A Simple and Useful Method for Evaluating Pincer Nail Deformity

Abstract

We propose a new method for evaluating the severity of pincer nail, in which the narrowed nail width ratio (NNWR) is calculated based on the measurements of actual nail width, distance between the distal lateral nail edges, and apparent proximal nail width. The method revealed that the average distal NNWR of the big toenails of 24 healthy volunteers was 80.5%, whereas that of 24 patients with pincer nail averaged 32.4%, indicating a significant difference between the two groups. Furthermore, the average increase in NNWR in six weeks after the correction therapy using a superelastic wire was 23.2 points, comparable to the clinical improvements of the overcurvature. In conclusion, this evaluation method using NNWR enabled objective judgement of not only the severity of pincer nail, but also the therapeutic effects of the correction treatment.