To investigate the clinical effects of retrograde anterolateral thigh perferator flaps assisted with CT angiography (CTA) in repairing skin and soft tissue defects around the knee or in proxiamal lower leg. A retrospective cohort study was conducted. From May 2015 to October 2019, 17 patients with skin and soft tissue defects around the knee or in proximal lower leg were admitted to Department of orthopedics of Jizhong Energy Xingtai Mig General Hospital, including 12 males and 5 females, aged 16-65 years, with an average age of 35 years. The areas of skin and soft tissue defects after debridement ranged from 6.0 cm×3.0 cm to 15.0 cm×9.0 cm. The retrograde anterolateral thigh perferator flaps were designed according to the origin of the perforating branches in flaps and the length of the vascular pedicle examined with CTA and the condition of the wound to repair the wounds. The descending branches of lateral circumflex femoral artery of flaps were anastomosed with veins around the wounds. The areas of resected flaps ranged from 6.5 cm×3.5 cm to 15.5 cm×9.5 cm. The wounds in donor sites of flaps were sutured directly or covered with medium-thickness skin grafts from contralateral upper leg. The sources of lateral circumflex femoral artery and the relative length of the vascular pedicle were compared between preoperative CTA and intraoperative observation. The survivals of the flaps were observed. At the last follow-up, the effects of flaps in repairing wounds were evaluated; the motion ranges of flexion and extension of the knee joint were measured, and the knee joint function was evaluated according to the Hohl knee joint function evaluation standard; the sensory function in the flap area was evaluated according to the sensory function evaluation standard formulated by the British Medical Research Council the occurrence of complication affecting motor function of flap donor sites was observed. Data were statistically analyzed with paired sample test. The perforating brances in flaps were originated from descending branches, oblique branches, and rectus femoris branches of lateral circumflex femoral artery in 7, 6, and 4 patients, respectively. The preoperative CTA examination of lateral circumflex femoral artery was consistent with those observed during operation. The relative lengths of vascular pedicles of type 1, 2, and 3 flaps calculated after CTA examination were 0.32±0.13, 0.56±0.07, and 0.56±O.15, which were closed to 0.35±0.12, 0.52±0.10, and 0.53±0.12 measured and calculated during operation, respectively (=0.45, 0.80, 0.31, ＞0.05).All flaps survived in 17 cases without vascular crisis. At the last follow-up, 16 cases were satisfied with effects of flaps in repairing wounds, and satisfaction of the other 1 case for the repairing effcts was general; the flexion range of knee joint was 100-120°, and the extension range of knee joint was -2-0°; knee joint function was evaluated as excellent in 9 cases, good in 7 cases, and poor in 1 case; the sensory function of the flap area reached S level in 2 cases, S level in 8 cases, and S level in 7 cases; there was no adverse effect in motor function of the donor sites of flaps. Retrograde anterolateral thigh perferator flap is an effective method for repairing skin and soft tissue defects around the knee or in proximal lower leg. Preoperative CTA examination can fully show the anatomical characteristics of the branches of the lateral circumflex femoral artery and the perforating vessels of each branch, which can guide flap design and operation, thus shortening operation time and improving flap survival rate, with good clinical effects.

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