Calvarial thickness and its relation to cranial bone harvest

Background: The purpose of this study was to define the variability in skull thickness from location to location and from individual to individual in a large number of human skulls. Method: Skull thickness was measured in multiple areas of the calvaria in 281 dry skulls from the Hamman-Todd osteological collection (Cleveland Museum of Natural History, Cleveland, Ohio). A total of 40 points were determined over the frontal, occipital, and parietal bones, with a higher number of points concentrated on the latter. Repeated measures analysis of variance models were used to assess the effects of covariates (individual variables) on skull thickness and location. Result: A statistically significant pattern of increased thickness toward the posterior parietal bones was seen in all subgroups. The mean thickness of the skull across all locations was 6.32 mm (SEM, 0.07 mm) and ranged from 5.3 mm (SEM, 0.09 mm) to 7.5 mm (SEM, 0.09 mm). Age was not found to be a significant predictor of mean skull thickness. Differences between male and female skulls were greater toward the rear of the parietal bones. Conclusion: The thickest area of the skull is the parasagittal posterior parietal area in male skulls and the posterior parietal area midway between the sagittal and superior temporal line in female skulls. An accurate map of the skull thickness representing the normative data of the studied population was developed. It is hoped that this topographic map will assist the surgeons in choosing the safest area of cranial bone graft harvest, thus increasing the safety of the procedure.