Exclusion of Ossified Ligaments Behind C2 Vertebra Combined with Anterior Controllable Antedisplacement and Fusion for Cervical Ossification of the Posterior Longitudinal Ligament Extending to C2 Segment

Abstract

We sought to introduce an anterior surgical technique for cervical ossification of posterior longitudinal ligament (OPLL) extending to C2. A total of 29 patients with multilevel OPLL extending to C2 underwent surgery from January 2016 to January 2019. The rationale of our surgical technique is to transect the ossified ligament at the level of C2/3, dividing OPLL into 2 parts. OPLL behind the C2 vertebra is reserved as "focus exclusion," and OPLL below C2 is performed anterior controllable antedisplacement and fusion. Neurologic condition was evaluated using the Japanese Orthopaedic Association scoring system and its improvement ratio. Radiologic assessment included type and extent of OPLL, occupying rate, thickness and length of ossified mass, and curvature of spinal cord. Surgery- and implant-related complications were recorded. The mean Japanese Orthopaedic Association score increased from 9.4 to 15.8 points at last follow-up, with a significant improvement (P < 0.01). The mean preoperative length of the ossified mass behind C2 was 15.4 mm, and its thickness was 2.2 mm, with no significant progression at last follow-up (15.3 mm and 2.2 mm, P > 0.05). There was also no statistical difference in OPLL thickness at the largest occupying rate level between preoperation and last follow-up (7.4 mm vs. 7.3 mm, P > 0.05). Four patients presented with cerebrospinal fluid leakage, 1 with screw displacement, and 1 with dysphagia. For patients with cervical OPLL extending to C2, exclusion of ossified ligaments behind C2 combined with anterior controllable antedisplacement and fusion below C2 is an effective and alternative technique.