Trainer variability during step training after spinal cord injury: Implications for robotic gait-training device design.

Robotic devices are being developed to automate repetitive aspects of walking retraining after neurological injuries, in part because they might improve the consistency and quality of training. However, it is unclear how inconsistent manual training actually is or whether stepping quality depends strongly on the trainers' manual skill. The objective of this study was to quantify trainer variability of manual skill during step training using body-weight support on a treadmill and assess factors of trainer skill. We attached a sensorized orthosis to one leg of each patient with spinal cord injury and measured the shank kinematics and forces exerted by different trainers during six training sessions. An expert trainer rated the trainers' skill level based on videotape recordings. Between-trainer force variability was substantial, about two times greater than within-trainer variability. Trainer skill rating correlated strongly with two gait features: better knee extension during stance and fewer episodes of toe dragging. Better knee extension correlated directly with larger knee horizontal assistance force, but better toe clearance did not correlate with larger ankle push-up force; rather, it correlated with better knee and hip extension. These results are useful to inform robotic gait-training design.

Quantification of therapists' manual assistance on the leg during treadmill gait training with partial body-weight support after spinal cord injury.

We are studying the forces applied by therapists when assisting on the legs of patients with spinal cord injury (SCI) during body-weight supported treadmill training (BWSTT). This paper presents results from three experiments with three patients and six different therapists. We attached a sensorized orthosis to one of the legs of the patients and measured the forces exerted by the therapists when assisting on that leg through the orthosis. We also measured the kinematics of the shank. The hips and opposite leg were assisted by two other therapists as usual. We found a high repeatability across steps for the forces applied by each therapist. Better-skilled therapists elicited significantly better leg extension in stance phase by exerting significantly larger horizontal forces on the knee during stance. Better-skilled therapists also elicited better toe clearance during initial-to-mid swing, with fewer or no episodes of toe dragging. This better toe clearance was not generally correlated with larger therapist push-up forces at the ankle. We did find, however, that better toe clearance in swing was correlated with better extension of the same leg in stance, suggesting that a normative leg extension in stance contributed to better muscle activity of the same leg in swing. These results provide insight into therapist-assisted gait training, which may be useful for optimizing robotic gait-training devices.

Locomotor training using body weight support on a treadmill improves mobility in persons with multiple sclerosis: a pilot study.

RATIONALE: The purpose of this protocol was to investigate the potential benefits and tolerability of locomotor training using body weight support on a treadmill (LTBWST) in persons with multiple sclerosis (MS). METHODS: Four persons with primarily spinal cord MS and severely impaired ambulation (Expanded Disability Status Scale score 7.0-7.5) were enrolled in LTBWST. Subjects completed an average of 40 training sessions over several months. RESULTS: Subjects showed improvement in muscle strength, spasticity, endurance, balance, walking speed, and quality of life at the end of the training sessions, and could tolerate training without fatigue or other adverse effects. CONCLUSIONS: LTBWST is well tolerated by persons with MS and may produce improvements in parameters related to functional mobility.