Traumatic limb salvage with free flap reconstruction versus primary amputation for lower extremity (LE) injuries remains an oft debated topic. Limb salvage has well-studied benefits and advances in microsurgery have helped reduce the complication rates. A subset of patients eventually requires secondary amputation after a failed attempt at limb salvage. A better understanding of risk factors that predict subsequent amputation after failed free flap reconstruction of LE injuries may improve operative management.
 A retrospective study (2002-2019) was conducted on all patients who underwent free flap reconstruction of the LE within 120 days of the original inciting event at a single institution. Patient and operative factors were reviewed including comorbidities, severity of the injury, flap choice, outcomes, and complications. Predictors of subsequent amputation were analyzed.
 A total of 129 patients requiring free flap reconstructions for LE limb salvage met inclusion criteria. Anterolateral thigh flaps (70.5%) were performed most frequently. Secondary amputation occurred in 10 (7.8%) patients. Preoperative factors associated with eventual amputation include diabetes mellitus ( = 0.044), number of preoperative debridements ( = 0.013), evidence of any arterial injury/pathology ( = 0.008), specifically posterior tibial artery ( = < 0.0001), and degree of three-vessel runoff ( = 0.007). Operative factors associated with subsequent amputation include evidence of recipient artery injury/pathology ( = 0.008). Postoperative factors associated with secondary amputation include total flap failure ( = 0.001), partial flap failure ( = 0.002), minor complications ( = 0.037), and residual osteomyelitis ( = 0.028).
 Many factors contribute to the reconstructive surgical team’s decision to proceed with limb salvage or perform primary amputation. Several variables are associated with failed limb salvage resulting in secondary amputation. Further studies are required to better guide management during the limb salvage process.

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