Crossing the Cervicothoracic Junction

Abstract: The cervicothoracic junction (CTJ) is the site of transition in biomechanical, osseous, and alignment properties of the spine. The interface between the highly mobile, lordotic cervical spine and the rigid, kyphotic thoracic spine results increased the biomechanical stress experienced at this junction. The concentration of stress at this level has led to high rates of failure when instrumenting near or across the CTJ. The changes in osseous anatomy from the cervical spine to the thoracic spine present additional challenges in construct planning. For these reasons, a thorough understanding of the complexity of the cervicothoracic junction is necessary when operating near or across the CTJ. There are multiple options for cervical fixation, including lateral mass screws, pedicle screws, and laminar screws, each with its own advantages and risks. Instrumentation at C7 is controversial, and there is data supporting both its inclusion in constructs and no risk when this level is skipped. Thoracic pedicle screws are the preferred method of fixation in this region of the spine; however, the connection between cervical and thoracic screws can be challenging due to differences in alignment. Transitional rods and rod connectors mitigate some of the difficulties with this transition and have shown to be effective options. Recently, more investigation has looked into the failure of posterior cervical constructs which end at or near the CTJ. The trend in data has favored fixation to T1 or T2 rather than ending a construct at C7 due to the decreased rates of distal junction kyphosis. Although data on patient-reported outcomes with a length of constructs and the lowest instrumented vertebra is scarce, preliminary reports show no difference at this time. As posterior cervical instrumentation continues to increase in frequency, the CTJ will continue to be an area of difficulty in navigation and instrumentation. A thorough understanding of this region is necessary and continued research is needed to improve outcomes. Level of Evidence: Level V.