In a suction socket prosthesis, the purpose of the air-release valve is to enable suction suspension to function during which phase of gait?

In a suction socket prosthesis, the purpose of the air-release valve is to enable suction suspension to function during which phase of gait?

• A. Swing phase
• B. Stance phase
• C. Mid-stance
• D. Terminal stance

Answer: (A)

The air-release valve in a suction socket prosthesis serves to keep suction suspension working when the limb is moving through the swing phase. As the residual limb moves without bearing weight, pressure inside the socket can change with limb position. The valve provides a controlled vent so air can escape or enter as needed, preventing disruption of the vacuum and allowing the socket to move smoothly with the leg. This is most critical during swing because there’s no ground reaction force to help maintain the seal, so the system depends on pressure equalization to keep the prosthesis secured for the next heel strike. In stance, bearing weight and external forces help maintain the seal, so the valve isn’t as essential there.

The air-release valve in a suction socket prosthesis serves to keep suction suspension working when the limb is moving through the swing phase. As the residual limb moves without bearing weight, pressure inside the socket can change with limb position. The valve provides a controlled vent so air can escape or enter as needed, preventing disruption of the vacuum and allowing the socket to move smoothly with the leg.

This is most critical during swing because there’s no ground reaction force to help maintain the seal, so the system depends on pressure equalization to keep the prosthesis secured for the next heel strike. In stance, bearing weight and external forces help maintain the seal, so the valve isn’t as essential there.