The condition, described by Blundell Jones and designated by him delta phalanx, is a manifestation of polydactylism. A tubular bone of the hand or foot with a proximal epiphysis becomes the site of origin of an extraskeletal ray. This bone takes on a peculiar shape since its proximal epiphysis is shared with the supernumerary ray. An unacceptable angular deformity often develops in the digit. Early osteotomy and bone graft is recommended particularly in those fingers in which the shape of the involved bone is more triangular.
Copyright 1967 by The Journal of Bone and Joint Surgery, Incorporated