Do the Number of Screws and the Use of a Lateral Fibular Autograft Influence the Union Rate in Ankle Arthrodesis? A Systematic Review

Abstract

Category: Ankle Arthritis; Ankle Introduction/Purpose: Ankle arthrodesis, well-known as a reliable option to treat end-stage ankle osteoarthritis (AO), may be fixed using screws in various configurations. The purpose of this study was to determine whether the number of screws and the use of a lateral distal fibular autograft during the procedure might influence the union and complication rate. We hypothesized that a greater number of screws and the use of a fibular autograft might increase the union rate and reduce the number of complications. Methods: Following the PRISMA-compliant PROSPERO-registered checklist, the Medline, Scopus, Web of Science and Cochrane databases were searched, including studies reporting patients affected by AO and undergone Ankle Arthrodesis (AA) using screws as exclusive fixation method. Data were harvested regarding the cohort (sample size, age, sex, etiology), the study design (type of study, level of evidence), the surgical technique (open/arthroscopic procedure, the number of screws, the use of autograft) and the final outcome (union, complication and reoperation rate) at the longest follow-up. The risk of bias was assessed using the modified Coleman Methodology Score (mCMS) was used to assess the methodological quality of studies. Three groups were built based on the type of fixation: arthrodeses fixed with 2 screws (Group 1, G1), with 3 screws (Group 2, G2), and those augmented with a lateral fibular autograft (Group 3, G3). Results: Twenty series of patients from nineteen studies (732 ankles) were selected (G1=252 ankles, G2=209, G3=271). The pooled proportion estimate revealed a similar nonunion rate in the 2-screw group as compared to the 3-screw group (6% vs 1%; p=0.43) The pooled proportion of complications appeared higher in G1 (18%) than in G2 (8%) but it was not significantly different either (p=0.27). After exclusion of 'symptomatic hardware and screw removal' the difference was still not significant (p=0.62) although it resulted lower in G1 than in G2 (3% vs 8%, respectively). The pooled proportion of nonunions (p=0.48) and complications (p=0.76) did not differ between the AA performed without or with a fibular autograft. Conclusion: Fixation of Ankle Arthrodesis using three screws as compared to two screws seems to be advantageous in terms of reduced risk of nonunion and complications, although the difference did not achieve statistical significance in this study. The use of an adjuvant lateral distal fibular autograft does not seem to significantly increase the chances of fusion as compared to a no- autograft construct. The evidence provided so far is based on retrospective and short-term follow-up studies of moderate methodological quality. Further comparative and prospective analyses are warranted to define how to achieve the best outcome in Ankle Arthrodesis stabilized using screws.