Air cushion action at the distal end of above-knee stump with a prosthetic socket

The air cushion action over the distal end of residual limb with a prosthetic socket was investigated by experimental measurements of the air pressure during standing and walking and by computational simulation based on finite element methods. The air pressure at the distal-end cavity during walking was found to be in the range of -20 kPa to 17 kPa. The statistical peak pressure was -16.9±2.2 kPa during swing phase and 14.3±2.5 kPa during stance phase. Finite element models have been established to investigate the load transfer between an above-knee stump and the prosthetic socket. An air cavity was assumed to be sealed between the distal end of the stump and the socket. Hydrostatic fluid elements were used to simulate this air cavity. The air pressure predicted for standing is 9 kPa and supports about 12 percent of the total vertical load