The Impact of Positive Regional Sagittal Alignment on Outcomes in Posterior Cervical Fusion Surgery

Keywords: cervical spine, pain, spinal fusion, spine surgery, outcome

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     Positive spinal sagittal malalignment has repeatedly shown to correlate with pain and disability in thoracolumbar fusion.
     This study evaluated the relationship between cervical sagittal alignment and postoperative outcomes for patients receiving multi-level cervical fusion.
     From 2006-2010, 113 patients received multi-level cervical fusion for cervical stenosis, myelopathy, and kyphosis.
     Radiographic measurements at intermediate follow-up included: (1) C1-C2 lordosis, (2) C2-C7 lordosis, (3) C2-C7 sagittal vertical axis (C2-C7 SVA), (4) Center of gravity of head SVA (CGH-C7 SVA), and (5) C1-C7 SVA. Health related quality of life measures (HRQOL) included neck disability index (NDI) and SF-36 physical component (PCS) scores. Pearson correlation coefficients were calculated between radiographic and HRQOL measures. Improvement in NDI scores following surgery were evaluated by categorizing scores into accepted standard intervals of disability.
     80% of patients experienced an improvement of NDI scores or remained the same compared to preop. PCS scores improved by 22.0±37.5%. Both C2-C7 SVA and CGH-C7 SVA negatively correlated with PCS (r=–0.43,p<0.001 and r=–0.36,p=0.005, respectively). C2-C7 SVA positively correlated with NDI scores (r=0.20,p=0.036).C1-C2 lordosis constituted 76.0±15.8% of total cervical lordosis. C2-C7 SVA positively correlated with C1-C2 lordosis (r=0.33,p=0.0003). Degression models predicted a threshold C2-C7 SVA value of approximately 40mm, beyond which correlations with NDI scores were most significant.
     This is a retrospective study.
     Positive cervical sagittal malalignment, measured by C2-C7 SVA, negatively affects HRQOL scores following multi-level cervical fusion.
     Our findings are the first to demonstrate that, similar to the thoracolumbar spine, the severity of disability increases with positive sagittal malalignment following surgical reconstruction.


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