Patent ID: 8611504

Claim:
An apparatus comprising: a radiolucent dimensioned grid plate having a top surface and a bottom surface, at least one of the top and bottom surfaces having a plurality of dimensioned radio-opaque horizontal and vertical lines formed thereon, the horizontal and vertical lines being spaced apart as in a grid pattern with identical distance between each subsequent vertical line in a horizontal direction and each subsequent horizontal line in a vertical direction, and an oblique grid line at an angle of between about 30 to 50 degrees relative to the horizontal lines, and a medial-lateral slot formed in one of the top and bottom surfaces of said grid plate to be parallel to the horizontal lines; at least one of a plurality of support plates configured to retain said dimensioned grid plate by receiving one of the top and bottom surface on a front or back surface of at least one of the plurality of support plates; and a central axis pin connected to at least one of said plurality of support plates perpendicularly relative to a plane of the at least one support plates, wherein said medial-lateral slot is configured to retain the central axis pin therethrough, wherein the medial-lateral slot is configured to allow medial-lateral translation of the grid plate relative to a horizontal line of said support plates, the horizontal line being generally aligned with the medial-lateral slot, wherein the medial-lateral slot is configured to allow the grid plate to rotate around the axis of said central axis pin relative to the support plates, and wherein the medial-lateral slot is comprised of a plurality countersunk grooves that are configured to retain said central axis pin to the grid plate.