Effects of excessive distraction during anterior cervical spine surgery: a systematic review and meta-analysis of clinical outcomes, radiological changes, and complications.

PURPOSE: Excessive distraction (ED) during anterior cervical spine surgeries may improve cervical alignment but higher the risk of postoperative complications. To date, no comprehensive reviews has evaluated the overall impacts of ED across anterior cervical spine surgeries. This study aims to evaluate the impact of excessive distraction (ED) on clinical and radiological outcomes during anterior cervical spine surgeries.

METHODS

A systematic search (PubMed, Europe PMC, Embase, Scopus, Google Scholar; up to March 2025) identified studies reporting distraction and postoperative outcomes after ACDF or CDR. Studies without clinical/radiological outcomes, incomplete statistical reporting, case reports or animal and cadaveric studies were excluded. Data were stratified into early (< 6 months) and late (≥ 6 months) post-operative. Meta-analyses were conducted using Cochrane Review Manager 5.4.1 and R-Studio 4.5.2.

RESULTS

A total of 19 cohort studies encompassing of 1877 patients were included. Excessive distraction was associated with greater post operative neck pain (nVAS: early SMD 0.46; late SMD 0.4, both p < 0.00001), arm pain (aVAS: early SMD 0.28, p = 0.007; late SMD 0.36, p = 0.004), and disability (NDI: early SMD 0.28, p = 0.002; late SMD 0.46, p < 0.00001). No significant differences were found in mJOA or SF-36 scores. Radiologically, ED improved cervical lordosis (C2-C7 Cobb angle: SMD 0.27, p = 0.0005) and range of motion (SMD 0.62, p < 0.00001). However, ED increases risks of adjacent segment degeneration (ASD) (RR 2.98, p < 0.00001), cage subsidence (RR 1.63, p < 0.00001) and heterotopic ossification (HO) (RR 1.99, p = 0.009).

CONCLUSION

Excessive distraction in anterior cervical spine surgeries improves cervical alignment and mobility but worsens pain, disability, and long-term complications. Optimal, not maximal distraction should be targeted to balance alignment benefits with functional outcomes and mechanical safety.