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Microsurgery 2012 Haddock

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PREDICTING PERFORATOR LOCATION ON PREOPERATIVE IMAGING FOR THE PROFUNDA ARTERY PERFORATOR FLAP

NICHOLAS T. HADDOCK, M.D., PATRICK GREANEY, M.D., DAVID OTTERBURN, M.D., STEVEN LEVINE, M.D., and ROBERT J. ALLEN, M.D.

Introduction: The profunda artery perforator (PAP) flap is a new addition to our reconstructive armamentarium. In effort to better understand patient candidacy for the PAP flap we characterized the profunda artery perforators on preoperative imaging. Methods:A retrospective review was completed of 40 preoperative posterior thigh computed tomography angiographies and magnetic resonance angiographies by four plastic surgeons. The positioning of the patient, type of study, number of perforators, and size of perforators were documented.The location was documented on an x–y-axis. Perforator course and surrounding musculature was documented. Results: In 98.8% of posterior thighs suitable profunda artery perforators were identified. The average number and size of perforators was 3.3 and 1.9 mm. The most common perforator was medial (present in 85.6% of thighs); found near the adductor magnus at 3.8 cm from midline and 5.0 cm below the gluteal fold. The second most common perforator was lateral (present in 65.4% of thighs); found near the biceps femoris and vastus lateralis at 12.0 cm from midline and 5.0 cm below the gluteal fold. Nearly 48.3% were purely septocutaneous. And 51.7% had an intramuscular course (average length 5.7 cm). Preoperative imaging corresponded to suitable perforators at the time of dissection of all PAP flaps. Thirty five PAP flaps (18 patients) were performed with 100% flap survival. Conclusion: Analysis of preoperative posterior thigh imaging confirms our intraoperative findings that a considerable number of suitable posterior thigh profunda perforators are present, emerge from the fascia in a common pattern, and are of sufficient caliber to provide adequate flap perfusion and recipient vessel size match. 2012 Wiley Periodicals, Inc. Microsurgery 00:000–000, 2012.

The reliability of perforator flaps is well documented in the literature. The popularity for perforator flaps is based on the ability to preserve underlying muscle, provide a longer pedicle length, and the ability for variability in design and location. The profunda artery perforator (PAP) flap was recently introduced as an alternative method of breast reconstruction with favorable outcomes. The PAP flap provides a sufficient area of posterior thigh skin and fat for unilateral breast reconstruction based on a single profunda artery perforator.

The posterior thigh has previously been utilized as both a myocutaneous flap and a perforator flap. Patients undergoing breast reconstruction are equally concerned about donor site cosmesis. The upper posterior thigh provides a favorable donor site with a well-hidden scar in most women. This area of skin and fat is supplied by the profunda artery via three main perforators; the first perforator supplies the adductor muscle and gracilis while the second and third perforators supply the semimembranosus, biceps femoris, and vastus lateralis.

There are multiple benefits of accurate preoperative imaging in breast reconstruction with perforator flaps. Computed tomography angiography (CTA) allows the identification of suitable perforators. This in turn provides guidance with flap choice, incision design, and avoids a potential negative exploration.

Preoperative imaging has been paramount for the early success of the PAP flap. As experience grows with this flap there are obvious patterns in perforator location,which help dictate flap design and operative approach. In effort to better describe the location of these perforators and potential patient candidacy for use of the PAP flap we reviewed the profunda artery perforators in 40 preoperative images for transverse upper gracilis (TUG), superior gluteal artery perforator (SGAP), and PAP flaps. In doing so we were able to determine which perforators are appropriate for use as a microvascular free flap, describe the perforator locations, and how many patients have suitable perforators for use of the PAP flap.

PATIENTS AND METHODS

A retrospective review was completed of 40 preoperative CTAs and magnetic resonance angiographies (MRAs) involving the upper posterior thigh. The images were reviewed by four independent plastic surgeons. All images were obtained using standard perforator protocols with the intent of using a PAP flap, SGAP flap, or a TUG flap for reconstruction of the breast.

The positioning of the patient, the type of study, and the number of perforators were documented. Patient age was documented and ranged from 38 to 55. The location was documented with the gluteal fold set as zero on the y axis and the midline set as zero on the x axis. The location in respect to the posterior thigh musculature and the perforator course was also documented. The size of all perforators was documented.

PAP Flap Procedure

Preoperative imaging helped identify skin perforators, which were confirmed by a handheld Doppler. The superior border of the flap was marked 1 cm inferior to the gluteal fold. The inferior border of the flap was marked ~7 cm below the superior marking. An elliptical flap was designed (average width of 27 cm). The patient can be positioned prone or supine with legs frog-legged. The prone position utilizes a lateral approach and maintains the theoretical possibility of conversion to a TUG flap if required while the supine position has the obvious benefit of no position change. The elliptical incision was made and dissection proceeded to the muscular fascia. Beveling in the lateral thigh increased flap volume, but should be limited superiorly to avoid disturbance of buttock contour and the gluteal fold. Dissection proceeded in a suprafascial plan until near the marked perforator and the fascia was entered. Subfascial dissection helped with perforator identification. The perforator was traced to its origin as in other perforator flaps. The donor site was closed in a multilayer fashion over a drain.

RESULTS

All images were obtained for preoperative imaging for breast reconstruction utilizing a buttock or thigh-based autologous reconstruction. Eighteen of the preoperative images were for a PAP flap, 21 were for a TUG flap, and 1 was for a SGAP flap. CTA accounted for 23 and MRA accounted for 17 of the images. Majority of patients were imaged in the supine position, 21 compared to 19 in the prone position.

