Anterior odontoid screw fixation indications
Anterior odontoid screw fixation (AOSF) and posterior occipitocervical fusion are both well-accepted techniques for surgical treatment but with unique indications and contraindications as well as varied reported outcomes.
Joaquim et al. reviewed the literature about specific patients and fracture characteristics that may guide treatment toward one technique over the other. AOSF can preserve atlantoaxial motion, but requires a reduced odontoid, an intact transverse ligament, and a favorable fracture line to achieve adequate fracture compression. Additionally, older patients may have a higher rate of pseudarthrosis using this technique, as well as postoperative dysphagia. posterior occipitocervical fusion has a higher rate of fusion and is indicated in patients with severe atlantoaxial misalignment and with poor bone quality. posterior occipitocervical fusion allows direct open reduction of displaced fragments and can reduce any atlantoaxial instability. It is also used as a salvage procedure after failed AOSF. However, this technique results in loss of atlantoaxial motion, requires prone positioning, and demands a longer operative duration than AOSF, factors that can be a challenge in patients with severe medical conditions. Although both anterior and posterior approaches are acceptable, many clinical and radiological factors should be taken into account when choosing the best surgical approach. Surgeons must be prepared to perform both procedures to adequately treat these injuries 1)
Full-Endoscopic Anterior Odontoid Screw Fixation is a feasible and effective option for Odontoid fracture type II treatment. The procedure is less invasive than other techniques and provides clear direct visualization of the involved structures 2).
Direct anterior screw fixation is an effective and safe method for treating recent odontoid fractures (<6 months postinjury). It confers immediate stability, preserves C1-2 rotatory motion, and achieves a fusion rate that compares favorably with alternative treatment methods. In contradistinction, in patients with remote fractures (> or = 18 months postinjury), a significantly lower rate of fusion is found when using this technique, and these patients are believed to be poor candidates for this procedure 3).
Although anterior screw fixation is the ideal choice for type Ⅱ odontoid fractures with anterior superior to posterior inferior fracture line, it may not be the best choice for comminuted or fracture end hardened type Ⅱ odontoid fractures 4).