Three-dimensional reconstruction and CAD of intramedullary stem of individual metacarpophalangeal joint prosthesis

Objective: To develop a new system of computer-aided design (CAD) for individual metacarpophalangeal joint prosthesis based on rapid prototyping technique. Methods: A hand of cadaver was scanned with PLUS-4 spiral computed tomography (CT). Then the transaxial 2D image data of digitus metacarpophalangeal joint were reconstructed into 3D digitized contour data by 3DMSR that was designed by ourselves. Then, the intramedullary stem was designed in software of Surface 9.0. Results: The 3D contour image of metacarpophalangeal joint presented was reconstructed by 3DMSR and edited by Surface 9.0 easily for CAD of individual metacarpophalangeal joint. The intramedullary cavity was like choanoid. The intramedullary stem longitude of articular head and fossa were 47.31 and 35.20 mm. The intramedullary stem fit cavity. The model fit anatomical shape. Conclusion: The 3D contour image of metacarpophalangeal joint can be obtained by spiral CT scanning, and the digitized data can be applied directly to CAD of individual artificial joint and subsequently rapid prototyping fabricating. In addition, the reconstruction method is simple and can be applied widely to clinical implant fabricating practice of orthopaedics.