C2–C3 Anterior Cervical Discectomy and Fusion (ACDF) for Hangman's Fractures with C2 Posterior Dislocation: A Modified Classification of Hangman's Fractures and Technical Notes

Background: The overwhelming majority of hangman’s fractures cause anterior dislocation of C2. Hangman’s fracture with C2 posterior dislocation is extremely rare, only one paediatric case was reported in 2018 to date. This kind of injury cannot be catalogued using current classification schemes and no established treatment recommendations exist. The purpose of this article is to report a rare case of a hangman's fracture with C2 posterior dislocation, which does not fit into existing classification systems, propose a new subtype of hangman’s fractures, and discuss management technical notes for the new subtype to avoid pitfalls. Methods: Description of case, review of relevant literatures and share our experience.Results: A 31-year-old male sustained hangman’s fracture with C2 posterior dislocation after fell into a 50cm deep roadside ditch when riding a motorcycle. Radiograph and computed tomography (CT) on admission showed fractures through both pars of C2 and C2 posterior dislocation. Magnetic resonance imaging (MRI) on admission showed high T2-weighted signal intensity of cervical spinal cord and compression of cervical spinal cord by posterior dislocation of C2 vertebral body. After 5 days of skull traction with 5 kg weight before operation, the dislocation aggravated. A C2-3 anterior cervical discectomy and fusion (ACDF) was performed. At 6 months after operation, bony fusion was achieved, and MRI showed the T2-weighted signal hyperintensity of cervical spinal cord before surgery disappeared.Conclusion: We proposed a new subtype of hangman's fractures here, type IIb hangman’s fractures: type II hangman’s fracture with C2 posterior dislocation. C2–C3 ACDF is recommended for type IIb hangman’s fractures. Traction before surgery is not recommended.