A prosthetic or orthotic system including a magnetorheological (MR) damper. The MR damper may be configured to operate in shear mode. In one embodiment, the MR damper includes a rotary MR damper. A controller is configured to operate the damper. A mobile computing device may be adapted to intermittently communicate configuration parameters to the controller. A method of configuring a prosthetic or orthotic system is also disclosed.