The project set out to use a very precise three dimensional tracking system to identify changes in joint condition for use in clinical assessment. Untried and untested the CODA-3 was brought into the department and put through a six month period of validification in order to evaluate it's capabilities. These are described in detail in the text. Once satisfied that the equipment was capable of measuring minute rapidly changing position of it's prismatic markers, pilot studies were devised to assess it's ability to reproduce the results from well recognised gait-analysis techniques. It gave promising results. The next task was to determine which set of parameters we could derive using CODA-3 that would be of use in describing the kinematics of the diseased and/or prosthetic knee for use as a tool in clinical assessment. Using FORTRAN, subroutines were written and run on a DEC LSI-11 computer, to collect, store and analyse the x, y and z coordinates of the eight CODA landmarks. It was hoped that by appropriate siting of the markers the velocities and accelerations of the segments comprising a joint could be monitored throughout the gait cycle. The resultant patterns of these parameters were plotted out, and the actual data values stored. It was hypothesised that weaknesses in a joint, whether or not detectable by clinical examination would, at points in the gait cycle of maximum joint loading be seen as ectopics in the smooth waveform of the acceleration and velocity of the profiles expected from the normal knee. The results the author presents would suggest that if the limitations of this particular model could be overcome (as it is reported they will be) then the technique has the capability of highlighting abnormalities in a joint. The author is doubtful however that these same weaknesses could not be detected by the clinician. The system may well have other applications related to this area of work and these are discussed.