A Novel Device for the Measurement of Functional Finger Pinch Movement Discrimination

Abstract

Proprioception provides feedback that is vitally important for motor control. A deficiency in joint proprioception is thought to be associated with various upper limb rheumatological disorders. Currently, there is a lack of a portable device that could be used for measuring functional proprioception at the fingertips in the field. Therefore, a novel portable device for measuring pinch movement discrimination between index finger and thumb of either hand was constructed. This device is manually operated and requires the subject to make an absolute judgment of a joint position, choosing which one of five pre-experienced positions is being presented to them, with trials given in a random order. The 5 physical differences used were between 1.22 and 2.42cms. Reliability analysis was performed over a 7-day interval, with 8 healthy young adult volunteers. The discrimination scores, measured as the Area Under the Curve (AUC), for the group showed a mean (SD) of 0.794 (0.544) and 0.794 (0.549) on days 1 and 8, respectively. The day 1 and 8 reliability assessed with the interclass correlation coefficient ICC(3,1) was 0.85. Nondominant hands showed better pinch discrimination on the two days, with AUC values of 0.800 and 0.810 compared with 0.788 and 0.778, but these differences were not statistically significant (p>0.05). No difference in pinch movement discrimination was found between sexes. The ease of use and portability of the novel device for measuring functional proprioception at the fingertips described in this note make it ideal for measuring hand functional proprioception as part of clinical and epidemiological studies. The mid-range AUC discrimination scores found with healthy young adults mean that factors thought to diminish (eg. hand injury) or improve (eg. having expert finger skills) discrimination could be detected with the device.