Transoral atlantoaxial reduction plate internal fixation with transoral transpedicular or articular mass screw of c2 for the treatment of irreducible atlantoaxial dislocation: two case reports.

STUDY DESIGN: Retrospective report of two surgical cases and review of the literature.

OBJECTIVE: To report the clinical application of transoral atlantoaxial reduction plate (TARP) internal fixation with a novel technique of transoral transpedicular or articular mass screw of C2 in the treatment of irreducible atlantoaxial dislocation and basilar invagination with ventral spinal cord compression.

SUMMARY OF BACKGROUND DATA: Current surgical treatments for IAAD have various disadvantages, such as posterior decompression followed by atlantoaxial or occipitocervical fusion with unsatisfactory decompression, transoral decompression, and one-stage posterior instrumentation needing two approaches although with satisfactory decompression, resection of dens and/or clivus with potential risk of spinal cord injury and CSF leakeage.

METHODS: TARP system with a novel technique of transoral transpedicular screw or articular mass screw of C2 was designed and employed for two patients with irreducible atlantoaxial dislocation, during which one case was with basilar invagination. The histories of the cases and the novel technique of transoral articular mass screw and transpedicular screw insertion of C2 were reported in detail.

RESULTS: The two case examples demonstrate the efficacy of this one-stage single transoral approach to the surgical treatment of irreducible anterior atlantoaxial dislocation with spinal cord compression especially in the case of basilar invagination. The role of the TARP in affecting and maintaining the reduction while promoting successful fusion is illustrated.

CONCLUSION: The authors' one-stage anterior procedure employing the TARP for the surgical treatment of irreducible anterior atlantoaxial dislocation and basilar invagination was effective in these two cases. This method was able to avoid the need for dens and clivus resection and/or a posterior instrumentation and fusion procedure. The technique of transoral articular mass screw and transpedicular screw insertion of C2 was valuable for transoral atlantoaxial plate internal fixation.