Study design: Technique tips and retrospective review of prospectively collected data.
Objective: To describe a technique for centralizing cervical plates using the center of the manubrium as a primary external guide and its alignment with the mandible as a secondary guide.
Summary of background data: Proper alignment of cervical plates is desirable to avoid improper placement of screws and possibly altered biomechanical performance. Large body habitus may portend suboptimal exposure, a limited utility of skin surface landmarks for level determination, and may make it difficult to reliably centralize plates in the coronal plane during anterior cervical surgery.
Methods: We describe a technique that uses the center of the manubrium to determine the midline of the cervical spine and align a line drawn through the manubrium with the center of the mandible to provide a central axis for placing cervical plates along the entire cervical spine. We used anteroposterior fluoroscopy to validate that a line from the middle of the manubrium to the mandible bisected the spinous processes and midline of the vertebral bodies. We prospectively collected data on 39 consecutive patients undergoing anterior cervical discectomy and fusion with cervical plates using this technique.
Results: The mean amount of angulation and translation about a midline axis were 2.24 degrees +/- 1.49 degrees and 1.04 +/- 0.86 mm, respectively. There were no statistical differences among 1-level, 2-level, and 3-level fusions (P > 0.05). The intraobserver correlation coefficient for the measurement technique was R = 0.90 (P = 0.0016).
Conclusion: We validated that the midline of the cervical spine is in line with a straight bovie cord connecting the midline of the manubrium to the midline of the mandible using anteroposterior fluoroscopy. Using this line, we prospectively centered cervical plates with no significant difference between levels. These data may also serve as a benchmark for assessing cervical plate alignment.