Optoelectronic and electromagnetic tracking devices are commonly used in biomechanics research. Queen's University and the University of Western Ontario use these devices to study the kinematics of normal and rheumatoid wrists. Queen's University uses the Optotrak®, an optoelectronic motion tracking device on live subjects and the University of Western Ontario uses the Flock of Birds®, an electromagnetic tracking device with cadavers. This research project was done in order to compare the results given by two different motion tracking methods analyzing the same motion.

Optotrak® markers were placed on the skin over bone landmarks on a cadaver arm and MotionStar® receivers were attached directly to the bone. The arm was then passively manipulated through flexion-extension of the wrist and radio-ulnar deviation. Euler angles and helical axis angles were calculated for these motions for both motion tracking systems. The mean and amplitude of the waveforms produced by the two systems were calculated and subsequently compared.

The Euler angle and helical axis angle waveforms produced by both tracking systems were very similar. They had the same general shape with very similar amplitudes. However, there was a small offset in the mean value of the primary Euler CV re was a angles between the two systems. The helical axis angles produced by the two systems are similar, although a small offset between the two systems is also indicated. The Optotrak® optoelectronic motion tracking system, used on the skin, and the MotionStar® electromagnetic motion tracking system, attached directly to the bone give comparable helical axis angle results when examining radio-ulnar deviation.