A real-time, interactive, 3-dimensional, computer graphic system for the study of one, two, and three degree-of-freedom joints in rotation

A system is described which provides for the arbitrary placement of axes of motion with respect to 3-D anatomical (skeletal) structures. The system extends upon earlier work in the interactive, real-time, simulation of musculoskeletal kinematics. Developed in a UNIX RISC platform, the simulation uses PHIGS Extension to X windows (PEX) to define kinematics models and Motif widgets for control of modeling variables through mouse, control dial, and keyboard interaction. Skeletal structures are triangular shaded polygons developed from Computerized Tomography (CT) scans. Rotational axes of motion represented by long, narrow cylindrical vectors are arbitrarily placed and fixed with respect to skeletal landmarks. Subsequent motion of distal bone segments are then controlled, visualized, and studied for verification of joint congruence and realistic placement. This report describes the simulation applied to the three joints of the thumb (up to six degrees of freedom), the wrist, and the knee (two degrees of freedom each).