A prosthetic device includes an internal frame assembled from multiple longitudinal members and multiple transverse members that are substantially planar in character and are arranged to be joined together. A medially arranged opening is defined in each transverse member, and is substantially registered with openings of adjacent transverse members to form a longitudinal passage, such as may be useful to receive an actuator and/or other items. At least some transverse members differ from one another in one or more of shape, length, or width. A covering member may be provided over the internal frame. Rear-facing gaps in transverse members may receive one or more elements such as dampers, batteries, or the like.