The pedicled pisiform transposition in Kienböck's disease. An anatomical and functional analysis

Anatomic characteristics of the lunate and the pisiform were compared in order to support the use of a pisiform transposition in advanced stages of Kienböck's disease. Fifty lunate and pisiform bone pairs served for morphological and functional investigations. In view of the present results, the pisiform, after a rotation of 90 degrees, should be implanted in the lunate cavity with its longitudinal diameter oriented in the dorsopalmar plane. Despite the small pisiform volume, maintenance of carpal height is assured by its relatively large dorsopalmar diameter. The rotated position takes advantage of existing cancellous structures and improves the conditions of force transmission. Measurements comparing the radii of curvature of the original lunate and the substitute pisiform surfaces show a good correspondence proximally and a reduction of the articular congruity distally, due to the flatness of the pisiform surface.