Over-correction of Curvature in Surgical Segments Cause the Non-surgical Curvature Loss in One- and Two-level Anterior Cervical Discectomy and Fusion

Abstract Background: In some patients with anterior cervical disecetomy anf fusion (ACDF), the correction degree of cervical curvature after surgery is less than that of the surgical segment curvature, which we defined as non-surgical curvature loss (NSCL). This study aims to elucidate the notification of NSCL and its possible causes. Methods: A retrospective analysis was conducted on 122 patients with one- or two-level ACDF from October 2012 to June 2017. The pre-operative and post-operative Cobb angle of C2-7, surgical segments and non-surgical segments were measured and analyzed by lateral cervical X-ray. Results: All patients were followed up for 22.87±3.15 months. Both one- and two-level ACDF could improve the cervical curvature. In the evaluation of NSCL, it was found that the incidence was 37.50% (27/72) in one-level ACDF and 48.00% (24/50) in two-level ACDF. Furthermore, the NSCL does not spontaneously recover after surgery. By comparing patients with and without NSCL, it was found that patients with NSCL had a significantly higher correction degree in the surgical segments, while the degree of NSCL was significantly and positively correlated with the correction degree of the surgical segments. For patients with a slight correction degree of surgical segment, the cervical curvature was well-improved and maintained post-operatively. Conclusion: In summary, the correction of the surgical segment curvature in ACDF should not be overemphasized, because excessive correction may cause NSCL. Even if the surgical segment curvature is only slightly corrected, a good improvement in cervical curvature can still be attained.