ABSTRACT
Introduction: There are various diseases and anomalies in humans which require occipitocervical fusion using medial orlateral occipital screw placement along with rod or plate placement.[1] There are many ongoing arguments regarding the safearea for screw placement on the occiput during fusion techniques. Morphological analysis of occipital bone thickness providesconfidence in placing screws. Here, we try mapping occipital bone using computed tomography (CT) which would benefit forsafe fusion in population of southern Tamil Nadu.Materials and Methods: We randomly selected the CT scans of 50 patients in the age group of 20–60 years, and occipitalbone thickness mapping is done and tabulated and compared with the previous studies from different demographical areas.Results: The maximum thickness of the occipital bone was at the level of the external occipital protuberance (EOP) at 16.2 mm.Areas with thicknesses >8 mm were more frequent at the EOP and up to 2 cm in all directions, as well as up to 1 cm in alldirections at a height of 1 cm inferiorly, and up to 3 cm from the EOP inferiorly in males and it’s up to 2 cm in females. Themale group tended to have a thicker occipital bone than the female group, and the differences were significant around the EOP.Based on these data, there are 10 safe points for males which include: M0, M1, M2, M3, L1, L2, R1, R2 at level 0, L1, and R2at level 1 and 9 safe points for female which include all the above except M3.Conclusion: There is variability in the thickness of occipital bone in adult people from different demographic areas andthere is also a significant difference between male and female patients. Hence, this study helps in pre-operative planning inoccipitocervical fusion in people of this region.