How Prosthetic Ankle Stiffness & Load Carriage Affect Metabolic Energy Expenditure During Walking

There are a number of activities of daily living that require people to carry additional loads. Walking with these loads can be a very challenging and demanding task for an individual with a transtibial (i.e. below-knee) amputation. For example, when carrying a 10-pound bag of groceries, some individuals with a transtibial amputation don’t feel confident enough with their prosthesis and choose to use a wheelchair instead. Therefore, the design of prostheses need to be improved to not restrict individuals with amputations in their daily activities. The purpose of this research is to conduct a biomechanics-based experiment to identify key prosthetic characteristics (such as mechanical stiffness) that influence an individual’s ability to walk efficiently while carrying additional loads. Participants will simulate amputation by wearing a prosthesis with an immobilizer boot attached. The experiment will consist of nine conditions, which will include three different prosthetic stiffness settings and three different load carrying conditions via a weighted vest. The results of this research have the potential to change how future prosthesis are designed and prescribed, to make individuals with transtibial amputations walk more efficiently during activities of daily living. If there is an interaction effect between stiffness and load carriage, then a powered prosthesis can be programmed to vary the stiffness when additional load is applied. In an unpowered prosthesis, a nonlinear spring that changes stiffness like how the human ankle changes during unloaded and loaded conditions may be used to decrease the metabolic cost for individuals with an amputation