浮遊母指を利用し On-Top Plasty で再建を行った母指多指症の 1 例 ～ 術後 15 年の経過追跡 ～

抄録

We describe a rare pattern of thumb duplication consisting of an ulnar-side floating thumb and a radial-side distally hypoplastic thumb. The ulnar thumb was adhered in the first web and had a good nail shape, whereas the nail was absent from the radial thumb. In the presented case, ‘on-top plasty’ was considered the ideal method because combining the 2 thumbs would improve the appearance, position, and length. After the patient reached three years of age, surgery was performed using the ‘on-top plasty’ technique. During the operation, the ulnar-side segment was pedicled and transferred to the radial thumb, which was distally resected. The osteotomy site was then pinned with a 0.7-mm K-wire in the appropriate alignment. The total operative time was 206 minutes. The postoperative course was uneventful. At the 15-year follow-up, the patient had a well-aligned and widely mobile thumb, with a wide first web and excellent cosmetic appearance. The ‘on-top plasty’ technique may be useful for the reconstruction of certain atypical thumb duplications.