SWING-THROUGH GAIT WITH FREE-KNEES PRODUCED BY SURFACE FUNCTIONAL ELECTRICAL-STIMULATION

The swing-through gait is often the gait of choice for those crutch wa lkers who can perform it. However, a practical (sufficiently low energ y and sufficiently fast) gait is usually not achievable by paraplegic individuals with thoracic lesions. Functional electrical stimulation ( FES) was used to assist three spinal cord injured (SCI) subjects with complete thoracic lesions at T11, T11 and T6 to ambulate with a swing- through gait patten. Eight channels of surface stimulation were used t o bilaterally stimulate knee extensors, knee flexors, hip extensors an d hip flexors. The stimulation sequence was controlled by a computer t hat implemented a finite-state, rule-based control strategy according to sensor inputs. Over a long, level walkway, the T11 subjects average d 0.40 m/s and 0.38 m/s for distances of 56 m and 51 m; the T6 subject averaged 0.30 m/s for 43 m. Using a motion analysis system, the gait patterns of two of the subjects were compared to those of a trained, n on-impaired subject. The SCI subjects spent more time in both double s upport phases (when both crutches and both feet contact the floor) tha n did the non-impaired subject, leading to a loss of momentum and henc e a slower and less efficient gait. In conclusion, an FES assisted swi ng-through gait is shown to be a potentially useful mode of FES gait.