Orthopedic fluid damper and method

The invention relates to an orthopaedic aid, in particular to a prosthesis or orthosis comprising an orthopaedic fluid damper with a displacement chamber formed in a housing, with a piston mounted in the displacement chamber, with a fluid reservoir for a fluid, with a return flow conduit connecting the displacement chamber to the fluid reservoir, with a valve that can adopt an open position and a closed position, in which it at least partially closes the return flow conduit, and with a joint that has a first branch and a second branch, wherein the first branch is connected to the housing and the second branch is connected to the piston. A device is also provided for detecting a joint force (FB) acting on the joint, which device is designed to bring the valve to the closed position when the joint force (FB) exceeds a predefined threshold value. The invention also relates to a method for control of the aid and a fluid damper fitted therein.