RESUMO
Objective To study the correlation between anatomical measurement and CT measurement of adult occipital thickness so as to provide anatomic evidence for the selection of screw length in occipital-cervical fusion. Methods The occipital thickness was measured on the occipital specimens of 10 normal adults in two ways: direct anatomic measurement and CT measurement. Measurements were made on the basis of the McRac' s line and according to a matrix of 66 points following a grid with one cm spacing. The results of both measurements were statistically analyzed using SPSS 10.0. Results The results of both measurements were highly correlated. The external occipital protuberance was the thickest while the region of cerebellar fossa was the thinnest. The regions two cm lateral to the midline between plane Five and plane Six, one cm lateral to the midline between plane Four and at plane Five, and median between plane Three and plane Four were found to have a thickness of more than eight mm. Conclusions The occipital thickness varies with individuals. CT measurement and direct anatomic measurement are highly correlated. Preoperative CT measurements can be reliable evidence for optimal screw placement before performing occipital-cervical fusions.