BackgroundFlow-through flaps have been widely applied only for the reconstruction of complex defects in the extremities because they can be used for arterial reconstruction and soft tissue coverage simultaneously. This report attempts to fully demonstrate the role of the anterolateral thigh (ALT) flow-through flap as a versatile method for reconstructing complex defects in the extremities. MethodsFrom February 2011 to March 2017, we retrospectively analyzed the use of a reconstructive surgical technique based on the ALT flow-through flap to treat complex extremity defects in 87 patients (trauma, n = 79; diabetic ulcers, n = 5; squamous cell carcinoma, n = 3). Emergency surgery was performed in 12 patients to bridge a major artery gap and was followed by elective reconstruction in the remaining patients. Applications of the ALT flow-through flap included bridging major artery gaps, preserving recipient blood vessel integrity, reconstructing blood vessel continuity, protecting vascular anastomoses, avoiding difficult end-to-side anastomoses in the recipient area, and balancing blood flow, as well as combined application with an additional flap. ResultsThe flap size ranged from 6 x 3 cm to 17 x 9 cm. ALT flow-through flaps were used in combination with an additional flap (n = 4) and in vascular reconstruction (n = 83). Three patients required of the microvascular anastomostic reexploration for venous congestion, total necrosis occurred in two patients, and partial necrosis occurred in one patient. At the donor site, there were three cases of infection and two cases of wound dehiscence. At the recipient site, one case of infection and two cases of wound dehiscence were observed. One patient presented with deep infection secondary to renal failure and underwent amputation. During the follow-up period (range, 1-33 months), all other flaps (84 cases) survived uneventfully, with normal texture and color. ConclusionThe ALT flow-through flap plays many roles as it is a versatile method for reconstructing complex defects of the extremities and serves various other clinical purposes.