Gait analysis of dysvascular below-knee and contralateral through-knee bilateral amputees: a preliminary report.

Four elderly peripheral vascular insufficiency below-knee amputees, average age 58, underwent contralateral through-knee amputation for gangrene. All four became household ambulators with end-weight bearing designed prosthetic sockets and four-bar linkage knees. Gait analysis was performed with two AMTI (Newton, Mass) Biomechanics Force Platforms and a Watsmart Motion Monitoring System (Waterloo, Ontario). All four were observed to apparently "lock" the four-bar linkage prosthetic knee into extension during midstance and double limb support phases of gait. 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 double limb support. Walking propulsion, as measured by forefoot impulse, was similar in the two limbs. The first peak of vertical force, corresponding 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, corresponding to the kinetic energy of the falling trunk and muscle function providing linear acceleration of the center of body weight during propulsion, averaged 96% of body weight on the through-knee limb, and only 73% on the below-knee limb. Progression of the center of pressure, a qualitative measure of limb stability, was more orderly in the through-knee limbs.(ABSTRACT TRUNCATED AT 250 WORDS)