Does the Number of Screws Influence the Union Rate in Ankle Arthrodesis? A Meta-analysis and Systematic Review

Objective: The purpose of this study was to determine whether the number of cannulated screws used during ankle arthrodesis (AA) might influence the union and complication rate. Methods: In this Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant PROSPERO-registered systematic review, multiple databases were searched including studies in which patients undergone AA using cannulated screws as exclusive fixation method were followed. Data were harvested regarding the cohort, the study design, the surgical technique, the nonunion, and complication rate at the longest follow-up. Risk of bias was assessed using the modified Coleman Methodology Score (mCMS). Two groups were built (arthrodeses fixed with 2 screws [group 1, G1] vs arthrodeses fixed with 3 screws [group 2 G2]) and compared. Results: Fifteen series of patients from 15 studies (667 ankles) were selected (G1 = 458 ankles and G2 = 209). The pooled proportion estimate revealed a similar nonunion rate in the 2-screw group as compared with the 3-screw group (4% vs 3%; P =.68). The pooled proportion of complications was higher in G1 (19%) than in G2 (8%), but it was not significantly different either (P =.45). After exclusion of “symptomatic hardware and screw removal,” the difference was still not significant (P =.28) although it resulted lower in G1 than in G2 (4% vs 8%, respectively). Conclusions: Using 3 cannulated screws during AA as compared with a 2-screw construct does not significantly reduce the risk of nonunion nor the risk of complications. Level of Evidence: Level IV, Systematic review of level IV