Effect of Cervicothoracic Junction LIV Selection on Posterior Cervical Fusion Mechanical Failure: A Systematic Review and Meta-Analysis

Study design: Systematic review and Meta-analysis.

Objective: Analyze and summarize literature evaluating the role of C7, T1, and T2 lowest instrumented vertebra (LIV) selection in posterior cervical fusion (PCF) and if this affects the progression of mechanical failure and revision surgery.

Summary of background data: Literature evaluating mechanical failure and adjacent segment disease in the setting of PCF at or nearby the cervicothoracic junction (CTJ) remains limited with studies reporting conflicting results.

Materials and methods: Two reviewers conducted a detailed systematic review using EMBASE, PubMed, Web of Science, and Google Scholar on June 28, 2021, for primary research articles comparing revision and complication rates for posterior fusions ending in the lower cervical spine (C7) and upper thoracic spine (T1-T2). The initial systematic database yielded 391 studies, of which 10 met all inclusion criteria. Random effects meta-analyses compared revision and mechanical failure rates between patients with an LIV above the CTJ and patients with an LIV below the CTJ.

Results: Data from 10 studies (total sample=2001, LIV above CTJ=1046, and LIV below CTJ=955) were meta-analyzed. No differences were found between the 2 cohorts for all-cause revision [odds ratio (OR)=0.75, 95% CI=0.42-1.34, P <0.0001] and construct-specific revision (OR=0.62, 95% CI=0.25-1.53, P <0.0001). The odds of total mechanical failure in the LIV below CTJ cohort compared with the LIV above CTJ cohort were significantly lower (OR=0.38, 95% CI=0.18-0.81, P <0.0001).

Conclusion: The results show patients with PCFs ending below the CTJ have a lower risk of undergoing total mechanical failure compared with fusions ending above the CTJ. This is important information for both physicians and patients to consider when planning for operative treatment.

Level of evidence: Level I.