64. NEW PROCEDURE FOR THE TREATMENT OF THUMB DUPLICATION TYPE IVD

Abstract

Purpose of the study: Duplication of the thumb is the most common congenital anomaly of the first ray. The characteristic feature of type IV is the diversity of the clinical forms and the presence of certain complex forms particularly difficult to treat (Hung IVD). We propose a new procedure for reconstruction of IVD type thumb duplication.

Material and method: This new procedure was used for thumb reconstruction in two boys with type IVD thumb duplication. Mean age at surgery was 10 months. Surgical technique. The future incisions were traced with a central skin resection removing the most hypoplastic nail entirely (generally the radial nail). At the bone level, a longitudinal osteotomy of the proximal phalanges was made over the entire length to remove the central part and obtain a width for the first phalanx comparable to that of the contralateral thumb. An oblique osteotomy was cut in the base of the distal phalanx of the ulnar hemithumb with resection of a radial corner. The same type of osteotomy was performed at the base of the distal phalanx of the radial hemithumb, but with preservation of the radial corner and resection of the rest of the radial thumb. The proximal hemiphalanges were sutured as were the bases of the distal phalanges. This produced automatic realignment and stabilisation of the interphalangeal joint without an ungueal intervention.

Results: The three children were reviewed at 24, 18 and 12 months. The Horii score was good in all cases.

Discussion: Type IVD duplications of the thumb are difficult to treat and may leave serious sequelae. Our technique is based on the principle of a central resection of the proximal phalanges associated with partial resection of the base of the distal phalanges. This enables realignment and stabilisation of the interphalangeal joint while avoiding the problem of ungueal dystrophy since only one nail is preserved. Our preliminary results are encouraging but must be confirmed with a longer term study.