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''Infant’s persistent thumb-clutched hand,〔White JW, Jensen WE. The infant’s persistent thumb-clutched hand. J Bone Joint Surg. 1952;34A:680-8〕 flexion-adduction deformity of the thumb,〔Broadbent TR, Woolf RM. Flexion-adduction deformity of the thumb – congenital clsped thumb. Plast Reconstr Surg. 1964;34:612-6〕 pollex varus,〔Miller JM, Pollex varus. A report of two cases. Univ Hosp Bull (Ann Arbor. 1944;10:10-1)〕 thumb in the hand deformity.〔Matev I. Surgical treatment of spastc ‘thumb in palm’ deformity. J Bone Joint Surg. 1963;45B:703-8〕'' Congenital clasped thumb describes an anomaly which is characterized by a fixed thumb into the palm at the metacarpophalangeal joint in one or both hands.〔Miura T: Flexion deformities of the thumb. In Buck-Gramcko D (ed): Congenital Malformations of the Hand and Forearm. London, Churchill Livingstone, 1998, pp 425-429.〕 The incidence and genetic background are unknown. A study of Weckesser et al. showed that boys are twice as often affected with congenital clasped thumb compared to girls. The anomaly is in most cases bilateral (present in both hands).〔 A congenital clasped thumb can be an isolated anomaly, but can also be attributed to several syndromes. == Causes == The thumb contains five groups of muscle and/or tendons: # Extensor tendons (to stretch the thumb) # Flexor muscles/tendons (to bend the thumb) # Abductor muscles/tendons (to move the thumb outwards) # Adductor muscle (to move the thumb inwards) # Opposing muscles (to move the thumb opposite the small finger) In order for the thumb to maintain a normal position, a strict balance between these groups is required. Weak or absent extensors and/or abductors (the extensor pollicis brevis tendon, the extensor pollicis longus tendon or, rarely, the abductor pollicis longus tendon), can cause a disbalance, leading to an abnormal position of the thumb: congenital clasped thumb. There is also the possibility that two tendons are affected simultaneously. The following tendon deviations can induce congenital clasped thumb: * The flexor tendons are too short (the thumb is drawn into the palm) * The abductor tendons are hypoplastic or absent * The extensor tendons are hypoplastic or absent Furthermore, a tight thumb web space (the area between thumb and index finger) can contribute to congenital clasped thumb. The thumb cannot be properly abducted (moved outwards), if the web space is too tight. To summarize, the causes of congenital clasped thumbs may vary between patients and can sometimes be a combination of the preceding components. Treatment should be tailored to all occurring components in order to achieve good results. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Congenital clasped thumb」の詳細全文を読む スポンサード リンク
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