Design and evaluation of a knee and ankle joint for the Cloud Walker: a novel passive gait orthosis

Abstract

Spinal cord injury(SCI) is a life-altering event that often leads to wheelchair confinement and a lifetime of secondary health complications. Gait orthoses aim to restore mobility and improve the quality of life for these individuals. However, they are often rejected due to the high energy expenditure required by the individual. This project focuses on the Cloud Walker, a novice reciprocating gait orthosis aiming to make a difference. This project aims to decrease the energy expenditure required to walk with the Cloud Walker, making it more likely to be used by individuals with SCI. It was hypothesized that by changing the locked ankle and knee joint of the original Cloud Walker with a passive knee joint and a stance control knee joint, the energy expenditure would go down and the self-selected speed would go up. Two randomized cross-over experiments validated the modified Cloud Walker. Participants wore both the original and the new orthoses while their metabolic values were being monitored. The results showed a 16.9% decrease in oxygen uptake, 7.1% lower heart rate, 16.5% lower energy consumption per hour, and 17.3% fewer calories burned with the new orthosis. Specifically, the knee joint alone accounted for a 13.0% decrease in oxygen uptake, 5.3% lower heart rate, 13.03% lower energy uptake, and 16.7% reduction in calorie expenditure. The self-selected walking speed increased by 30%, however this was not statistically significant. Overall the new version of the Cloud Walker showed to be a significant improvement to the original and is a step closer to helping people with spinal cord injury.