To study the coverage period influence and various parameters concerning the microsurgical act on the patient clinical outcomes. We report 23 cases of reconstruction of lower limb loss of substance by free flap operated from 2010 to 2021. Among them, 9 patients were operated on as an emergency versus 14 in the secondary or late phase of the trauma. The average age of injured patients operated on emergency was 42 years (17-68 years) and 34 years for the patients who undergo deferred surgery (17-57 years). The sex ratio (female/male) was 22% in patients operated on urgently and 7% in patients operated on later. Regarding the type of free flap, it was Serratus anterior muscle flap in 10 cases, Latissismus dorsi flap in 9 cases, ALT flap in 3 cases and Gracilis muscle flap in 1 case. There were 2 failures of vascularized free transfer (8.7%) with complete necrosis of the flap and 3 revision surgeries on venous thrombosis which finally made it possible to obtain 3 flap successes. We analyze the results (complications/osteitis) according to the time to coverage. In our study, we did not find any significant difference between the groups operated in emergency and at a distance concerning the rate of infection and failure of the flaps.