From Lab to Outdoors: The Effects of Terrain, Environment, Amputation level, and Prosthetic Knee Type on Gait

Abstract

While tremendous advances have been made in prosthesis technology, a greater understanding of amputee gait is needed, especially among amputees in developing countries. Field studies as well as prosthesis technology in developing countries are limited due to barriers associated with equipment and resources availability. Furthermore, individuals with lower limb amputation experience increased difficulty walking and a higher fall rate compared to non-amputees, which may be exacerbated by environment, terrain, or prosthesis componentry. Due to the importance of walking on various terrain for increased quality of life as well as the differences between prosthesis technology available in developing and developed countries, a better understanding of amputee gait on underdeveloped outdoor terrain is needed. We began to address these needs with three studies that explored factors that influenced and predicted amputee gait on realistic end-user outdoor terrain. First, we investigated the effects of environment (i.e. indoor laboratory or outdoor natural walking path), terrain, and amputation level on energy expenditure and dynamic stability while walking among lower limb amputees and non-amputees. We found that terrain and amputation level affected amputee energy expenditure and stability while environment and specific uneven terrain type had minimal effects. These results may guide future work investigating the effects of terrain in laboratory-based studies. Second, we investigated the ability to predict quantitative measures of amputee gait on outdoor underdeveloped terrain from laboratory-based measurements. We found individual participant characteristics and easily accessible measures of indoor gait were as or more effective at predicting energy expenditure and dynamic stability than gait measures requiring greater experimental and analytical resources. These results may offer a tool for researchers to assess performance among amputees in various settings without the need for expensive and technical equipment. Third, we examined the effect of a low-cost prosthetic knee joint on amputee gait. Specifically, we investigated the effects of on energy expenditure, gait stability, and perceptions of the low-cost prosthetic knee joint while walking on indoor and outdoor terrains. We found evidence that the low-cost knee increased energy expenditure and increased some characteristics of dynamic stability while decreased others. Furthermore, we also identified key insights among amputees about the performance of the low-cost prosthetic knee joint that could aid in future design modifications of the knee. Together, these studies help to clarify differences in walking performance between laboratory and outdoor terrains among lower limb amputees, help circumvent the challenges of obtaining quantitative gait measures during field studies in developing countries and may help guide the future design and use of low-cost prosthetic knee technology.