Does preoperative wound infection impact outcomes of lower extremity salvage via microvascular free flap reconstruction? A cohort study

Abstract

We sought to identify preoperative wound characteristics associated with a higher risk of adverse outcomes in patients undergoing lower extremity (LE) reconstruction with microvascular free flaps. A retrospective review of patients undergoing free flap reconstruction of the LE at a single academic institution between 2010-2021 was conducted. Preoperative wound culture results were classified by Gram stain, aerobe status, multi-drug resistance (MDR), and presence of multiple bacteria. Outcomes studied included flap viability at 60, 120, and 180 days, as well as flap dehiscence, partial and full necrosis, sepsis, and amputation. A total of 218 LE free flap reconstructions were performed during the study period. 152 (69.7%) of patients were male. Rate of secondary amputation following attempted limb salvage was 4.6%. LE reconstructions utilized either fasciocutaneous (79.4%) or muscular flaps (20.6%). The type of free flap used for reconstruction had no effect on reconstructive outcomes or flap viability. Preoperative bacterial wound cultures were obtained in 102 (46.8%) patients; 80 cultures (78.4%) were positive for bacterial growth. Of these, 33 (41.2%) grew Gram-positive bacteria, 14 (17.5%) grew Gram-negative bacteria, and 33 (41.2%) grew multiple organisms. Positive preoperative wound culture was independently associated with flap failure at 120 days ( p = 0.04) when compared to wounds with no infection. Among patients with positive cultures, polymicrobial infection was significantly associated with higher rates of amputation ( p = 0.04) compared to single Gram-positive or Gram-negative infectious agents. Identification and management of positive wound cultures may play an important role in outcomes of microvascular free flap reconstruction. • Positive preoperative wound culture is associated with free flap failure at 120 days. • Positive wound culture is not associated with flap dehiscence or necrosis. • Polymicrobial infection was associated with higher rates of amputation.