Predictive factors of surgical adjacent segment disease in the cervical spine: A nested case-control study

Nested case-control study.

Radiological adjacent segment degeneration is reported in a significant proportion of patients operated on following ACDF. Only a part of them will experience clinical symptoms, ultimately requiring a second cervical spine surgery (_SASD). Our retrospective observational study, with prospective data collection, aims at considering the potential influence of cervical sagittal balance on post-ACDF second surgery based on postoperative imaging follow-up. Four key potential predictive factors were evaluated between cases and controls.

Between January 1st, 2014, to January 1st, 2020, 1078 patients were operated on for ACDF in the Spine Department of Lille University Hospital. We identified 19 cases and 76 matched controls. Cases were defined as follow: >18 y/o, operated on for a second ACDF related to a _SASD. Controls patients did not undergo a second cervical surgery during the study period.

The prevalence of _SASD was 1.76%. Neither the cervical sagittal axis (p = 0.12), nor the cervical lordosis (p = 0.40) were related to _SASD. However, we reported a strong tendency for the numbers of levels operated on and the postoperative local kyphosis to be risk factors of _SASD (respectively p = 0.056 and p = 0.06).

We did not report a clear impact of the cervical spine balance parameters such as cervical lordosis or cSVA on the risk of second cervical surgery at 2 years. Though, we highlighted the potential correlation between the initial number of cervical spine levels operated on and the occurrence of sASD and the presence of early local kyphosis.