Background: Nonunion is a postoperative complication after ankle arthrodesis (AA), which leads to increased morbidity and revision rates. Previous studies have identified risk factors for nonunion following AA, but no meta-analysis has been performed to stratify risk factors based on strength of evidence.
Methods: Abstracts and full-text articles were screened by 2 independent reviewers. Relevant data were extracted from the included studies. Random effects meta-analyses were summarized as forest plots of individual study and pooled random effect results.
Results: Database search yielded 13 studies involving 987 patients were included, and 37 potential risk factors for nonunion. Meta-analysis found 5 significant risk factors for nonunion post-AA. Strong evidence supports male gender (OR: 1.96; 95% CI: 1.13-3.41), smoking (OR: 2.89; 95% CI: 1.23-6.76), and history of operative site infection prior to arthrodesis (OR: 2.40; 95% CI: 1.13-5.09) as predictors for nonunion following AA. There was moderate evidence supporting history of open injury (OR: 5.95; 95% CI: 2.31-15.38) and limited evidence for preoperative avascular necrosis (OR: 13.16; 95% CI: 2.17-79.61) as possible risk factors for nonunion.
Conclusion: The results of our meta-analysis suggest that male gender, smoking, and history of operative site infection have strong evidence and that history of open injury and avascular necrosis also have evidence as risk factors for nonunion. Surgeons should be cognizant of these risks when performing AA and closely follow up with patients with the aforementioned risk factors to ensure postoperative success.
Levels of evidence: Level V: Systematic review of cohort and case-control studies.
Keywords: ankle arthrodesis; nonunion; risk factors; systematic review.