Thickness map of parietal bone in Korean adults

The parietal bone remains the most common donor site for a bone graft in treating facial bone fractures, especially those involving orbital walls. Despite this potential clinical usefulness, anthropometric data on the parietal bone is lacking. Only one Korean and a few foreign studies report on its thickness, measured at two and three points of each of two parietal bones in a given subject, respectively. These studies, however, fall short of offering enough information for locating the optimal harvest point of the parietal bone for bone grafting. This study was thus aimed at constructing a thickness map that provides the mean parietal bone thickness at various points and determines the difference between them. Eighty-eight parietal bones were obtained from 44 Korean adult skulls for this study. Parietal bone thickness was measured at 15 points, spaced at regular intervals on each parietal bone of a given skull, using a Techlock GM 21 caliper gauge. The mean bone thickness at each of the 15 points of the bone and at the corresponding points of the opposite parietal bone was obtained in all skulls studied. The mean thickness at each point of measurement on two opposite parietal bones was compared using the paired Student's t test. Mean thickness did not differ significantly. The thickness in the same bone varied widely depending on the points of measurement. The thickest part, the posteromedial region of the parietal bone near the lambda, was 6.67 +/- 1.41 mm (mean +/- standard deviation [SD]) thick, and it became thinner toward the diagonal (anterolateral) direction, to the thinnest part, 4.73 +/- 1.19 mm (mean +/- SD) thick, near the pterion. It is hoped that our thickness map can serve as a practical guide for choosing an ideal site on the parietal bone for a bone graft of desired thickness.