Biomechanics of odontoid fracture fixation. Comparison of the one- and two-screw technique.

Direct anterior screw fixation of odontoid fractures has become more prevalent clinically. No biomechanical study, however, has determined whether one or two screws should be used. This study measured the stability of the odontoid process after fracture and internal fixation with one or two screws. Internal fixation of Type II odontoid fractures did not restore the original stability of the intact specimen, direct internal fixation with one or two screws provided 50% of the stability of the unfractured odontoid, and no significant differences between the one- and two-screw technique was found under loading to failure, although the two-screw technique provided increased stiffness in extension loading.