A HIGH-ACCURACY 3-DIMENSIONAL COORDINATE DIGITIZING SYSTEM FOR RECONSTRUCTING THE GEOMETRY OF DIARTHRODIAL JOINTS

This paper describes the design and performance evaluation of a three- dimensional (3-D) coordinate digitizing system (3-DCDS) for measuring both soft and hard biological tissue. The system incorporates a visibl e semiconducting laser beam and an X-Y positioning table to directly m easure 3-D coordinates that define surface points. Experiments conduct ed to evaluate the performance of the system showed that it delivers a n accuracy of 0.1 mu m in the Z-direction and 1.4 mu m in the X-Y plan e, and an overall system root-mean-squared error (RMSE) of 8 mu m on s urfaces with slopes of less than 45 degrees. This error is lower than that of previously reported measurement techniques. The 3-DCDS measure s 3-D coordinates of surface points uniformly separated by 500 mu m in the X-Y plane. Because the 3-DCDS is automated, the coordinates are m easured efficiently and the accuracy is independent of operator skill. These highly accurate coordinates can be easily incorporated into nod al values for 3-D finite element models (FEM) of diarthrodial joints. To show the use of the 3-DCDS, the 3-D surface coordinates of human me nisci were measured from a cadaver specimen. (C) 1998 Elsevier Science Ltd. All rights reserved.