GAIT ANALYSIS OF DYSVASCULAR BELOW-KNEE AND CONTRALATERAL THROUGH-KNEE BILATERAL AMPUTEES - A PRELIMINARY-REPORT

Four elderly peripheral vascular insufficiency below-knee amputees, av erage age 58, underwent contralateral through-knee amputation for gang rene. All four became household ambulators with end-weight bearing des igned prosthetic sockets and four-bar linkage knees. Gait analysis was performed with two AMTI (Newton, Mass) Biomechanics Force Platforms a nd a Watsmart Motion Monitoring System (Waterloo, Ontario). All four w ere observed to apparently ''lock'' the four-bar linkage prosthetic kn ee into extension during midstance and double limb support phases of g ait. All subjectively felt that their through-knee limb was their more stable limb. Weight-bearing occurred during 63 % of the gait cycle on the below-knee limb, 54 % on the through-knee limb, and 17 % in doubl e limb support. Walking propulsion, as measured by forefoot impulse, w as similar in the two limbs. The first peak of vertical force, corresp onding to the elevation of the center of body weight as it passes over the weight-bearing limb, averaged 98 % of body weight on the through- knee limb and only 93 % on the below-knee limb. The second peak, corre sponding to the kinetic energy of the falling trunk and muscle functio n providing linear acceleration of the center of body weight during pr opulsion, averaged 96 % of body weight on the through-knee limb, and o nly 73 % on the below-knee limb. Progression of the center of pressure , a qualitative measure of limb stability, was more orderly in the thr ough-knee limbs. In a preliminary laboratory gait analysis, elderly pe ripheral vascular insufficiency below-knee amputees who became househo ld walkers following contralateral through-knee amputation derived gre ater stability from their through-knee limbs without the expected loss of walking propulsion. The authors conclude that, 1) unilateral below -knee amputees who are projected to be marginal walkers following cont ralateral limb amputation may benefit from the stability afforded by t hrough-knee amputation of the second limb; and 2) elderly patients who possess. the ability the heal an amputation at the below-knee level, but project to be marginal walkers, may also benefit from the stabilit y in walking with an end-weight bearing prosthesis afforded by through -knee amputation, without the expected loss of walking propulsion.