Abstract: A rearfoot post comprises a stop segment and an elastic segment operatively coupled along an axis of rotation. The stop segment is fabricated from a firm or rigid material. The elastic segment compresses and expands in response to foot motion. The elastic segment can include an elastomer or a spring. In some embodiments, the stop segment and the elastic segment are operatively coupled by a hinge, and the axis of rotation coincides with the axis of the hinge. Depending on service applications, a plate can be attached to the bottom of the stop segment and to the bottom of the elastic segment. Embodiments of the rearfoot post also include a heel cup. A heel cup with a flat bottom is advantageous for controlling stability of the foot and reducing shock on the heel.