Dynamic Balance Control (DBC) in lower leg amputee subjects; contribution of the regulatory activity of the prosthesis side

This was a study involving 6 transfemoral and 8 transtibial amputees, and they were being tested to determine the individual contribution of the ankle torques generated by both legs in balance control during dynamic conditions. One of the main goals in the rehabilitation of amputee patients is regaining balance control. Traditionally therapy for these patients is aimed at creating equal load in both limbs while both walking and standing, essentially getting the patient comfortable using their prosthesis.

The stiffness of the prosthetic ankle/foot can help an amputee create ankle torque, this is a mechanical property of the prosthesis which influences both the stance and biomechanics of the gait.

Dynamic balance contribution is defined as "a direct reflection of the generated ankle torque in reaction to (external) perturbations of the center of mass" which provides a way to distinguish between the contributions of the individual ankle joints to balance control. In regard to amputees the dynamic balance control reflects their use of the prosthetic ankle stiffness in achieving balance control.

It was found that the prosthesis contributes less to blance than to weight, whereas in a healthy person (someone without an amputation) a shift in weight is accompanied by a shift in their dynamic balance control. This lead to the conclusion that there is much more asymmetry in balance control than in the weight bearing in each limb. The fact that balance control is not that closely correlated with the weight bearing supports suggests that both balance control and weight bearing in the individual limbs both represent different aspects of postural control while standing with a prosthesis.

I chose this article for two reasons, while I was growing up I was always interested in prosthetic limbs, and it had never really occurred to me before that balance was substantial controlled through the lower leg, which in a lower limb amputee is absent, this made me curious as to how they maintained their balance. The second reason was that as my mom has aged her balance has gotten substantially worse, and I thought this article might provide interesting insight into balance control

 

http://www.sciencedirect.com/science/article/pii/S0268003311001896