Are free flaps a reliable solution to treat massive soft tissue defects in patients with knee periprosthetic joint infection? A systematic review and meta-analysis

Purpose: Large joint arthroplasty is among the most frequently performed procedures in orthopaedic surgery. One of the most common and challenging causes of prosthetic failure is periprosthetic joint infection (PJI). Periprosthetic soft tissue damage is often a critical yet underestimated factor influencing surgical outcomes. The aim of our meta-analysis is to evaluate the clinical efficacy, complications, failure rates, and the overall reliability of free flaps as a reconstructive solution. Methods: PubMed, Embase, and Google Scholar were searched, according to PRISMA guidelines. Studies were included if they reported healing rate, complications, type of free flaps, and pathogen characteristics. A quality evaluation was performed. The overall effect size was reported as survival rate of the free flaps, and the secondary effect sizes were determined as the rate of reinfection or persistent infection after coverage with free flaps and the amputation rate because of non-controlled infection. The statistical analysis was carried out using the software 'R', version 4.5.0 (2025-04-11). Results: Fourteen papers were included, with a total of 185 observations and 161 events (free flap survived). All papers were retrospective studies. The pooled survival rate was 93% (I 2 = 66.7%). The pooled rate of reinfection or persistent infection after the index surgery was 16% (I 2 = 77.6%). The amputation rate was 8%. Conclusion: Free flaps are a reliable solution to manage tissue loss in patients with periprosthetic infection, but the results could be affected by technical errors and non-skilled intra- and post-operative management. Orthoplastic and microsurgical skills are mandatory to be successful.