A prosthetic device including an internal frame assembled from multiple longitudinal members and multiple transverse members, wherein each member is substantially planar and defines peripheral slots, and wherein the longitudinal members and transverse members are arranged to mate with one another to join the longitudinal members with the transverse members. In certain embodiments, a first group of longitudinal members is radially arranged relative to a central axis extending through the transverse members, and a second group of longitudinal members is tangentially arranged relative to the central axis, preferably with lateral edges of the second group of longitudinal members extending between two different longitudinal members of the first group of longitudinal members to provide enhanced torsional rigidity. An outer shaping member, which may be tubular in shape, may be arranged to cover at least a portion of the internal frame.