gms | German Medical Science

Objectives/Interrogation: The polysyndactyly of the middle finger usually manifests as the polydactyly of middle finger and at least one of the duplicated middle fingers fused to adjacent fingers. Most cases are distinctly different from the polysyndactyly of the ring finger and haven't appropriate classification to guide surgery. Here we proposed a classification system and discuss the treatment.

Methods: Classified the osseous syndactyly as complex type, cutaneous syndactyly as simple type and classified the polydactyly of middle finger from type I to VIII based on the level of bifid or duplicated skeleton. 19 cases was classified into: Type I 1 cases, Type III 2 cases, Type V 5 cases, Type VI 7 cases, Type VII 4 cases and 3 cases belonged to complex syndactyly. The surgical procedures were performed based on the characteristics of different types. Usually the hypoplastic finger was removed, and the preserved finger was separated from fused adjacent finger by zigzag incisions and using consecutive gull wing flap to construct the two webs at the same time. The final shape and function of affected fingers were followed-up.

Results and Conclusions: All cases were operated successfully. The adjacent fingers in simple type cases were nearly normal. However, all the preserved middle fingers were still suffering from different degree of hypoplasia and abnormality of joints. 4 cases accepted a latter surgery to correct the shape and to improve the function.

We proposed the classification of the central polydactyly, which is similar to the Wassel classification of thumb polydactyly. It will be easily acceptable by most clinicians and be more convenient for academic exchange. There are different characteristic in different types and Type V and VI were more common. Type V usually manifested as bifid proximal phalanxes with both hypoplasia middle fingers but usually minimal lateral deviation. Type VI usually manifested as duplication of proximal phalanxes, usually associates convergence of both middle fingers, similar to the Wassel IV-D type polydactyly of thumb. To select which finger to remove, one should consider to the characteristics of the above different types. The deformity of the preserved finger should be corrected as possible. But in most cases, the residual deformity of the middle finger may still need a second-stage surgery. Skin graft may not be needed in some cases by using consecutive gull wing flap to construct the two webs and transferring the remaining flap from the excised duplication.