母指形成不全（type Ⅲ-B）に対し血管柄付き足趾PIP関節移植により再建を行った1例

Reconstruction of a Type Ⅲ-B Hypoplastic Thumb Using a Free Vascularized Proximal Interphalangeal Joint of the Second Toe : Case Report

　抄録：母指形成不全に対し足趾関節移植により機能再建を行った1例を経験したので報告する．患者は5歳，女児．右母指形成不全．X線所見で中手骨基部からCM関節基部にかけて欠損したBlauth分類Type Ⅲ-Bの母指形成不全であった．右第2趾PIP関節をドナーとして関節移植による機能再建を行った．ドナー側は右腓骨骨幹部からの遊離骨移植にて再建した．関節移植後8カ月で対立再建のためHüber-Littler法による短母指外転筋の移行および固有示指伸筋腱，中指浅指屈筋腱の移行を追加した．関節移植後39カ月の時点で，移植関節は完全に生着しPIP関節の骨端線も開存しており，移植関節部は骨長で約13％の成長がみられたが，ドナー側では移植骨は吸収され短縮変形を生じた．文化的背景などから指数の減少が好まれない場合には，母指形成不全に対して足趾関節移植による母指機能再建術はよい適応となる．

　Reconstruction of a Blauth Type Ⅲ-B hypoplastic thumb with use of a free vascularized proximal interphalangeal joint from the second toe was performed in a 5-year-old female. The toe joint was transferred to obtain stabilization of the carpometacarpal joint of the affected thumb. The donor toe was reconstructed by free fibular bone graft. Eight months following the toe joint transfer, multiple tendon transfers were performed to mobilize the reconstructed thumb. The abductor digiti minimi was transferred to the radial base of the proximal phalanx to restore opposition of the thumb. The flexor digitorum superficialis of the middle finger was transferred to the palmar base of the distal phalanx for restoration of flexion of the thumb and the extensor indicis proprius was also transferred to the dorsal base of the proximal phalanx to restore extension of the thumb. Thirty-nine months after the vascularized toe joint transfer, the transferred joint had survived completely and had been growing well up to 48％ increase of the length with normal open epiphysis. The transferred toe joint worked as the carpometacarpal joint without any evidence of osteoarthritic changes. Concerning the donor toe, the grafted fibula was absorbed gradually and remarkable shortening occurred. Although reconstruction of the donor site has been a great problem, we believe that reconstruction of an unstable hypoplastic thumb with use of a free vascularized toe joint transfer in combination with multiple tendon transfers is a good alternative for patients in cultures where the presence of five digits is important.