Background: The dorsal rectangular flap technique has been widely used for the correction of syndactyly. In this method, however, the linear scar along the palmar border of the webspace may lead to secondary contracture and web creep. Some modifications have been advocated for breaking these linear scars. In this study, these modifications were evaluated biomechanically with the finite element method. Methods: Based on computed tomography findings of seven adult hands, three scar models were created: the dorsal rectangular flap, the dorsal flap with palmar-based triangular flap, and the dorsal flap with V-shaped tip. Forced displacements were applied to mimic the hand-opening motion, and scar stresses and web displacement were investigated. Results: The maximal stress of the scar was significantly greater in the dorsal rectangular flap group than in the other groups (dorsal flap with palmar-based triangular flap, p = 0.046; dorsal flap with V-shaped tip, p = 0.018). The web was displaced most distally in the dorsal rectangular flap group compared with the other groups (dorsal flap with palmar-based triangular flap, p = 0.043; dorsal flap with V-shaped tip, p = 0.043). There was no significant difference between the dorsal flap with a palmar-based triangular flap group and the dorsal flap with a V-shaped tip group. Conclusions: The authors' results indicate that both the palmar-based triangular flap and the V-shaped tip flap work well. It is strongly recommended that any break should be made in the palmar edge of the webspace for prevention of web creep.
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