Effects of unilateral robotic limb loading on gait characteristics in subjects with chronic stroke.
BACKGROUND
Hemiparesis after stroke often leads to impaired ankle motor control that impacts gait function. In recent studies, robotic devices have been developed to address this impairment. While capable of imparting forces to assist during training and gait, these devices add mass to the paretic leg which might encumber patients' gait pattern. The purpose of this study was to assess the effects of the added mass of one of these robots, the MIT's Anklebot, while unpowered, on gait of chronic stroke survivors during overground and treadmill walking.


METHODS
Nine chronic stroke survivors walked overground and on a treadmill with and without the anklebot mounted on the paretic leg. Gait parameters, interlimb symmetry, and joint kinematics were collected for the four conditions. Repeated-measures analysis of variance (ANOVA) tests were conducted to examine for possible differences across four conditions for the paretic and nonparetic leg.


RESULTS
The added inertia and friction of the unpowered anklebot had no statistically significant effect on spatio-temporal parameters of gait, including paretic and nonparetic step time and stance percentage, in both overground and treadmill conditions. Noteworthy, interlimb symmetry as characterized by relative stance duration was greater on the treadmill than overground regardless of loading conditions. The presence of the unpowered robot loading reduced the nonparetic knee peak flexion on the treadmill and paretic peak dorsiflexion overground (p < 0.05).


CONCLUSIONS
Our results suggest that for these subjects the added inertia and friction of this backdriveable robot did not significantly alter their gait pattern.
Khanna
Ira
I
Department Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
Roy
Anindo
A
Rodgers
Mary M
MM
Krebs
Hermano I
HI
Macko
Richard M
RM
Forrester
Larry W
LW
D000328:Adult; D000368:Aged; D000843:Ankle Joint / Q000503:physiopathology; D001696:Biomechanical Phenomena; D002908:Chronic Disease; D005260:Female; D005684:Gait / Q000502:physiology*; D020233:Gait Disorders, Neurologic / Q000503:physiopathology / Q000534:rehabilitation; D006621:Hip Joint / Q000503:physiopathology; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D007866:Leg / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012371:Robotics / Q000295:instrumentation*; D020521:Stroke / Q000503:physiopathology*; D000071939:Stroke Rehabilitation