What is the optimal timing for bone grafting during staged management of infected non-unions of the tibia? A systematic review and best evidence synthesis

Purpose: To summarize the best available evidence with regards to timing of staged bone grafting for infected tibial non-union, and to extract evidence-based criteria indicating when bone grafting can be safely performed. Methods: Medline, Embase, Scopus, and Google Scholar were searched, and publications of evidence Level I-IV from 2000 to 2020 were included. Risk of bias was assessed with the Cochrane Collaboration's Risk of Bias Tool and ROBINS-I tool. Study quality was assessed with the GRADE system, Coleman methodology score, and Methodological Index for Non-Randomized Studies (MINORS). Heterogeneity was assessed with the I² statistic. A forest plot was used to pool the timing of bone grafting for all included studies. For data synthesis and analysis, a best evidence synthesis was used. Results: A total of 15 studies were included (353 cases). Risk of bias was high in 8 studies and the quality for 14 studies was assessed as very low, with a mean Coleman score of 33.5 and a mean MINORS score of 7.9. The mean time from the index surgery to bone grafting was 7.03 weeks ranging from 2 to 15 weeks (lower limit 6 weeks, upper limit 8.07 weeks). Best evidence analysis demonstrated that 8 of the 15 studies (53%) with 237 cases (67%) performed staged bone grafting inside this window. Union was achieved in 92%. Conclusion: The results of this best evidence systematic review suggest that, for most infected tibial non-unions, secondary bone grafting can be successfully performed between 6–8 weeks with expected union rates over 90%.