A corrective factor for scoring small finger function using the Littler's line and area under a Gaussian curve method

The Littler's line and area under a Gaussian curve method for scoring digital range of motion is an extremely convenient method for evaluating functional return after injury. This method, although being sufficiently accurate for other fingers, leads to a faulty estimation of function in the small finger.

Twenty-six normal hands in 14 volunteers were scored by using the earlier-described method. The statistical significance of the resulting error in small finger function was determined by using the standard error of difference between means. Corrective methods were determined and their statistical validity was established by using the same test.

There was a consistent error in scoring of small finger flexion by about 2.26% using the earlier-described method, which was statistically significant. The error was caused by a radial deviation of the small finger on full flexion. To eliminate the error the proximal reference point of the small finger needs to be shifted radially. The amount of this shift is determined either by using the opposite hand if normal, or by an amount equal to 0.16 times the length of the small finger.

The use of the new reference point for calculating the functional score of the small finger has added to the accuracy of a simple and realistic scoring system for flexion injuries. This eliminates a potential source of error and makes our analysis that much more reliable.