Kinetic Patterns During Stair Ascent in Patients with Transtibial Amputations Using Three Different Prostheses

The purpose of the present research was to identify the kinetic strategy used by patients with unilateral transtibial amputations during stair ascent, and to determine the influence of three different prostheses on these kinetics. Five physically active transtibial amputees and five matched control subjects participated in this study. Amputee subjects were randomly assigned each of three prostheses, Flex-Foot, ReFlex VSP, and solid-ankle cushion-heel (SACH) foot. Subjects ascended a portable three-step staircase, with an isolated portion of the first step bolted to aforceplate. Three-dimensional marker positions were collected for the foot, leg, thigh, pelvis, and trunk, bilaterally on the amputee subjects and on the right side of the control subjects. Marker position data were combined with anthropometric data and forceplate data to perform the kinetic analysis. Net joint moment, power, and work values at the ankle, knee, and hip were determined for three trials for each subject. Peak moment, power, and work values were not different between the nonamputated side and the control subjects with the exception of the ankle, where the amputee subjects had greater power and work values. A comparison of the amputated and nonamputated sides showed a dominant- knee strategy on the nonamputated side and a dominant-hip strategy on the amputated side. The type of prosthesis was shown to make a difference at the hip, where greater work values were observed when subjects were wearing the SACH foot. The findings of this study may help to guide the rehabilitation of amputees and make a case for selecting an energy-storing prosthesis.