A simple camera tracking virtual reality system for evaluation of wrist range of motion

Clinicians assess wrist and hand function to identify pathology, monitor effectiveness of treatment, and determine the readiness to return to work and other activities. The goniometer, the conventional evaluation tool used to assess range of motion (ROM), is most suited to the measurement of passive and active joint ROM under conditions that entail static, nonfunctional movements. Instruments that measure ROM during complex, dynamic tasks may encumber the movement. We have adapted a simple optical tracking device that uses a lowcost webcam to track two diodes, referred to as the Virtual Wrist Tracker (VWT), to assess wrist ROM in 30 subjects, aged 18-65 years; fifteen patients had sustained orthopaedic injuries and 15 were control subjects. ROM was assessed by a standard goniometer and by the VWT under two conditions: visual auditory feedback and auditory pacing feedback. The results of test-retest analysis of control subjects demonstrated good reliability for the VWT during wrist extension and moderate reliability during wrist flexion. High, significant correlations were found between the ROM for wrist extension and flexion as measured by a goniometer and via the VWT in the research group and for wrist extension but not for wrist flexion in the control group. A repeated measures ANOVA mixed design showed no significant differences in wrist extension ROM or in wrist flexion ROM during the performance of the task with visual and auditory feedback versus a task with auditory pacing, nor was there interaction effects between task type and group during extension and flexion. Wrist ROM in either direction increased as the participant progressed from one target rectangle to the next; statistically significant interaction effect was found between ROM in target position and group indicating that the difference between the targets in the control group was significantly different than in the research group. Finally, both groups enjoyed performing the VWT tasks but the control subjects felt greater presence, success and control. The VWT appears to be a reliable and valid tool for assessing wrist ROM during dynamic activities.