Novel Atlantoaxial Fusion Technique Minimizes Risks of Severe Nerve Damage
Key findings
- A novel C1–C2 fusion technique makes use of C2 translaminar screws and C1 sublaminar cables to decrease the risk of injury to the vertebral artery and C2 nerve root
- This procedure is technically simpler and avoids the need for C2 nerve root sacrifice or compression
- Other advantages of the technique are direct visual monitoring of laminar cortical bone to avoid breach, and no need for fluoroscopy or navigation
- Three patients underwent the procedure without postoperative complications
In 2004, a technique for treating atlantoaxial fusion was introduced, and it greatly reduced the risk of injury to the vertebral artery and C2 nerve root. The procedure incorporated C2 into subaxial fusion constructs by placing bilateral, crossing C2 translaminar screws.
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A Massachusetts General Hospital team has improved on that technique by fixing C1 sublaminar cables to C2 translaminar screws for C1–C2 fusion. This procedure is technically simpler, decreases the risk of vertebral artery injury even more and avoids the need for C2 nerve root sacrifice or compression.
Jean V. Coumans, MD, a neurosurgeon at Mass General, and the rest of the research team describe their procedure in Operative Neurosurgery. Once C1 is exposed, a soft cable is passed under C1 in a caudal to rostral direction. When the translaminar C2 screws are in place, short, straight rods are affixed to the screw heads. Appropriate selection of rod length and position allows the surgeon to tailor the C1-C2 angle. Next, the rod connectors are inspected to ensure that they terminate in the axial plane passing through the C1 posterior arch.
The cable is then threaded through the holes of the connector rods and tightened using a crimping device and fastener. While using the crimper, the surgeon can visualize the incremental reduction as C1 is translated posteriorly toward the rod connectors. Variable cable tension allows patient-specific reduction in cases of increased atlantodental interval.
Dr. Coumans and his colleagues note that the approach allows for a direct view of posterior and anterior laminar cortical bone and recognition of a breach. In addition, there is no need for fluoroscopy or navigation because the instrumentation is placed under direct visualization.
This technique was successfully used in three elderly patients whose anatomy posed a challenge to traditional C1-C2 fusion. One had chronic degenerative atlantoaxial instability and two had been injured in falls. There were no postoperative complications.
The authors conclude that this adapted technique is relatively easy and safe. They plan to expand its use, but they warn that it is not appropriate in the setting of C1 arch fractures, and it should be used only with caution in patients with a bifid C1 arch.
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