Ossification of the ligamentum flavum in the upper cervical spine: A report of two cases and literature review.

Ossification of the ligamentum flavum (OLF) is rarely observed in the cervical spine, particularly not in the upper cervical spine. The present report describes two cases of OLF combined with cervical myelopathy and provides a literature review with a comparative analysis of previous studies and the present cases. Pre-operative CT, MRI and histological examination were performed to confirm the diagnosis of these patients (A 37-year-old female and 63-year-old male). In both cases, histological examination of surgical specimens revealed OLF. The symptoms of the two patients significantly improved after surgery and no recurrence was observed at 13 months after surgery. Furthermore, the clinical outcomes were satisfactory and the internal fixation was solid in the two cases. Review of the literature suggested that further research is required to reveal the optimal treatment methods for upper cervical OLF.