Re‐Evaluation of the Ideal Injury to Flap Time Frame for Lower Extremity Free Flap Reconstruction: Is 72 h Still the Gold Standard?

BACKGROUND: Traumatic lower extremity injuries often require free tissue transfer (FTT) for limb salvage when local tissue is insufficient. Traditionally, reconstruction within 72 h has been considered optimal; however, advancements in wound management and perioperative care have challenged this paradigm. OBJECTIVE: To evaluate outcomes of lower extremity FTT based on time from injury to reconstruction. METHODS: A retrospective review was performed on patients undergoing lower extremity FTT after trauma at a single Level 1 trauma center (2014-2022). Patients were grouped by time from injury to flap: (< 3 days, 4-21 days, 22-90 days, and > 90 days). Ninety nine percent of patients were managed with negative-pressure wound therapy (NPWT) prior to definitive reconstruction. Outcomes included flap loss, complications, infection, osteomyelitis, nonunion, and amputation. Associations with comorbidities, surgical techniques, and fracture characteristics were assessed. RESULTS: Among 102 patients, timing of reconstruction showed no significant differences in flap loss (p = 0.56), complications (p = 0.42), nonunion (p = 0.54), osteomyelitis (p = 0.19), or amputation (p = 0.58). No independent predictors of flap loss or complications were identified. Nonunion was associated with middle/proximal fracture levels (p = 0.0092), Masquelet technique (p = 0.0004), and higher Modified Frailty Index (p = 0.05). Osteomyelitis correlated with male gender (p = 0.01), proximal fracture level (p = 0.0098), and Masquelet technique (p = 0.0095). Amputation was associated with latissimus and radial forearm flaps (p = 0.0081), ipsilateral femur fracture (p = 0.0063), hypertension (p = 0.011), and higher ASA score (p = 0.0021). CONCLUSION: In this series, delayed FTT beyond 72 h was not associated with increased flap loss or limb-threatening complications. Delayed reconstruction may optimize patient and wound factors, though aggressive wound management is essential. Given the retrospective design, uneven group sizes, and small early reconstruction cohort, these findings should be interpreted cautiously. Further research with larger cohorts and long-term outcomes is warranted.