Strategies for Anterior Screw Fixation for Type II Odontoid Process Fracture, and Long-Term Follow-up Results

ABSTRACT

Type II fracture of the odontoid process is the most common form of axis fracture, and because of the difficulty in healing, its results may be fatal. The authors subclassified these fractures as anteriorly displaced(type II-A), posteriorly displaced(type II-P), and non displaced(type II-N). Twelve patients with type II fractures underwent anterior screw fixation : three were type II-A : one, type II-P : and eight, type II-N. The mean duration of follow-up was 29.3 months, and all patients except two showed good alignment and stable fixation : these exceptions were type II-A, with 9mm displacement, and showed delayed failure of screw fixation. All type II-N, II-P, and II-A, with 3mm displacement, were successfully treated. We conclude that selection of the treatment modality should be based on the direction of displacement of odontoid process. For type II-N, II-P and II-A fractures, where displacement is mild, anterior screw fixation is a reliable method, but for type II-A fracture, with severe displacement, posterior fixation should be considered.