Fibrous Nonunion of Odontoid Fractures: Is It Safe To Accept Nonoperative Management? A Systematic Review

Nonoperative management of odontoid fractures can result in solid fusion, unstable nonunion, and fibrous nonunion. Odontoid fractures with fibrous nonunion will not demonstrate dynamic instability on imaging studies. However, the safety of accepting this outcome has been debated. We have provided, to the best of our knowledge, the first systematic review of the existing literature to explore the safety of allowing fibrous nonunion as an acceptable outcome for odontoid fractures. The PubMed and Embase databases were searched in January 2022. The outcomes were extracted and categorized according to the mortality, neurologic sequelae, pain, neck disability index, and satisfaction. Of a total of 700 abstracts screened, the full text of 79 reports was assessed, with 13 studies included. Of the included patients, 141 had had a fibrous nonunion, all described in observational studies. The follow-up ranged from 0.6 to 5.8 years. None of the 141 patients had experienced a neurologic event. One patient had died of trauma-related issues; however, causality was not reported. Most of the studies had reported good to excellent pain scores. Most of the neck disabilities reported had ranged from mild to moderate in severity. However, 1 study of 5 patients had reported severe disability. All the patients reported good or excellent satisfaction. The evidence we found supports that it is safe to forgo surgery for carefully selected patients with nonunited odontoid fractures when near-anatomic alignment is present, dynamic instability is lacking on imaging studies, the neurologic examination findings are normal, and the risk of neck injury is low. Further study is needed to define the full natural history of fibrous nonunion of odontoid fractures.