Abstract
Dynamic assessment of the wrist motion and the specific angles are difficult using the conventional methods. We wanted to adapt and assess the repeatability of the Fas-trak system for continuous monitoring of three dimensional (3 D) wrist movements.
Twenty seven volunteers, aged 18 to 30 years were asked to perform predetermined tasks. The exclusion criteria were previous history of wrist trauma or joint disease. The transmitter was mounted on the dorsum of the forearm while the sensor was placed over the third metacarpal head. The protocol of three tasks was developed. Task 1 measured maximal flexion, extension, radial and ulnar deviation of the wrist. Task 2 involved picking up an object and moving it across a barrier. Task 3 involved the writing simulation. The comparison between the left and the right wrists indicated suitability of the system to be used on either of the limbs. Repeated measurements on the right wrist provided an assessment of repeatability of the Fastrak system.
The Fastrak system was successful in acquiring data in 3 D. The transmitter and the sensor were easy to attach and were of no discomfort to the subjects. As expected the maximum movement was noted in the flexion-extension plane. The total arc of movement in the flexion-extension plane was 127.1 degrees and 69.7 degrees in the radio-ulnar plane. There was no statistically signifi-cant difference between the movements in the left and the right wrists, even when the effect of dominance was considered. The lift and move task showed that most subjects utilised three-fourths of the total possible radio-ulnar movement, but only one-thirds of the total flexion and extension. The writing simulation revealed a substantial variability between subjects. The Fastrak system revealed variation up to 3 degrees in the means of range of movements, while measuring wrist movements.
The current study showed that the Fastrak system is a user-friendly and repeatable device, which could be used in everyday clinical use. It has the potential to be used for evaluation of the diseased wrist and the results of therapeutic interventions, operative or otherwise.
Correspondence should be addressed to Mr Carlos Wigderowitz, Senior Lecturer, University Department of Orthopaedic and Trauma Surgery, Ninewells Hospital and Medical School, Dundee DD1 9SY.
