Effect of foot and ankle immobilization on able-bodied gait as a model to increase understanding about bilateral transtibial amputee gait.

BACKGROUND: The anatomical foot-ankle complex facilitates advancement of the stance limb through foot rockers and late-stance power generation during walking, but this mechanism is altered for persons with bilateral transtibial amputation when using passive prostheses. OBJECTIVES: To study the effects of bilateral foot and ankle immobilization on able-bodied gait to serve as a model for understanding gait of persons with bilateral transtibial amputation and associated compensatory mechanisms. STUDY DESIGN: Comparative analysis. METHODS: Nine able-bodied persons walked at self-selected slow, normal, and fast speeds. They performed trials unaltered and when fitted with bilateral foot and ankle-immobilizing casts. Data from 10 individuals with bilateral transtibial amputation walking at self-selected fast speeds were used for qualitative comparison. RESULTS: The average speeds for the able-bodied fast speed cast and normal speed no-cast trials were similar and were compared with bilateral transtibial amputation data. The able-bodied cast condition data more closely matched bilateral transtibial amputation data than the no-cast data. Ankle range-of-motion and power generation at pre-swing in the cast condition were markedly decreased, while trunk lateral flexion and transverse rotation range-of-motion and peak hip power generation increased. CONCLUSION: Results suggest that the absence of active ankle range-of-motion and power generation contributes to the development of characteristic compensatory gait mechanisms displayed by persons with bilateral transtibial amputation. Clinical relevance This study helps to improve understanding of compensatory mechanisms resulting from reduced foot and ankle joint motion to inform lower limb prosthesis design and function for improving gait quality of individuals with bilateral transtibial amputation.