Surgical treatment of the clasped thumb.

We report a series of 12 patients (19 hands) with clasped thumb who underwent surgical treatment. The series is divided into three groups. In the first group, the prominent pathological feature was hypoplasia of the extensor tendons which was treated by tendon transfer. The second group, the arthrogryphotic type, had contracture of the intrinsic muscles of the thumb and shortening of the skin; these needed mainly release operations. In only three hands out of nine was tendon transfer performed. The third group was defined by a combination of skeletal, muscular and tendon hypoplasia. Instability of the M.P. joint and adduction contracture of the first ray were found in all hands of this group. The adduction deformity was corrected by skin-plasty of the first web and the extension was improved by tendon transfers. Only one case needed stabilisation of the M.P. joint. The final results were related to the extent of the contractures and to the age of the patient when treatment started.