Improving C1-C2 Complex Fusion Rates: An Alternate Approach

Abstract

The surgical repair of atlantoaxial instabilities (AAI) presents complex and unique challenges, originating from abnormalities and/or trauma within the junction regions of the C1-C2 atlas-axis, to surgeons. When this region is destabilized, surgical fusion becomes of key importance in order to prevent spinal cord injury. Several techniques can be utilized to provide for the adequate fusion of the atlantoaxial construct. Nevertheless, many individuals have less than ideal rates of fusion, below 35%-40%, which also involves the C2 nerve root being sacrificed. This suboptimal and unavoidable iatrogenic complication results in the elevated probability of complications typically composed of vertebral artery injury. This review is a retrospective analysis of 87 patients from Cedars Sinai Medical Center in Los Angeles, California, who had the C1-C2 surgical fusion procedure performed within the time frame from 2001 to 2008, with a mean follow-up period of three years. These patients had presented with typical AAI symptoms of fatigability, limited mobility, and clumsiness. Diagnosis of C1-C2 instability was documented via radiographic studies, typically utilizing computed tomography (CT) scans or x-rays. All patients had bilateral C1 lateral masses and C2 pedicle screws. In addition, the C1-C2 joint was accessed by retracting the C2 nerve root superiorly and exposing the joint by utilizing a high-speed burr. The cavity that is developed within the joint is packed with local autologous bone from the cephalad resection of the C2 laminae. Fusion of the C1-C2 joint was achieved in all patients and a final follow-up was conducted approximately three years postoperative. Of the 87 patients, two presented with occipital headaches resulting from the C1 screws impinging on the C2 nerve root. The issue was rectified by removing instrumentation in both patients after documenting complete fusion via radiographic studies, with complete resolution of symptoms. No vertebral artery or spinal cord injuries were reported as a result of the minor complication. Overall, we aim to describe a safe and reliable alternative technique to fuse C1-C2 instability by focusing on intra-articular arthrodesis complementing instrumentation fixation. This methodology is advantageous from a biomechanical standpoint secondary to axial loading, as well as the large surface area available for arthrodesis. Additionally, this technique does not involve the resection of the C2 nerve root, resulting in low risk for vertebral artery or spinal cord injury.

Early Outcomes of Bone Autografting in the Bilateral Atlantoaxial Joints Applied in Posterior Fusion Surgery

“…The atlantoaxial joint carries most of the head weight, similar to spinal intervertebral discs 25 . The mechanical force could generate stress on the bilateral atlantoaxial joints and posterior bone graft when patients were kept in a sitting or upright position.…”

“…The atlantoaxial joint carries most of the head weight, similar to spinal intervertebral discs. 25 The mechanical force could generate stress on the bilateral atlantoaxial joints and posterior bone graft when patients were kept in a sitting or upright position. The longitudinal pressure load between atlantoaxial vertebrae is mainly transmitted down through the atlantoaxial lateral mass, 13 , 26 and the bone graft is prone to fuse and reconstruct with specific stress stimulation according to Wolff's law.…”

Clinical Outcomes of Atlantoaxial Dislocation Combined with Osteoporosis Using Posterior Atlantoaxial Rod, Screw Fixation, and Posterior Interfacet Fusion: A Retrospective Study of 21 Cases

“…Similar to anterior cervical interbody graft, posterior interfacet fusion can be performed between atlantoaxial lateral masses, which bear a certain compression load, and the contact area of the graft is large, so it is more conducive to the fusion of the graft. One study has reviewed 87 patients with atlantoaxial dislocation who underwent atlantoaxial lateral mass fusion, and the success rate of postoperative fusion was as high as 100% [ 30 ]. In addition, we reduced the difficulty of reduction by further atlantoaxial release during the operation.…”

Novel Technique for C1–2 Interlaminar Arthrodesis Utilizing a Modified Sonntag Loop-Suture Graft With Posterior C1–2 Fixation

“…Ghostine et al also reported a similar approach in which arthrodesis along the entire C1-2 joint is used to complement instrumented fixation, but without sacrificing the C2 nerve roots, resulting in lower rates of occipital headaches in patients postoperatively. 13 Another method of atlantoaxial fixation that obviates the need for C2 nerve root sacrifice or compression by using C2 translaminar screws in combination with C1 sublaminar cable suspension for C1-2 fusion in the setting of atlantoaxial instability has also been described. 14 Here we report an operative nuance, which combines the Goel-Harms fixation technique with a safe and facile, modified Sonntag arthrodesis technique for securing interlaminar bone graft between C1 and C2.…”

“…This approach results in higher fusion rates, but was associated with increased rates of postoperative occipital headaches and may increase the risk for vertebral artery injury. Ghostine et al [ 13 ] also reported a similar approach in which arthrodesis along the entire C1–2 joint is used to complement instrumented fixation, but without sacrificing the C2 nerve roots, resulting in lower rates of occipital headaches in patients postoperatively. Another method of atlantoaxial fixation that obviates the need for C2 nerve root sacrifice or compression by using C2 translaminar screws in combination with C1 sublaminar cable suspension for C1–2 fusion in the setting of atlantoaxial instability has also been described [ 14 ].…”