Reliability of two-point discrimination measurements.

Both moving and static two-point discrimination are valid measurements of functional sensibility in the hand. The present study investigated the interobserver variability of these measurements when two observers used the same testing instrument and the same definition of the testing procedure's end point. In testing 30 nerve-injured patients, interobserver variability was found to vary within 1 mm, or less, for moving two-point discrimination in 93.3% of the measurements and for static two-point discrimination in 86.8% of the measurements. In only two of the 30 measurements of moving two-point discrimination and in four of the measurements for static two-point discrimination were interobserver differences equal to 2 mm. Measurements for both moving and static two-point discrimination were analyzed statistically by linear regression and correlation co-efficient techniques. The measurements for two-point discrimination obtained with the protocol employed in this study were found to have an interobserver reliability at the p less than 0.00001 level.