Archives of Physical Medicine and Rehabilitation
Volume 89, Issue 11 , Pages 2121-2128, November 2008

Effect of a Gravity-Compensating Orthosis on Reaching After Stroke: Evaluation of the Therapy Assistant WREX

  • Bridget T. Iwamuro, BS

      Affiliations

    • Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL
    • ,
  • Erik G. Cruz, MS

      Affiliations

    • Beghou Consulting, Evanston, IL
    • ,
  • Lauri L. Connelly, MS, OTR/L

      Affiliations

    • Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL
    • ,
  • Heidi C. Fischer, MS, OTR/L

      Affiliations

    • Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL
    • Corresponding Author InformationCorrespondence to Heidi C. Fischer, MS, OTR/L, Rehabilitation Institute of Chicago, 345 E Superior St, Ste 1406, Chicago, IL 60611
    • ,
  • Derek G. Kamper, PhD

      Affiliations

    • Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL
    • Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL

Abstract 

Iwamuro BT, Cruz EG, Connelly LL, Fischer HC, Kamper DG. Effect of a gravity-compensating orthosis on reaching after stroke: evaluation of the Therapy Assistant WREX.

Objective

To evaluate the effectiveness of an upper-extremity orthosis to improve the reaching workspace of stroke survivors.

Design

Within-subjects repeated-measures design evaluating reaching with and without the Therapy Assistant Wilmington Robotic Exoskeleton (WREX).

Setting

Laboratory.

Participants

Stroke survivors (N=10) with chronic upper-extremity hemiparesis.

Interventions

Not applicable.

Main Outcome Measures

Arm movement kinematics (Optotrak Certus motion detection system), muscle activity for biceps, triceps, anterior deltoid, and brachioradialis muscles (bipolar surface electromyography).

Results

Significant improvements of reaching distance occurred for all subjects across all targets (P<.001) when using the Therapy Assistant WREX. While the self-selected peak speed of hand movement during the reach decreased significantly with the Therapy Assistant WREX (P<.001), use of the Therapy Assistant WREX led to improved quality of movement as signified by a decrease in jerk (P<.001) and a shift in the timing of the peak speed to an earlier point in the movement (P<.001). Electromyographic muscle activity analysis showed that use of the Therapy Assistant WREX led to a reduction in biceps activity across all targets during the reach (P<.05), in conjunction with a marginally significant reduction in activity of the anterior deltoid (P<.055). No changes were observed in triceps (P=.47) or brachioradialis activity (P=.28).

Conclusions

By reducing requirements for shoulder activation, the Therapy Assistant WREX improved reaching performance among stroke survivors compared with free reaching, thereby potentially facilitating practice of functional tasks.

Key Words: Orthotic devices, Rehabilitation, Stroke, Upper extremity

List of Abbreviations: ANOVA, analysis of variance, DOF, degrees of freedom, EMG, electromyography, jerk, rate of change of acceleration, WREX, Wilmington Robotic Exoskeleton

 

 Supported by the National Institute on Disability and Rehabilitation Research, Rehabilitation Research and Training Center for Stroke (grant no. H133B031127), and by the Coleman Foundation.

 No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated.

 Reprints are not available from the author.

PII: S0003-9993(08)00794-6

doi:10.1016/j.apmr.2008.04.022

Archives of Physical Medicine and Rehabilitation
Volume 89, Issue 11 , Pages 2121-2128, November 2008

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