEWheels is an interface between a roller system and a computer, enabling the user to play a game while exercising. Subjects and Procedures. Ten manual wheelchair users exercised on the GAMEWheels system with and without play of a video game. Data collected included forces to the arm as result propulsion as well as information regarding oxygen consumption and heart rate during each trial. Results. Results indicated that there were no differences in the forces between the two trials (playing the game and not playing the game) during exercise sessions. Significant differences were found between the two exercise sessions with respect to heart rate and oxygen consumption, with increased values seen when game play was occurring during exercise. Relevance to the Veteran Population. Exercise is important to maintaining the health and well-being for all individuals. For individuals who use wheelchairs, opportunities to exercise are limited and are usually not highly motivating experiences. GAMEWheels provides a safe exercise option to veterans who use wheelchairs.

Shirley G. Fitzgerald, PhD
Shoulder kinematics and kinetics during two speeds of wheelchair propulsion
Alicia M. Koontz, PhD, ATP; Rory A. Cooper, PhD; Michael L. Boninger, MD; Aaron L. Souza, MS;
Brian T. Fay, PhD

Purpose of the Work. Daily wheelchair propulsion has been associated with the development of repetitive strain injuries at the shoulder. Limited data have been published on the shoulder because of the complexity of the joint and limitations in instrumentation to measure arm motion and strain. This study determined the loads acting on the shoulders and their corresponding movement patterns during wheelchair propulsion to understand possible precursors to injury. Subjects and Procedures. Twenty-seven adults with paraplegia volunteered to participate in this study. The subjects’ own manual wheelchairs were instrumented with wheels that measured applied hand force and torque. Their arms were prepared with markers for tracking their arm movements. Subjects propelled on a roller system at two constant speeds (2 and 4 mi/h) while data were collected. A mathematical model was applied to calculate the loads and motion of the shoulder joint. Results. The shoulders moved through a greater range of motion, and loads were calculated that were nearly two times greater at the fast speed compared to the slow speed. Maximum loads tended to occur when the shoulder joint was in a position commonly associated with repetitive-type injuries involving the rotator cuff. Relevance to the Veteran Population. Certain shoulder positions combined with large loads acting on the shoulder during wheelchair propulsion may predispose veterans who use manual wheelchairs to shoulder pain and injury. Propelling at slow speeds (<2 mi/h) minimizes shoulder strain. This study may reveal new interventions and training strategies for preventing shoulder problems.

Alicia M. Koontz, PhD, ATP
Rate of isometric knee extension strength development and walking speed after stroke
Patricia S. Pohl, PhD; Pamela Duncan, PhD;
Subashan Perera, PhD; Jason Long, MS; Wen Liu, PhD; Jinshi Zhou, PhD; Steven A. Kautz, PhD

Purpose of the Work. This study examined the relationship between walking speed after stroke and two measures of isometric strength, the rate of torque development, and peak torque. Subjects and Procedures. The study included 83 adults poststroke, 44 males and 39 females between the ages of 50 and 90, who participated in the study. Walking speed was measured over 10 m. Knee extension strength was tested for the affected and less-affected limbs. Strength data from each limb were analyzed separately. Results. No more than 12% of the variance in walking speed was explained by age, gender, and the rate of torque development and peak torque. However, removing the rate of torque development significantly decreased the amount of variance explained. This was not true for peak torque. Relevance to the Veteran Population. After stroke, the rate of knee extension strength development may be more important than the maximum knee extension strength for walking speed.

Patricia S. Pohl, PhD
Consumer perspectives on mobility: Implications for neuroprosthesis design
Denise L. Brown-Triolo, MS, CRC;
Mary Joan Roach, PhD;
Kristine Nelson, MEd, CRC; Ronald J. Triolo, PhD

Purpose of the Work. This study investigated the viewpoint of persons with spinal cord injuries (SCIs) regarding perspectives of mobility to aid in the design of devices for enhanced mobility. Subjects and Procedures. Telephone interviews were conducted with 94 individuals with paraplegia. Respondents were asked to list by priority their desire to stand, walk, climb stairs, or transfer. Respondents were also asked to identify the acceptable qualities of activities and to assess their willingness to experience risks to attain them. Results. Top priorities were walking and then standing. Respondents indicated that the acceptable quality of new mobility activities did not have to be the same as premorbid function. However, those with more to gain were more willing to take risks to achieve improvement in walking and standing functions. Relevance to the Veteran Population. The results suggest that resistance to attaining any mobility intervention may have more to do with the time, energy, and risks than they do with the outcome. These results will allow researchers and clinicians to include the needs and desires of individuals with SCI in the development of assistive devices for mobility, such as neuroprostheses for standing and walking employing functional electrical stimulation.

