Gait initiation of persons with below-knee amputation: the characterization and comparison of force profiles.

The purpose of this study was to characterize gait initiation of persons with leg amputation and determine whether prosthetic alignment was a critical parameter in the initiation process. Gait initiation was chosen for study because of the difficult neuromuscular demands placed on the body in negotiating the transition from stance to ambulation. In this investigation, ground reaction force data were collected on seven persons with below-knee amputation. These subjects underwent a series of gait initiation trials while varying prosthetic alignment. An analysis of the data demonstrated key elements in the gait initiation process, including the motion of the center of gravity in preparation for steady-state walking. Significant asymmetries in the force profiles of the residual and nonamputated limbs were also found; gait initiation forces were consistently higher for the prosthetic limb and the timings of maxima and minima were indicative of an intact limb preference. Relatively small changes in prosthesis alignment proved not to have statistically significant effects on generalized force parameters. This result is consistent with the findings of other studies that gait initiation is a motor program with certain invariant characteristics.