Staged conversion after circular ring external fixation in adult open long-bone fractures: A systematic review

Background: Circular ring external fixation is frequently used in high-energy open long-bone fractures, yet prolonged frame retention is associated with pin-tract morbidity and patient burden. Staged conversion to internal fixation is therefore attractive, but concerns persist regarding deep infection and nonunion. We systematically reviewed the evidence on outcomes and timing of staged conversion following circular ring fixation in adult open long-bone fractures. Methods: This review followed PRISMA 2020 guidelines and was registered in PROSPERO (CRD42021023282). PubMed, Embase, Cochrane Library, and Scopus were searched from inception to December 2025. We included studies of adult open long-bone fractures managed with circular ring external fixation, comparing definitive ring fixation versus staged conversion to internal fixation or reporting outcomes after conversion. Owing to clinical and methodological heterogeneity, a narrative synthesis was performed. Primary outcomes were reported deep infectious complications (including fracture-related infection when explicitly defined) and union. Results: Eight studies (303 patients) were included; however, only six acute traumatic open-fracture cohorts contributed to the primary synthesis, while two reconstructive/infected nonunion series were considered contextual only. Across the limited acute-trauma data, staged conversion was associated with fewer frame-related complications in some cohorts, but any effect on deep infectious complications and union remained uncertain because of inconsistent definitions, small sample sizes, and confounding by indication. Conclusions: The current evidence base is dominated by small, retrospective and methodologically heterogeneous studies. In acute traumatic open long-bone fractures treated with circular ring fixation, staged conversion after soft-tissue stabilization may reduce frame-related morbidity but whether it influences deep infection or union remains uncertain. Present data should therefore be interpreted as low-certainty observations rather than reliable comparative evidence. Level of evidence: Level IV