Hybrid Fixation Approach for Congenital Complex Craniovertebral Junction Anomalies": A Safe and Effective Solution for Challenging Anatomy"

Introduction: Complex congenital craniovertebral junction (CVJ) anomalies present considerable surgical challenges due to a combination of bony and vascular abnormalities. These often include occipitocervical instability, atlantoaxial dislocation (AAD) with C1 assimilation, or hypoplastic C1 lateral masses, along with vascular anomalies such as a high-riding vertebral artery (HRVA), which complicate traditional fixation methods. This study investigates a novel hybrid surgical technique that combines occipitocervical fixation (OCF) with C1 lateral mass (C1-LM) and C2 pedicle (C2-P) screw fixation on the safer side, aiming to provide biomechanically stable alignment in patients with CVJ anomalies.

Methods: This retrospective study included nine patients with congenital CVJ anomalies who underwent hybrid OCF at our institution. The cohort comprised six males and three females, with an average age of 42.1 years. Preoperative evaluations involved the modified Japanese Orthopaedic Association (mJOA) scoring for myelopathy and the modified Ashworth grading for spasticity. Structural anomalies, vertebral artery course, and instability were assessed through plain radiographs, dynamic CT, and MRI. A posterior approach was used for OCF, with C1-LM and C2-P screw fixation on the safe side, and occipital plate and screw fixation on the opposite side where anatomical constraints prevented C1-LM or C2-P screw placement.

Results: All patients presented with neck pain, restricted movement, and neurological deficits; eight had myelopathy. Preoperative mJOA scores indicated severe myelopathy in one patient, moderate in four, and mild in four. Postoperatively, patients achieved successful stabilization and realignment, with no intraoperative vertebral artery injuries. Radiological confirmation of fusion was observed in all cases. Complications were minimal, with no reoperations required.

Conclusion : This hybrid OCF approach with unilateral C1-LM and C2-P screw fixation on the safer side offers an effective treatment strategy for complex CVJ anomalies, providing robust biomechanical stability and reducing the risk of vascular injury. This technique holds promise as a viable option for managing these challenging cases.