1545. Distal And Proximal Extensions in Long-Segment Posterior Fusion involving the Cervicothoracic Junction: Their Impact on Short-Term and Long-Term Outcomes

Authors: Wataru Ishida, MD; Adam D'Sa, BS; Arun Chandra, BS; Joshua Casaos, BS; Alexander Perdomo-Pantoja, MD; Seba Ramhmdani, MD; Nicholas Theodore, MD; Daniel Sciubba, MD; Ali Bydon, MD; Timothy Witham, MD; Sheng-fu Lo, MD (Baltimore, MD)

Introduction: Long-segment posterior spinal fusion involving the cervicothoracic junction carries higher complication rates due to its biomechanical stress when compared with non-junctional regions. To overcome this problem, the extension of fusions from C7 to the thoracic spine and/or C3 to C2 is sometimes considered. However, the impact of the caudal/rostral extension alone or the combination of both on clinical outcomes has not been thoroughly explored in the literature yet. Methods: Retrospective clinical record review from 2010 to 2016 identified 162 patients who underwent long-segment posterior fusion (C3-C7, C3-T2, C2-C7, or C2-T2) for degenerative diseases, trauma, or infection with a minimum one-year follow-up period. They were sub-classified into the two groups: fusions ending in the cervical spine (Group 1, n=60) and those ending in the thoracic spine (Group 2, n=102). Rates of pseudarthrosis, adjacent segment disease (ASD), and overall surgical revision were collected and statistically analyzed. Results: There were no statistically significant differences in baseline characteristics such as age, BMI, and gender. Group 2 had significantly higher estimated blood loss and longer operative time and hospital stay than those in Group 1. Rates of all three primary outcomes were comparable between the two groups. In multivariate analysis, C7 to T2 extension (Group 1 versus Group 2) independently reduced rates of pseudoarthrosis at the most distal level (P=0.02) and distal ASDs (P=0.04), whereas C3 to C2 extension was independently protective against pseudoarthrosis at the most proximal level (P=0.01) and proximal ASDs (P=0.03). Conclusion: The rates of pseudoarthrosis and ASDs at distal and proximal segments were independently reduced by C7 to T2 and C3 to C2 extension, respectively. The judicious selection of the upper-most fusion level and the lower-most fusion level should be weighed against the detrimental short-term outcomes in treating this patient population with unique biomechanical considerations.