Posterior thigh perforators originating from the profunda artery were consistently visualized on preoperative imaging. In 98.8% of the posterior thighs perforators with sufficient size were identified on preoperative imaging. The average number of perforators was 3.3 ± 1.2 and the average size was 1.9 ± 0.5 mm). The most common perforator location is in the medial posterior thigh, exiting the fascia in the vicinity of the adductor magnus at ~3.8 cm from midline and 5.0 cm below the gluteal fold. These perforators accounted for 49.2% of all posterior thigh perforators and were on average 1.9 ± 0.4 mm. At least one sizeable medial perforator was present in 84.6% of evaluated posterior thighs. The second most common perforator location is in the vicinity of the biceps femoris and vastus lateralis at ~12.0 cm from midline and 5.0 cm below the gluteal fold (Fig. 2). These perforators accounted for 32.5% of all posterior thigh perforators and were on average 1.9 ± 0.4 mm. At least one sizeable lateral perforator was present in 65.4% of evaluated posterior thighs. The perforators are shown mapped on an x–y coordinate and in table form.

There was one patient that had no suitable profunda artery perforators on one posterior thigh on preoperative imaging. This patient was initially scheduled to undergo a PAP flap, however was preoperatively converted to a TUG flap based on the imaging. Thirty-five PAP flaps in 18 patients were included in this series. In all cases perforators on preoperative imaging corresponded to a perforator at the time of dissection.

Intraoperatively, the course of these perforators has been found to be predominantly septocutaneous, but in some patients there was a small intramuscular component. On preoperative imaging 48.3% were purely septocutaneous. For the remaining muscular perforators (51.7%) the intramuscular course was on average 5.7 ± 2.1 cm in length.

All 35 PAP flaps (18 patients) were performed with 100% flap survival and no flap related complications. There were two donor site complications (one seroma and one small wound dehiscence). Postoperative photographs are shown of both recipient site and donor site. Those patients included in this study that underwent a TUG flap or a SGAP flap had similar results. In this series 25 TUG flaps were performed in 21 patients. Two SGAP flaps were performed in one patient.There was 100% flap survival in all TUG flaps and all SGAP flaps. There were no flap-related complications.There were three donor site complications (seromas).

DISCUSSION

The PAP flap offers an additional reconstructive option for postmastectomy patients in which no abdominal-based flap is available. While the posterior thigh profunda artery angiosome and flaps based on this angiosome have been well described the use of a transverse upper posterior thigh flap based off of these perforators is a new technique for breast reconstruction. CTA has been used to guide identification of perforators off the profunda artery allowing planning in these procedures and thus avoiding the ‘‘free-style’’ perforator dissection. While a preoperatively identified perforator on CTA or MRA does not always guarantee a suitable perforator at the time of surgical dissection, in the PAP series described here a suitable perforator was present corresponding with preoperative imaging in all cases.

The need for this flap came from the dissatisfaction with other alternative flaps (TUG, SGAP, and IGAP). Tissue obtained from the gluteal flaps lacks the same malleable characteristics of abdominal or posterior thigh tissue, restricting the surgeon’s ability to mold an aesthetic breast mound. The harvest of these flaps can also have a detrimental effect on buttock contour. A variation,utilizing a lateral septocutaneous perforator, has been described to provide increased pedicle length for gluteal flaps; however this is not always an option and still requires prone positioning. The TUG flap provides a more manageable tissue type similar to that of the PAP but sacrifices a muscle, has a short pedicle, can affect lymphatic drainage, and has an anterior scar that is visible to the patient.

On preoperative imaging for a TUG flap a posteromedial perforator off of the profunda artery was identified giving the inspiration for the first PAP flap. As experience was gained with this flap preoperative imaging was paramount to identify perforators to supply this skin paddle. Following preoperative imaging the perforators were confirmed with handheld Doppler.

To better understand the characteristics of this flap we sought to define the perforator patterns in relation to the upper posterior thigh flap. The predictability of the profunda artery perforators in the PAP flap appears to be strong on preoperative imaging. In 98.8% of posterior thighs suitable profunda artery perforators were identified on preoperative imaging. This compares favorably with other common methods of breast reconstruction.

In addition, this review provides increased documentation of the pedicle characteristics. Retrospective preoperative imaging analysis confirms our intraoperative findings that a considerable number of usable posterior profunda perforators are mainly septal in nature, while the remaining branches require some degree of muscular dissection. This is yet another advantage of this flap as compared to DIEP, SGAP, IGAP, which almost always require muscular dissection. Thus far, patients undergoing PAP breast reconstruction have very limited muscle related donor site morbidity or weakness. More patient studies are required to more closely examine the donor site morbidity of this flap.

Clinically, the average artery diameter was 2.2 mm and the average vein was 2.8 mm. Preoperative imaging often over estimates the diameter of the perforator and while we report an average diameter of 1.9 mm at the fascia this has not been found clinically. At the fascia the perforators tend to be much smaller but when dissected proximally the diameter is universally an adequate match with the internal mammary vessels. Future work should focus on perfusion studies to determine the maximum capacity of this flap when harvested on one perforator. It is possible that a zonal classification could be developed based on specific perforator choice and angiosome principles.

CONCLUSION

The PAP flap is a viable nonabdominal flap alternative for breast reconstruction. There are routinely suitable perforators for harvest of the PAP flap. These perforators are present in standards locations; medially in the vicinity of the adductor magnus and laterally in the vicinity of the biceps femoris and vastus lateralis. The initial experience with the PAP flap has been very favorable. Future work is focused on determining where this flap falls in the breast reconstruction algorithm.