Comparison of an ankle-foot-orthosis and neuroprosthesis during level and non-level walking for individuals post-stroke
Date of Award
Master of Science (MS)
Silver-Thorn, Barbara M.
Harris, Gerald F.
Stoeckmann, Tina M.
This study used gait analysis to compare the efficacy of the two foot drop treatments (ankle-foot-orthosis and neuroprosthesis) and to contrast the stimulation control of the two different neuroprosthesis sensors during level and non-level ambulation of post-stroke individuals.
Eight subjects completed two gait analysis sessions, once while using a study-provided articulated AFO and the other while using a WalkAide. After four weeks of acclimation to the device, each subject performed two minute walking trials on a level, inclined and declined treadmill. Kinematic and heart rate data were collected for all sessions. Plantar pressure and WalkAide tilt, heel loading, and stimulation timing data were collected during WalkAide sessions. Temporal parameters, kinematic gait asymmetry (GA), toe clearance, as well as WalkAide stimulation reliability (StR) and stimulation timing, were computed from Vicon and WalkAide data. Wilcoxon signed rank and Friedman tests were conducted to identify significant differences between treatments and amongst treadmill orientations, respectively.
Significantly greater minimum and mean ankle GA during initial swing was observed during AFO versus WalkAide ambulation for all treadmill orientations. Further analysis revealed that the ankle range of motion between affected and unaffected limbs was significantly different for the AFO, but not the WalkAide. Review of functional assessments indicated that these differences in ankle GA during initial swing may be attributed to the rigidity of the AFO, not functional gains with the WalkAide.
Comparison of the two sensor control options yielded mixed results. More optimal StR values were observed during heel sensor-based stimulation by 25% of the post-stroke subjects. Changes in StI on non-level surfaces occurred with the tilt sensor, but not the heel sensor. However, progressively delayed StI timing from declined to inclined walking with the tilt sensor may result in increased ankle plantar flexion during PS, providing beneficial during inclined ambulation.
Improved kinematic gait symmetry and StI changes on inclined surfaces with the WalkAide may be beneficial for community stroke ambulators on inclined surfaces; however, the lower StR and increased stimulating timing variability raise concerns about safety of the WalkAide while using tilt sensor controlled stimulation. The WalkAide heel sensor may provide a consistent, safer substitute.