Objective To evaluate the effectiveness of combined anterolateral thigh-ilioinguinal Flow-through flaps for repairing complex lower extremity defects. Methods A clinical data of 20 patients with complex lower limb injuries admitted between January 2018 and January 2024 was retrospectively analyzed. The cohort included 14 males and 6 females with an average age of 47.3 years (range, 29-65 years). Injury mechanisms comprised heavy-object trauma (n=7), traffic accidents (n=5), machinery crush injuries (n=5), and osteomyelitis (n=3). Defects involved the left (n=7) and right (n=13) limbs, with anatomical distributions including tibiofibular injuries (n=6), isolated tibial injuries (n=6), foot and ankle injuries (n=5), and femoral-tibial injuries (n=3). The size of soft tissue defects ranged from 23 cm×8 cm to 44 cm×12 cm. Reconstruction employed combined anterolateral thigh-iliac inguinal Flow-through flaps in the size of 24 cm×10 cm to 48 cm×14 cm. The recipient sites were sutured in primary closure in 12 cases, and 8 cases had no available vascular anastomosis sites in the recipient area, and a cross-leg flap form was used to establish a temporary blood supply, and the flaps were cut off after 3-4 weeks. The donor sites in the thigh were directly sutured. During follow-up, the survival of the flaps, appearance, texture, and related complications were observed; the Vancouver scar scale (VSS) was used to evaluate the scar condition of the flaps, the lower extremity function score (LEFS) was used to evaluate the function of the affected lower limb, and the visual analogue scale (VAS) score was used to evaluate the pain condition of the affected side. Results Postoperatively, the flap complete necrosis occurred in 1 case, marginal necrosis in 1 case, superficial infections in 2 cases, and venous thrombosis in 1 case. The remaining flaps survived completely with primary wound healing at both recipient and donor sites. Limb salvage was achieved in all patients. All patients were followed up with 12-24 months (mean, 18.4 months). All flaps had satisfactory color, texture, and contour. Fractures reached clinical union in all cases. Donor-site morbidity included mild contralateral hip flexion/knee extension limitation (n=1), persistent hypoesthesia (n=3), and chronic pain (n=1) at 6 months. At 12 months after operation, the LEFS, VSS and VAS scores on the affected side were 62.7±4.6, 3.5±1.1, and 1.2±0.6, respectively, which were superior to those at 1 month after operation (38.6±2.8, 8.5±1.4, 4.7±1.1), and the differences were significant (P<0.05). ConclusionThe anterolateral thigh-ilioinguinal Flow-through flaps for repairing complex lower limb injuries is a good method. The distal blood supply of the affected side has recovered well, the survival rate of the flap is high, and the function recovery of the affected limb is good.