S1 Dataset -

Introduction
Salvage breast reconstruction with autologous tissue is becoming more prevalent due to a resurgence in implant-based procedures. The latter has caused a commensurate rise in failed or treatment-resistant prosthetic cases requiring conversion to free tissue transfers. Salvage reconstruction is often considered more challenging, owing to patient presentation, prior treatments and intraoperative difficulties. The aim of the study was to test this hypothesis by comparing outcomes of salvage versus non-salvage autologous microsurgical breast reconstructions in a retrospective matched cohort study.
Methods
The demographics, risk factors, operative details and outcomes of patients who underwent free flap salvage of implant-based reconstructions by a single operator (2005–2019) were retrospectively evaluated. For each salvage reconstruction, the consecutive non-salvage abdominal free flap reconstruction was selected for comparison. The clinical outcomes including intraoperative blood loss, operative time, flap survival and complication rates were compared.
Results
Of 442 microsurgical patients, 35 (8.0%) had salvage reconstruction comprising 41 flap transfers (29 unilateral, 6 bilateral) and 42 flaps (28 unilateral, 7 bilateral) in nonsalvage reconstruction. Deep inferior epigastric perforator (DIEP) flaps comprised the commonest autologous tissue used in both groups at 74% and 71% respectively. Most patients (83%) underwent salvage reconstruction for severe capsular contractures. There was a significant difference in radiation exposure between groups (salvage reconstruction 89%, non-salvage reconstruction 26%; p<0.00001). All 83 flaps were successful with similar reoperation rates and intraoperative blood losses. Unilateral salvage reconstruction took on average two hours longer than non-salvage reconstruction (p = 0.008). Overall complication rates were similar (p>0.05).
Conclusion
This 15-year study shows that despite salvage autologous free flap breast reconstruction requiring longer operation times, its intra and postoperative outcomes are generally comparable to non-salvage cases. Therefore, salvage breast reconstruction with free flaps provides a reliable option for failed or suboptimal implant-based reconstructions.