Abstract
The aim of the present study was to evaluate the prevalence of calcification of the oblique atlanto-occipital ligaments (OAOLs, arcuate ligaments) relative to gender, age, and degree of calcification. Lateral cephalometric radiographs of 255 subjects presenting for orthodontic evaluation were reviewed. Population size was determined by power analysis. Two calibrated raters reviewed the films and classified the degree of calcification using a standardized rating scale. Class 1 ligaments demonstrated no calcification, Class 2 ligaments were less than half calcified, Class 3 ligaments were at least half calcified, and Class 4 ligaments were completely calcified. Of the subjects, 158 were Class 1 (62%), 70 were Class 2 (20%), 18 were Class 3 (7%), and 29 were Class 4 (11%). There was no evidence that the degree of ligamentous calcification of the arcuate ligaments differed by gender (p>0.10) or age (p=0.8891). This suggests that the anomaly is congenital in origin.