Association between sagittal balance and adjacent segment degeneration in anterior cervical surgery: a systematic review and meta-analysis

Abstract

Background ASD is a relatively common degenerative alteration after cervical surgery which occurs above or below the fused segment. In addition, some patients may need reoperation to treat severe ASD after the primary surgery. It was considered that sagittal balance is correlated with postoperative clinical outcomes; however, few studies have reported the influence of sagittal balance on ASD. The present study is designed to investigate whether sagittal balance impacts the pathology of adjacent segment disease (ASD) in patients who undergo anterior cervical surgery for degenerative cervical disease. Methods Databases including Pubmed, Embase, Cochrane library, and Web of Science were used to search for literature published before June 2018. Review Manager 5.3 was used to perform the statistical analysis. Sagittal balance parameters before and after surgery were compared between patients with and without ASD. Weighted mean difference (WMD) was summarized for continuous data and P < 0.05 was set for the level of significance. Results A total of 221 patients with ASD and 680 patients without ASD from seven articles were studied in this meta-analysis. There were no significant differences in most sagittal balance parameters between the two groups, except for postoperative cervical lordosis (CL) (WMD -3.30, CI -5.91, − 0.69, P = 0.01). Conclusions Some sagittal balance parameters may be associated with the development of ASD after anterior cervical surgery. Sufficient restoration of CL may decrease the incidence of ASD. The results in present study needed to be expanded carefully and further high-quality studies are warranted to investigate the impact of sagittal balance on ASD.

Morphologic Change of Cortico-Cancellous Allograft used for Anterior Cervical Discectomy and Fusion

“…This may have been caused by compensation of the unoper-ated segments, which warrants further evaluation. 29,30 Although the pseudarthrosis and subsidence rates of this study are higher than generally thought, recent reports have demonstrated that the pseudarthrosis rate after ACDF could have been underestimated, with the incidence reaching 13.0% to 22.6% for one-level operation and 45.5% to 47.0% for three-level operation. [31][32][33] The subsidence rate could have been detected with increased sensitivity since subsidence was assessed using multiple CT images.…”

“…This may have been caused by compensation of the unoper-ated segments, which warrants further evaluation. 29,30…”

Association of cervical sagittal alignment with adjacent segment degeneration and heterotopic ossification following cervical disc replacement with Prestige-LP disc

“…In addition, for every 1° increase in the postoperative CL, there was an 8% reduction in the risk of complications when ASD and HO were considered together. Our results were consistent with those in the previous meta-analysis by Zhang et al, 11 who reviewed five studies and found that the postoperative degree of CL was significantly lower in patients who underwent anterior cervical spine surgery and developed ASD compared with those who did not develop ASD by the last follow-up. Based on our findings and those of previous studies, we believe that it is important to maintain normal cervical alignment after Prestige-LP CDR.…”

“…Multiple studies have shown that there is a relationship between cervical sagittal balance and neck pain, cervical disc degeneration, and the outcomes of ACDF. 3,4,7,[9][10][11][12]21,26 However, the importance of cervical sagittal parameters in CDR is rarely noted. In addition, the cervical sagittal alignment and its impacts on clinical outcomes after Prestige-LP CDR has been rarely studied.…”

“…Several studies have shown that the above cervical sagittal alignment parameters are associated with patient outcomes after anterior cervical spine surgeries, such as anterior cervical discectomy and fusion (ACDF). [6][7][8][9][10] For instance, poor CL and kyphotic FSUAs are risk factors for adjacent segment degeneration (ASD), 8,11,12 and a high T1s is associated with pseudarthrosis and implant subsidence following ACDF. 6,10 However, the relationship between cervical sagittal balance and other kinds of anterior cervical spine surgeries, such as cervical disc replacement (CDR), is poorly understood.…”