Defining vascular supply and territory of thinned perforator flaps: Part II. Superior gluteal artery perforator flap.

Background: Superior gluteal artery perforator flaps are surgical options in breast and pressure sore reconstructions. Based on the recipient site, primary thinning of these flaps may be necessary for final optimal contour. As the thinning of a superior gluteal artery perforator flap should be based on the knowledge of perforator vascular territories to prevent vascular compromise, the authors performed an anatomical study to determine the number, location, and diameter of the perforators present in the superior gluteal artery perforator flap. Accompanying veins and acceptable locations for surgical incisions were also determined.

Methods: Fourteen superior gluteal artery perforator flaps were harvested from seven cadavers. Perforator flaps were thinned to 8 to 15 mm, except for a 2.5-cm radius around the dissected perforator. Vascular territory areas were quantified before and after thinning by photographic and radiographic methods, and respective vascular territory maps were constructed. Surgical incision "danger zones" of vertical and horizontal axes were determined at specific depths (relative to the skin surface) for each flap. Danger zone measurements were determined with an automatic three-dimensional vascular tree construction using computed tomographic images and several modeling algorithms.

Results: Mean perforator artery diameter and number at the fascia level were 0.91 +/- 0.07 mm and 2.86 +/- 0.77 (mean +/- SD), respectively. Perforator pedicles were located midway between the posterior superior iliac spine and the greater trochanter. After thinning, skin surface and whole flap vascular territories were reduced 80.9 percent (photographic) and 76.9 percent (radiographic), respectively, compared with unthinned vascular territory areas. From the skin at 4-, 6-, and 8-mm thicknesses, elliptical danger zones (two vertical segments and two horizontal segments) had overall vertical segment axis length ranges from the pedicles of 59 to 66 mm, 51 to 57 mm, and 49 to 51 mm, respectively. Horizontal axis segment length ranges were 61 to 76 mm, 61 to 66 mm, and 60 to 57 mm for 4-, 6-, and 8-mm skin thicknesses, respectively.

Conclusions: The superior gluteal artery perforator flap provides an excellent blood supply to adipose tissue but may be compromised when aggressively thinned. Surgeons may design and harvest partially thinned superior gluteal artery perforator flaps based on the anatomical vascular territory maps provided by this study.