Figure 1.

Hand X-ray showed that height of the trapezial space before surgery. Radiographic reference points for measurement of the height of the CMC space. Line (a) is the line projected through the radial articular surface of the index metacarpal the trapezium. Line (b) is the line tangent to the thumb metacarpal base and perpendicular to line (a). Line (c) is the line tangent to the distal extreme of the scaphoid and perpendicular to line (a). The distance between line (b) and line (c) is the height of the CMC space. CMC = carpometacarpal.