Surgical treatment of unstable odontoid fracture (type II OBAR or HTAL) has progressed, with a range of techniques, the specificities of which need to be known so as to determine their respective roles in the therapeutic arsenal now available. A retrospective study of 22 patients operated on in our center for odontoid fracture between 2005 and 2010 examined the operative techniques employed and analyzed results in the light of the literature, so as to construct an updated decision tree. Two populations could be distinguished: elderly victims of simple fall (mean age, 82.1 years), and younger victims of high-energy trauma (mean age, 42.6 years). Surgical techniques comprised: anterior odontoid screwing (n=14), transarticular C1-C2 screwing on the posterior Magerl (n=3) or anterior Vaccaro approach (n=1), Harms’ posterior C1-C2 arthrodesis (n=3), and occipitocervical arthrodesis (n=3). The overall complications rate for the series was 28%, including one case of non-union, at a mean 11 months’ follow-up. The risk/benefit ratio may be hard to assess in elderly patients. However, anterior screwing restores odontoid anatomy and is the technique of choice in first intention for reducible fracture. In second intention, transarticular C1-C2arthrodesis may be performed on an anterior or posterior approach, depending on local vertebral artery anatomy. Harms’ posterior C1-C2 arthrodesis allows fixation of non-reduced fractures. Occipitocervical arthrodesis is a last resort, as the associated morbidity rate is higher.