Clinical and surgical results related to anterior-only multilevel cervical decompression and instrumented fusion for degenerative disease

INTRODUCTION: Anterior-only multilevel cervical decompression and fusion surgery (AMCS) on 3-5-levels is challenging due to potential complications. Also, outcome predictors after AMCS are poorly understood. RESEARCH QUESTION: We hypothesize that in patients with at most mild/moderate cervical kyphosis (CK) of the cervical spine, restoration of cervical lordosis (CL) positively influences clinical outcomes. METHODS: Analysis of consecutive patients presenting with symptomatic degenerative cervical disease or non-union undergoing AMCS. We measured CL from C2 to C7, Cobb angle of fused levels (fusion angle, FA), C7-Slope, and sagittal vertical axis C2-7 (cSVA, stratified into ≤4cm∖>4cm). Patients with excellent outcome were grouped in BEST-outcomes and with moderate/poor outcomes in WORST-outcomes. RESULTS: We included 244 patients. Fifty-four percent had 3-, 39% 4-level and 7% had 5-level fusion. At mean follow-up of 26 months, 41% of patients achieved BEST-outcome and 23% WORST-outcome. Complications and reoperation rates did not significantly differ. Non-union significantly influenced outcomes. The number of patients with non-union was significantly higher in patients with a preoperative cSVA>4cm (OR 13.1 (95%CI:1.8-96.8). Our model, based on the multivariable analysis with WORST-outcome as outcome variable showed a high accuracy (NPV=73%, PPV=77%, specificity=79%, sensitivity=71%). DISCUSSION AND CONCLUSION: In 3-5-level AMCS, improvement of FA and cSVA were independent predictors of clinical outcome. Improvement of CL positively influenced clinical outcomes and rates of non-union.