Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


This dissertation describes the development of a computer graphical simulation of thumb kinematics as a clinical design tool. The simulation utilizes a realistic data structure of the thumb bones, an optimized model of joint kinematics, and a variety of experimental cadaver measurements. It was developed with a concurrent processing arrangement in which graphical transformations and interactive manipulations are handled on a distributed graphics system, and musculoskeletal dynamics calculations are carried out on a minicomputer. The thumb simulation includes interactive entry of patient related data, simulation of two types of tendon transfer operations, calculation and display of resultant muscle mechanics during movement, and a summary and analysis of transfer results. The skeletal structure was derived from controlled longitudinal radiographs of an excised cadaver specimen mounted in an index fixture. Radiographs were traced and digitized in a vector format suitable for the graphics system. These longitudinal views constitute the bottom level nodes in a hierarchical structure built to simulate the motions of the distal three bones. The structure was improved by replacing each set of raw vectors with a mathematical spline applied to each view. This provided both a smoothing of the data and a decrease in vector density. Real time interfacing to the thumb structure for manipulation and viewing was designed on the graphics system to provide rotation and translation of the entire view and rotations at each joint. Excursions and moment arms are based on an optimized model of the carpometacarpal joint. Other experimental measurements such as muscle mass, mass fraction, tension fraction, and muscle fiber lengths derived from fresh cadaver studies are built into the simulation as determinants of overall moment and muscle excursion capacities. This interactive system, combined with the mathematical model, results in a realistic depiction of thumb motion in normal and impaired states. Individual anatomical parameters, and muscle pulley and insertion points can be altered resulting in the simulation of typical clinical conditions as well as muscle-tendon transfer operations. This type of computer modeling, utilizing a realistic, three-dimensional data structure, meaningful musculoskeletal kinematics, and interactive programming, shows great potential for bringing mathematical modeling into a useful clinical application.