Fig. 1

Surgical procedures of LFF. a The cervical spine cord and right nerve root were compressed due to the ossification of posterior longitudinal ligament. b Laminectomy was performed, and the cervical spine cord was partly relieved. But the right nerve root was still compressed due to the cervical ossified posterior longitudinal ligament. c Additional foraminotomies at the symptomatic levels were performed to relieve the nerve root. Part (less than 50%) of the facet joint was removed