Analysis of multiple risk factors affecting the result of free flap transfer for necrotising soft tissue defects of the lower extremities in patients with type 2 diabetes mellitus

SummaryBackgroundThe limb-threatening large soft tissue defects that occur on the feet of type 2 diabetic patients have complex causes and are less likely to be corrected by free flap reconstruction compared to those in non-diabetic patients. We retrospectively analysed factors affecting the success of free flap transfer for necrotising soft tissue defects of the lower extremities in patients with type 2 diabetes.MethodsThis study included 33 diabetic patients whose feet were treated with free flap transfers. All patients had limb-threatening large soft tissue defects with tendon or bone exposure. The operative results were divided into three groups at 1 month post-operatively: the complete healing group, and the complication group, with either partial necrosis requiring additional simple procedures or flap failure with total necrosis. Nine preoperative factors were analysed: (1) ankle brachial index, (2) HbA1c, (3) BMI, (4) the smoking factor, (5) atherosclerotic calcifications (6) serum creatinine levels (>1.28 mg dL−1 vs. <1.28 mg dL−1), (7) GFR, (8) wound infection and (9) wound defect size.ResultsOf the 33 patients, 15 showed complete healing and 18 showed complications of the free flap (eight partial necrosis and 10 flap failure). No atherosclerotic calcifications were found in the patients in the complete healing group, although they were found in 12 patients in the complication group, and this difference was significant (p = 0.002). Patients with serum creatinine levels >1.28 mg dL−1 had significantly higher free flap transfer complication rates than those with serum creatinine levels <1.28 mg dL−1 (p = 0.038).ConclusionsThis study analysed the risk factors of free flap reconstruction for limb-threatening large soft tissue defects on the feet of type 2 diabetic patients. Serum creatinine levels >1.28 mg dL−1 and atherosclerotic calcifications were confirmed as risk factors for flap survival.