A Reliable Porcine Fascio-Cutaneous Flap Model for Vascularized Composite Allografts Bioengineering Studies

Our protocol describes the clinical re event fasciocutaneous flaps in swine. The main advantage of this technique is the reliability of the skin vascularization. The surgical technique provides a suitable tool to study vascularized composite aircraft in machine perfusion, tissue engineering, and immunology in a large animal model.

To begin, palpate the pulse of the saphenous artery, which should be approximately three finger widths medial from the patella, and tag it. Identify and draw the limits of the flap. The superior limit is an access parallel to the inguinal crease, three centimeters below it.

And the lateral limit is an axis from the anterior superior iliac spine to the medial part of the patella. Draw an oval like flap of 10 centimeter diameter, centered on the saphenous pedicle, and contained in the stated flap limits. Make an eight centimeter skin incision at the distal portion of the pedicle on the flap landmark.

Open the fascia and blunt dissect to expose the saphenous artery and its two venae comitantes. Perform a double ligature and separate it in one bundle. Incise the remaining skin of the flap with a blade.

Use cautery to open the subcutaneous tissue and the surrounding fascia. Using bipolar forceps, perform thorough hemostasis. To avoid inadvertent traction and disruption of perforating vessels, attach the skin component of the flap to the underlying fascia with three zero non-absorbable sutures.

Free the flap from the gracilis by dissecting the fascia away from the muscle. Continue the pedicle dissection by following the saphenous vessels down the femoral vessels. Perform a perpendicular incision joining the inguinal crease to the proximal part of the flap.

Make a 12 centimeter incision in the inguinal crease. Lift away the connecting skin and open the subcutaneous layer. Skeletonize the femoral vessels and legate them distally to the saphenous branch in two separate bundles.

Continue the dissection of the femoral vessels from distal to proximal until reaching the level of the inguinal ligament. Separate the femoral artery from the vein and isolate them with rubber elastics. To harvest the second saphenous flap, repeat the whole process for the contralateral hind limb.

Inject the animal with 100 units per kilogram of intravenous heparin five minutes before proceeding to the next step. Legate the femoral pedicle as proximal to the inguinal ligament as possible and separate the flap from the donor pig. Dilate the ends of the femoral vessel and insert a 20 gauge angiocatheter in both artery and vein.

Use three zero silk ties to secure the catheter to the vessels. Slowly flush the fasciocutaneous flaps artery with 10 milliliters of 100 units per milliliter heparin saline until a clear venous outflow is observed. A total of 14 saphenous fasciocutaneous flaps were harvested in this study.

The average flap procurement time was 47 minutes. The mean artery and venous diameters were 2.25 millimeters and 3.56 millimeters respectively. Finally, the mean pedicle length was 10.8 centimeters After each flap harvest, an FCF angiography was performed through intra-arterial injection of 10 millimeters of contrast product immediately after the heparin saline flush.

This step enabled the assessment of the vascularization of the skin paddle. The most important thing to remember is to perfectly attach the skin component of the flap to the underlying fascia to avoid any disruption of perforating vessels. This accurate description of reliable and reproducible flap procurement technique offers a valuable tool for VCA bioengineering studies in swine.