Objective: This study sought to determine whether a relationship exists between caudal instrumented level and revision rates, neck disability index scores, and cervical alignment in patients undergoing multilevel posterior cervical fusion.
Methods: This study examined a dataset of all patients undergoing posterior cervical decompression and fusion at ≥3 levels, terminating between C4 and T4, between January 2010 and December 2015, with at least 12 months of clinical follow-up. Patients were separated into cohorts based on caudal level of the fusion: C6 (or more cranial), C7, T1, or T2 (or more caudal). Revision rate, neck disability index score, sagittal vertical axis, T1 slope, and cervical lordosis were recorded. Linear regression and multivariate analysis were performed to identify independent predictors of patient outcomes and disparities between ending constructs in the cervical and the thoracic spine.
Results: The overall revision rate was 10.8% (n = 24). No statistically significant difference in the revision rate was identified between fusions terminating at C6 or cranial, C7, T1, or T2 and caudal (P = 0.74). Revision correlated strongly with increased sagittal vertical axis (P = 0.002) and T1 slope (P = 0.04). Increased neck disability index score correlated with revision rate (P = 0.01), cervical kyphosis (P < 0.001), and increased sagittal vertical axis (P = 0.04).
Conclusions: This study suggests that constructs terminating in the proximal thoracic spine have similar revision rates, postoperative neck disability index scores, and radiographic measurements as those terminating in the cervical spine. Poor cervical alignment, as evidenced by increased sagittal vertical axis, cervical kyphosis and T1 slope, predicts need for revision and of poorer clinical outcomes.
Keywords: Cervical kyphosis; Cervicothoracic fusion; Cervicothoracic junction; Multilevel posterior cervical fusion; Posterior cervical fusion; Sagittal vertical axis.
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