A team of researchers set out to quantify how people who use transtibial prostheses maintain dynamic balance during 90-degree turns. The results of their study provide insight into training models that could help reduce the high incidence of turn-related falls in this population and may suggest ways to alter prosthetic function to promote balance control.
For the study, eight participants with transtibial amputations and eight age-, height-, and sex-matched non-amputee controls performed left and right 90-degree step turns at a self-selected speed. The primary outcomes were range of whole-body angular momentum and positive and negative contributions of six segment groups (head/trunk, pelvis, arms, and legs) to whole-body angular momentum during the continuation stride.
The participants with amputations had greater range of frontal- and sagittal-plane whole-body angular momentum when turning with the prosthesis on the inside compared to the controls. They also had a greater range of whole-body angular momentum in all planes of motion when turning with the prosthesis on the inside compared to outside of the turn. The contributions for the head/trunk and inside and outside legs differed between groups and turns, suggesting altered interactions between segment momenta to compensate for the reduced contribution of the amputated leg, according to the study’s authors.
The study, “The ins and outs of dynamic balance during 90-degree turns in people with a unilateral transtibial amputation,” was published in the Journal of Biomechanics.