Denise L. Brown-Triolo, MS, CRC
Electrode fracture rates and occurrences of infection and granuloma associated with percutaneous
intramuscular electrodes in upper-limb functional electrical stimulation applications
Jayme S. Knutson, MS; Gregory G. Naples, MS;
P. Hunter Peckham, PhD; Michael W. Keith, MD

Purpose of the Work. This work evaluated the reliability and safety of percutaneous intramuscular electrodes used in the upper limb. Subjects and Procedures. We reviewed data retrospectively on 858 electrodes implanted in the upper limbs of 62 subjects participating in research studies between 1978 and 1998. We assessed the frequency of electrode fracture and occurrences of infection and granuloma associated with the electrodes. The probability of electrode fracture as a function of the time an electrode remains implanted was calculated, delineating between fractures occurring before and during electrode extraction. In addition, the number and severity of incidents of infection and granuloma experienced were assessed. Results. The survival rate for a single electrode that has been in the body less than 6 months is greater than 78%. Electrode fracture was more likely to occur during extraction than before extraction. There were 23 occurrences of infection or granuloma experienced by 16% of the subjects. Less than 25% of these incidents were associated with fragmented electrodes. All the incidents were resolved with administering antibiotics, cleaning the implant site, removing electrodes, cauterizing with silver nitrate, or excising electrodes or granulomas. Relevance to the Veteran Population. Percutaneous electrodes provide a safe and effective minimally invasive technique for restoring motor function after paralysis of the central nervous system.

Jayme S. Knutson, MS
A multistage field test of wheelchair users for evaluation of fitness and prediction of peak oxygen consumption
Marc Vanderthommen, PhD; Marc Francaux, PhD;
Cédrik Colinet, BS; Cédric Lehance, BS;
Claude Lhermerout, PhD; Jean-Michel Crielaard, PhD; Daniel Theisen, PhD

Purpose of the Work. This study was conducted to develop an incremental multistage field test (MFT) for wheelchair users for the evaluation of physical fitness and peak oxygen consumption. Subjects and Procedures. Thirty-seven participants wheeled around an octagonal course (15 m × 15 m), increasing their velocity every minute until exhaustion. Velocity and metabolic parameters were recorded. Results. The average MFT score was 9.17 ± 5.81 exercise stages, peak oxygen consumption was 25.2±5.9 mL/min/kg, and peak heart rate was 172 ± 26 b/min. Peak oxygen consumption could be predicted moderately well by the MFT score, which was itself related to propulsion efficacy, wheelchair adjustments, and fitness. Relevance to the Veteran Population. The MFT is a reliable and easily applicable field test that evaluates overall wheelchair mobility and cardiorespiratory fitness of the wheelchair user.

Marc Vanderthommen, PhD
Interface pressures during ambulation usingsuction and vacuum-assisted prosthetic sockets
Tracy L. Beil, MS; Glenn M. Street, PhD;
Steven J. Covey, PhD, PE

Purpose of the Work. A vacuum-assisted socket has previously been shown to eliminate the daily limb volume loss that occurs when amputees use a normal total surface weight-bearing suction socket. This study determined how this new socket prevents the volume loss. Subjects and Procedures. Sensors measured compressive and suction pressures on the residual limbs of nine unilateral, transtibial amputees as they walked in each of the socket types. Results. The vacuum-assisted socket tends to drive less fluid out of the limb during stance (less compression) and draws more fluid in during swing (greater suction). These changes shift the fluid balance from a net loss to maintenance or gain. Relevance to the Veteran Population. A well-fitted socket is of the utmost importance for an amputee. This paper lends insight as to why the vacuum-assisted socket prevents the daily limb volume loss that can cause loss of proper fit.

Tracy L Beil, MS
Shooting mechanics related to player classification and free throw success in wheelchair basketball
Laurie A. Malone, PhD; Pierre L. Gervais, PhD;
Robert D. Steadward, PhD

Purpose of the Work. This study determined what factors are associated with successful free throw shooting in wheelchair basketball and examined the relationship between shooting mechanics and player classification. Procedures. Free throws were recorded during a men’s wheelchair basketball competition with the use of methods for three-dimensional video data collection. Joint angular motions of the shoulder, elbow, and wrist were calculated, as were parameters of ball release. Results. Significant differences were observed in free throw shooting between wheelchair basketball classes. Players in Classes 1 and 2 tended to release the ball from a lower height, with greater velocity and release angle. They also demonstrated a smaller shoulder flexion angle at release and a greater maximum velocity at the shoulder and elbow. Relevance to the Veteran Population. Preliminary information has been provided regarding the proper shooting mechanics for successful free throw shooting in wheelchair basketball.

Laurie A. Malone, PhD