A methodology for studying the effects of various types of prosthetic feeton the biomechanics of trans-femoral amputee gait

This paper reports on a methodology developed for studying the effects of v arious types of prosthetic feet on the gait of trans-femoral amputees. It i s shown that an analysis in three planes of motion of not only the prosthet ic, but also the sound limb provides important information on the performan ce of prosthetic feet. Two male trans-femoral amputees were tested with fou r different prosthetic feet; the Springlite II, Carbon Copy III, Seattle Li ghtFoot and the Multiflex foot. A detailed analysis of the results of one a mputee and a summary of the most important results of a second subject is p resented. The tests were carried out at normal (1.16 m s(-1)) and fast (1.5 6 m s(-1)) walking speeds. Three dimensional gait analysis was carried out to derive the time curves of the joint angles, intersegmental moments and p ower at the ankle, knee and hip joints at both the prosthetic and sound sid es. A higher first peak of the ground reaction force at the sound side with the Seattle LightFoot compared to that with the Springlite II, may be the result of the lower late stance dorsiflexion angle with the former. Compare d to the other two feet, the Carbon Copy III and the Springlite II showed h igher prosthetic dorsiflexing moments and positive power at late stance, wh ich could assist in the push-off. The 3D intersegmental loads at the ankle and knee can be used as a guide for design and for compilation of standards for testing of lower limb prostheses incorporating flexible feet. (C) 1999 Elsevier Science Ltd. All rights reserved.