Immediate Versus Delayed Skin Grafting of Free Muscle Flaps for Limb Salvage: Does Timing Matter?

Abstract

Lower extremity (LE) muscle free flaps (MFF) require split-thickness skin grafts (STSG) for coverage. Medically comorbid patients undergoing MFFs have demonstrated surprisingly high rates of skin graft failure over the MFF. This study therefore characterizes the risks for STSG failure and the effect of staging STSG on graft outcomes in medically comorbid patients. A retrospective review of patients undergoing STSG for LE MFF coverage between 2011 and 2023 was performed. Demographics, comorbidities, MFF details, STSG details, and complications were collected. The primary outcome was graft failure. Ninety-one patients underwent MFF and STSG, with 65 (71.4%) undergoing immediate STSG and 26 (28.6%) undergoing delayed STSG, at a median of 12 days (IQR = 9) after MFF. The delayed group had a significantly higher Charlson Comorbidity Index (5.6 vs. 3.7, p < 0.001). The overall graft failure rate was 31.5%, with no differences between groups (immediate: 27% vs. delayed: 42.3%, p = 0.157). On multivariable analysis, elevated preoperative HbA1c (OR: 1.5, CI = 1.1-1.9), low levels of albumin preoperatively (OR: 0.3, CI: 0.1-0.9), and a history of Charcot arthropathy (OR: 8.6, CI: 1.3-55.2) were independent predictors of graft failure. Little evidence exists to help guide the decision to perform immediate versus delayed skin grafting of MFFs in a highly comorbid population undergoing limb salvage. Delaying skin grafts in patients with significant comorbidities that threaten flap viability and wound healing capacity may improve graft take. Patient comorbidities, nutritional status, and intraoperative factors should also be considered when determining the timing of skin grafts over MFF.