Relative Risks and Benefits of Crossing the Cervicothoracic Junction During Multilevel Posterior Cervical Fusion: A Multicenter Cohort

OBJECTIVE: To compare the clinical and radiographic outcomes and complications in patients undergoing multilevel posterior cervical fusion surgery, ending at C7 or crossing the cervicothoracic junction (CTJ). METHODS: A total of 96 patients undergoing multilevel posterior cervical fusion surgery ending at C7, T1, or T2 were screened. The patients who fulfilled the inclusion criteria were divided into 2 groups based on the lower instrumented vertebra (LIV) level: group C7 (ending at C7) and group T1-T2 (crossing the CTJ). The radiographic and clinical outcomes were compared between the 2 groups, and the risk factors for instrument failure at LIV were investigated. RESULTS: In total, 73 patients (76%) completed at least 1 year follow-up and divided into group C7 (n = 43) and group T1-T2 (n = 30). Preoperative and postoperative radiographic parameters, the Japanese Orthopaedic Association score, and patient-reported outcomes were not significantly different between the 2 groups. Significantly longer surgical time, increased blood loss, and higher incidence rates of perioperative or postoperative complications were noted in group T1-T2. On the other hand, the incidence of instrument failures at LIV was significantly higher in group C7. Multivariate analysis showed that ending at C7, skipping screw insertion at the proximal vertebra adjacent to LIV, and a large postoperative cervical sagittal vertical axis (>40 mm) were risk factors for instrument failure at LIV. CONCLUSIONS: Crossing the CTJ during multilevel posterior cervical fusion surgery reduced instrument failu res at LIV, but increased the surgical invasiveness and perioperative and postoperative complications.