Impact of Cervical Spine Deformity on Preoperative Disease Severity and Postoperative Outcomes Following Fusion Surgery for Degenerative Cervical Myelopathy

Study Design. Sub-Analysis of the prospective AOSpine CSM North America and International studies. Objective. The aim of this study was to investigate the impact of cervical spine deformity on pre-And postoperative outcomes in fusion surgeries for degenerative cervical myelopathy. Summary of Background Data. The associations between cervical alignment and patient outcomes have been reported but are not well established in a myelopathy cohort. The impact of deformity correction in this population also needs to be elucidated. Methods. A total of 757 patients were enrolled in two prospective international multicenter AOSpine studies. Among those who underwent anterior or posterior fusion surgeries, pre-And 1-year postoperative upright neutral lateral radiographs of cervical spine were investigated to measure C2-7 Cobb angle and C2-7 sagittal vertical axis (SVA). Patient outcome measures included the modified Japanese Orthopedic Association score for myelopathy severity, Neck Disability Index (NDI), and Short-form 36 (SF-36). These scores were compared between patients with and without cervical deformity, which was defined as C2-7 Cobb >10° kyphosis and/or SVA >40mm. Results. A total of 178 patients were included with complete pre-And postoperative radiographs. SVA significantly increased postoperatively (27.4 vs. 30.7mm, P=0.004). All outcome measurement showed significant improvements above minimal clinically important differences. 23.6% of the patients had cervical deformity preoperatively; preoperative deformity was associated with worse preoperative NDI scores (45.7 vs. 38.9, P=0.04). Postoperatively, those with deformity exhibited significantly lower SF-36 physical component scores (37.2 vs. 41.4, P=0.048). However, when focusing on the preoperatively deformed cohort, we did not find any significant differences in the postoperative outcome scores between those with and without residual deformity. Conclusion. There was a significant association between cervical deformity and both preoperative disease severity and postoperative outcomes; however, no impact of deformity correction was shown. Level of Evidence: 2