A prospective study of super-thin anterolateral thigh flap harvesting assisted by high-frequency color Doppler ultrasound in detecting perforators in deep adipose layers

Abstract

To investigate the clinical application of high-frequency color Doppler ultrasound (HFCDU) in detecting perforators in the deep adipose layers for harvesting super-thin anterolateral thigh flap (ALTF). Between August 2019 and January 2023, 45 patients (46 sides) with skin and soft tissue defects in the foot and ankle were treated, including 29 males and 16 females, aged from 22 to 62 years, with an average of 46.7 years. The body mass index ranged from 19.6 to 36.2 kg/m 2, with an average of 23.62 kg/m 2. The causes of injury included traffic accident injury in 15 cases, heavy object crush injury in 20 cases, mechanical injury in 8 cases, heat crush injury in 1 case, and chronic infection in 1 case. There were 20 cases on the left side, 24 cases on the right side, and 1 case on both sides. After thorough debridement, the wound size ranged from 5 cm×4 cm to 17 cm×11 cm. All patients underwent free super-thin ALTF transplantation repair. HFCDU was used to detect the location of the perforators piercing the deep and superficial fascia, as well as the direction and branches of the perforators within the deep adipose layers before operation. According to the preoperative HFCDU findings, the dimensions of the super-thin ALTF ranged from 6 cm×4 cm to 18 cm×12 cm. The donor sites of the flaps were directly sutured. A total of 55 perforators were detected by HFCDU before operation, but 1 was not found during operation. During operation, a total of 56 perforators were found, and 2 perforators were not detected by HFCDU. The positive predictive value of HFCDU for identifying perforator vessels was 98.2%, and the sensitivity was 96.4%. Among the 54 perforators accurately located by HFCDU, the orientation of the perforators in the deep adipose layers was confirmed during operation. There were 21 perforators (38.9%) traveled laterally and inferiorly, 12 (22.2%) traveled medially and inferiorly, 14 (25.9%) traveled laterally and superiorly, 5 (9.3%) traveled medially and superiorly, and 2 (3.7%) ran almost vertically to the body surface. Among the 54 perforators accurately located by HFCDU, 35 were identified as type 1 perforators and 12 as type 2 perforators (HFCDU misidentified 7 type 2 perforators as type 1 perforators). The sensitivity of HFCDU in identifying type 1 perforators was 100%, with a positive predictive value of 83.3%. For type 2 perforators, the sensitivity was 63.2%, and the positive predictive value was 100%. The surgeries were successfully completed. The super-thin ALTF had a thickness ranging from 2 to 6 mm, with an average of 3.56 mm. All super-thin ALTF survived, however, 1 flap experienced a venous crisis at 1 day after operation, but it survived after emergency exploration and re-anastomosis of the veins; 1 flap developed venous crisis at 3 days after operation but survived after bleeding with several small incisions; 3 flaps had necrosis at the distal edge of the epidermis, which healed after undergoing dressing changes. All 45 patients were followed up 6-18 months (mean, 13.6 months). Three flaps required secondary defatting procedures, while the rest had the appropriate thickness, and the overall appearance was satisfactory. Preoperative application of HFCDU to detect the perforator in the deep adipose layers can improve the success and safety of the procedure by facilitating the harvest of super-thin ALTF.