Anterolateral Thigh Perforator Flap: An Ideal Pedicled Flap

The authors described the surgical anatomy of the pedicled anterolateral thigh (ALT) perforator flap, to evaluate the vascularity of the flap and to estimate its usefulness in coverinh skin and soft-tissue defects.

Eleven consecutive patients, in whom the ALT flap was used pedicled, were included in this study. Nine patients with defects in the suprapubic area, the scrotum, the circumference of the penis, the greater trochanter (2), the lateral gluteal region, the ischial tuberosity, and the lower abdominal wall (2) were treated with a proximally-based flap, and two patients with exposed knee joints with a distally-based flap. The flap size ranged from 7 × 16cm to 9 × 20cm. Skin flap perfusion was evaluated preoperatively, intraoperatively and postoperatively by measuring tissue hemoglobin oxygen saturation using Near-Infrared-Spectroscopy. The anatomy of the vascular system, the pedicle length, the pivot points and the arcs of rotation of the pedicled flaps were recorded.

Near-Infrared-Spectroscopy demonstrated in every case that initially during dissection, flap perfusion was decreased, but as the perforator's intramuscular dissection proceeded, ligating all muscular branches, hemoglobin oxygen saturation increased, and reached preoperative values postoperatively. The flap, based on a musculocutaneous perforator, was rotated either just distal to the origin of the lateral circumflex femoral artery from the profunda femoris (proximal pivot point) or just proximal to the anastomotic site of the descending branch of the lateral circumflex femoral with the lateral superior genicular artery (distal pivot point). Proximally- and distally-based ALT flaps have medial and lateral arcs of rotation, and could be rotated 180 degrees. The length of the vascular pedicle represented the radius of the arc of rotation, depending on the location of the perforator vessel and the orientation of the skin paddle, and ranged in the proximally-based flaps from 16 to 19 cm, while in the cases of distally-based flaps it was 14 cm. The proximally-based flaps, including the lateral cutaneous nerve of the thigh, were medially rotated to provide sensate skin coverage to the perineogenital area, and laterally rotated to cover the trochanteric and lateral gluteal area. The distally-based flaps, including vascularized fascia lata, were advanced forward without any rotation to cover the anterior aspect of the knee joint. All the flaps survived completely, resulting in excellent functional and aesthetic results and with minor donor- site morbidity.

The vascular system of the ALT flap permits the design of versatile pedicled flaps with tremendous vascularity and large arcs of rotation, able to cover soft-tissue defects from the lower abdominal wall to the knee joint.