title: Effect of a gravity-compensating orthosis on reaching after stroke: evaluation of the Therapy Assistant WREX.
abstract: METHODS
  Within-subjects repeated-measures design evaluating reaching with and without the Therapy Assistant Wilmington Robotic Exoskeleton (WREX).
  
  
  METHODS
  Laboratory.
  
  
  METHODS
  Stroke survivors (N=10) with chronic upper-extremity hemiparesis.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  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.
authors.affiliation: Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL 60611, USA.
authors.forename: Bridget T
authors.initials: BT
authors.lastname: Iwamuro
authors.forename: Erik G
authors.initials: EG
authors.lastname: Cruz
authors.forename: Lauri L
authors.initials: LL
authors.lastname: Connelly
authors.forename: Heidi C
authors.initials: HC
authors.lastname: Fischer
authors.forename: Derek G
authors.initials: DG
authors.lastname: Kamper
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D004576:Electromyography; D004867:Equipment Design; D005260:Female; D006112:Gravitation; D006801:Humans; D008297:Male; D008875:Middle Aged; D009989:Orthotic Devices; D010291:Paresis / Q000534:rehabilitation*; D000071939:Stroke Rehabilitation; D013813:Therapy, Computer-Assisted / Q000295:instrumentation*; D034941:Upper Extremity