BACKGROUND: Haptic pens can now be used to collect electronic data for drawing and writing tasks. This approach can be used to develop hand precision exams for rehabilitation settings. In this preliminary study, we assess hand precision by having participants attempt to trace circles of varying sizes. PURPOSE: Have participants use a haptic pen to trace circles of varying sizes and determine if there are significant differences in error scores (between small and large circles). METHODS: Seventeen healthy control subjects participated in the study (23.53±4.03 yrs). Participants drew using the dominant hand while sitting at a desk in a standard office chair. The forearm was harnessed to the desk to decouple elbow and shoulder movements; therefore, a participant could only move the wrist to complete tasks. A haptic pen (Touch, 3D Systems, USA) was used to trace existing paths of 1 large circle (D=6.5 cm) and three small circles (d=2.5 cm). The total circumference of three smaller circles was equal to the circumference of the larger circle. For data analysis, the error scores were assessed at 1° intervals. Specifically, at each degree, a line was established from the perimeter of the circle to the participant’s traced circle. The error was defined as the distance (along the line) from the circle and the participant’s trace. The overall error score for large circle was the mean of the 360 individual error scores, and the overall error score for the small circles was the mean of the error scores (for the three smaller circles). A dependent t-test was used (𝛂;;=0.05) to determine if there were significant difference in error scores between the large and small circles. RESULTS: Participants had broad ranges of error scores for the large circle (7.0mm to 65.8mm) and small circle (7.0mm to 39.9mm). Five of the 17 participants had very small error scores (˂ 20mm) for both circle sizes. The dependent t-test revealed no significant difference (p=0.10) in overall error scores between the large circle (2.55±0.17mm) and small circle (1.84±0.11mm). CONCLUSION: Tracing ability was highly variable among the control participants. Changing the dimension of the circle did not significantly change the error scores for the group. This suggests that there was a similar degree of difficulty for the two circle sizes. Future studies should thoroughly assess reliability for circles (of varying sizes) and learning effects.

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