A system and method for sensing movement of a device associated with a limb. In one example, a prosthetic or orthotic system includes a sensor assembly configured to measure movement of a component of the system in a single direction while substantially isolating negative effects of forces and/or loads in other directions. For instance, the sensor assembly may be advantageously coupled to a pivot assembly configured to substantially mimic a natural ankle joint. The sensor assembly may monitor rotation of a foot unit about an axis of a pivot pin of the pivot assembly and disregard other movements and/or forces. For example, the sensor assembly may include a potentiometer that detects rotation of an associated elongated bellow portion about the axis, wherein the bellow portion includes a plurality of ridges configured to substantially eliminate effects of radial and/or axial forces.