Atlantoaxial Spondyloptosis: Report of a Case and Review of the Literature.

Objective: To present an extremely rare case of atlantoaxial spondyloptosis in a neglected case of odontoid fracture, type-2, with complete anterior displacement. The surgical approach in such cases are always challenging. Background: C2 fractures are the most common type of spinal traumatic injury. Among them, odontoid fracture represents the most variable and complicated C2 fractures. When non-operative management is planned, close follow-up and patient compliance are mandatory. Neglecting these cases can lead to complications such as malunion, nonunion and subluxation, of which, atlantoaxial spondyloptosis is the most severe form. Presentation of Case: The patient was a 20-year-old male with the chief complaint of neck pain, progressive quadriparesis, and gait disturbance since 8 months prior to presentation, with Japanese orthopedic association score of 11. Imaging studies showed anterior non-reducible, malunited atlantoaxial spondyloptosis, associated with a type-II odontoid fracture. Methods: The patient underwent open reduction and posterior atlantoaxial instrumented fusion using Harm's technique. One-year Follow-up examination and imaging evaluations revealed complete neurological recovery, with Japanese orthopedic association score of 15, and complete fusion in normal alignment. Conclusion: A posterior-only approach for the management of atlantoaxial spondyloptosis with malunited type-2 odontoid fracture is associated with lower morbidity and fewer complications than anterior or combined approaches, while still achieving all surgical goals. The integrity of the transverse ligament is mandatory in such cases.