Researchers from the University of Bradford, Yorkshire, England, conducted a study to examine gait adaptations involving obstacle crossing in individuals with lower-limb amputations as compared to able-bodied subjects with the aim of identifying underlying gait characteristics between the two groups. They found that when negotiating obstacles, those with lower-limb amputations reduced their step length to control the landing and loading of the prosthesis after crossing an obstacle. The step length reduction strategies included reducing the approach velocity, the foot placement distance before and after the obstacle, the foot clearance over it, and the lead-limb knee flexion during the step following crossing.
Eight people with unilateral transtibial amputations and 12 people without amputations completed adaptive gait trials by negotiating obstacles of various heights. The individuals with amputations were asked to lead with their prosthetic limb.
Getting closer to the obstacle before crossing it appeared to ensure that the heel of the prosthetic foot, the leading foot, passed over the obstacle prior to the foot being lowered to the ground. Despite this heel clearance strategy, the lead foot was positioned closer to the obstacle following crossing, creating a limb/foot angle and orientation at the instant of landing that minimized loads on the residual limb, which the researchers state was also evidenced by the reduced lead-limb knee flexion during the step following crossing. These changes in foot placement meant the foot was in a different part of swing at the point of crossing and demonstrates why foot clearance is considerably reduced in individuals with lower-limb amputations.
The results of the study were published in the August issue of the Journal of Neuroengineering and Rehabilitation.