The causes of restraint of thumb web motility are congenital hypoplasia, trauma, and burns. The latter two, since they usually include fibrosis and injury to local skin that could be used for repair, are the most serious. In treatment abduction must be maintained after release of the restraint. New tissue coverage must follow accepted principles of proper placement of suture lines where plastic procedures are used, and adequate restoration of subcutaneous tissue, as well as skin, where that is indicated. Details of how to select and fashion the appropriate flaps are set forth.