Position sense acuity of the upper extremity and tracking performance in subjects with non-specific neck and upper extremity pain and healthy controls.

OBJECTIVE We aimed to investigate whether position sense acuity of the upper extremity and tracking performance, pen pressure and muscle activity in a tracking task are affected in subjects with neck and upper extremity pain. METHODS Twenty-three subjects with neck and upper extremity pain and 26 healthy controls participated in the study. Position sense acuity of the upper extremity was measured while subjects pointed at targets, without vision of their arm and hand. In the computer tracking task, subjects were instructed to position a cursor within a moving target dot, using a pen on a tablet. RESULTS Position sense acuity of the upper extremity was impaired in subjects with pain. Their variable error was 20-30% larger than in healthy controls. Subjects with pain also showed reduced tracking precision. Both the mean and the standard deviation of the distance to target were significantly larger in subjects with pain than in healthy controls, 10% and 13% respectively. No differences between groups were found in pen pressure and muscle activity during tracking. CONCLUSION The results suggest that subjects with pain are limited in performing precision tasks due to impaired position sense of the upper extremity, but do not compensate with increased effort.