ABSTRACT
【Objective】 To quantitatively analyze the surgical freedom of odontioectomy via endoscopic endonasal approach. 【Methods】 Seven adult head specimens were dissected by the endoscopic transnasal approach to the sellar region and craniocervical junction. The center of sellar floor (CenSF), opticocarotid recess (LOCR), foramen magnum, atlas, atlas-occipital joint and tip of odontoid process (TOP) were exposed. The surgical freedom of TOP was calculated by using the spatial coordinate positioning system of neuronavigation, and compared with that of LOCR and CenSF. 【Results】 CenSF and LOCR were common landmarks in the endonasal endoscopic approach. When the surgical freedom between TOP and CenSF and LOCR was compared, it indicated that ① The angle of attack on axial plane (AAAP):There was a significant difference among TOP, LOCR and CenSF (5.7 ° vs. 6.9 ° vs. 8.5 °, P=0.004). The comparison between the two groups showed that TOP was less than CenSF (P=0.003). ② The angle of attack on sagittal plane (AASP): There was a significant difference among TOP, LOCR and CenSF (6.3° vs. 7.0° vs. 9.5°, P=0.009). The TOP was less than CenSF (P=0.008). ③ There was no statistical significance between TOP and LOCR in surgical freedom (P=0.604, P=0.688). 【Conclusion】 Endoscopic transnasal approach can provide sufficient surgical freedom for odontoidectomy.