New Notations for Better Morphological Distinction of Postaxial Polydactyly of the Foot

There have been many reports on the classification and treatment of postaxial polydactyly of the foot. However, despite its being a common congenital anomaly, there is no universal notation about its morphology.

We performed an analysis of 65 postaxial polydactyly cases from 2004 to 2021. Judgment criteria for deciding the surgical procedure were selected, and the points required for notation were decided. Based on them, we devised a new notation.

The necessary points required for notation were decided based on the following criteria: (1) the presence and level of syndactyly, (2) bifurcation level of the phalanges, (3) the presence of other deformities, and (4) predominant toes. We came up with a new notation and description method. Different types of syndactyly were represented using a horizontal bar, and predominant toes were represented using equality or inequality symbols. The bifurcation level of the phalanges and accessory deformities were additionally recorded (eg, 4-5>-6, Middle, 5,6: External rotation). From this notation, it is obvious which toe should be resected. Furthermore, syndactyly, accessory deformities, and the condition of the phalanges are also easily understood.

Our new notation for postaxial polydactyly consists of some related symbols that are each provided a meaning. This system is simple, especially for easily understanding the morphology, and ideal for daily medical use. We conclude that it could become a universal notation method for cases of postaxial polydactyly of the foot.