Abstract: A device for extending a phalangeal bone in the thumb or one of the fingers of a hand. The device includes proximal and distal pairs of bone pins, a pair of screw threaded bars for adjusting the distance between the pairs of bone pins, first and second pairs of guide posts and four pairs of pin retaining members. The guide posts and pin retaining members retain the bone pins in relative alignment as the thumb or finger is progressively extended by adjustment of the bars. Each bar is laterally offset from the corresponding pair of guide posts, while each pair of guide posts is symmetrically positioned relative to the bone pins. The device further includes a brass bushing press fit within each of the apertures which serves to maintain accurate alignment of the bone pins as the thumb or finger is extended. A retaining clip is removably attached at one end of each of the guide posts.