Corrine Wong

The perforasome theory: vascular anatomy and clinical implications.

Background: A clear understanding of the vascular anatomy of an individual perforator relative to its vascular territory and flow characteristics is essential for both flap design and harvest. The authors investigated the three-dimensional and four-dimensional arterial vascular territory of a single perforator, termed a “perforasome,” in major clinically relevant areas of the body. Methods: A vascular anatomy study was performed using 40 fresh cadavers. A total of 217 flaps and arterial perforasomes were studied. Dissection of all perforators was performed under loupe magnification. Perforator flaps on the anterior trunk, posterior trunk, and extremities were studied. Flaps underwent both static (three-dimensional) and dynamic (four-dimensional) computed tomographic angiography to better assess vascular anatomy, flow characteristics, and the contribution of both the subdermal plexus and fascia to flap perfusion. Results: The perfusion and vascular territory of perforators is highly complex and variable. Each perforasome is linked with adjacent perforasomes by means of two main mechanisms that include both direct and indirect linking vessels. Vascular axis follows the axiality of linking vessels. Mass vascularity of a perforator found adjacent to an articulation is directed away from that same articulation, whereas perforators found at a midpoint between two articulations, or midpoint in the trunk, have a multidirectional flow distribution. Conclusions: Each perforator holds a unique vascular territory (perforasome). Perforator vascular supply is highly complex and follows some common guidelines. Direct and indirect linking vessels play a critical part in perforator flap perfusion, and every clinically significant perforator has the potential to become either a pedicle or free perforator flap.

AlloDerm versus dermamatrix in immediate expander-based breast reconstruction: A preliminary comparison of complication profiles and material compliance

Background: Allogenic acellular dermal matrix can be used in single-stage, expander-based immediate and delayed breast reconstructions to provide inferolateral prosthesis coverage and reconstruction of the inframammary fold. Two allogenic dermal matrix products currently available, AlloDerm and DermaMatrix, differ in method of storage, cost, and intraoperative preparation. The purpose of this study was to determine, first, whether there are any significant differences in the rates of postoperative complications, material compliance, or capsule characteristics; and second, if differences are present, whether they had any impact on final outcome. Methods: After institutional review board approval, a retrospective analysis of prospectively collected data of 30 patients (50 breasts) who underwent immediate expander-based breast reconstructions using either AlloDerm (n = 25) or DermaMatrix (n = 25) dermal substitutes was performed. Primary endpoints were (1) incidence of seroma, (2) wound infection, (3) number of days requiring drains, (4) rate of tissue expansion, (5) final expanded volume, (6) final implant volume, and (7) neovascularization. Results: The mean follow-up was 6.7 months. During this time, no significant differences in the complication profile were found between the two groups. Both dermal substitutes were found to be well incorporated, with evidence of neovascularization, on histologic examination. Conclusions: This study demonstrated no significant differences in the rate of complications or material compliance. The total complication rate was 4 percent, with seroma and wound infection being the most common complications. The authors’ preliminary findings indicate no significant difference between implant/expander-based reconstructions using AlloDerm and those using DermaMatrix.

The anatomy of suborbicularis fat: Implications for periorbital rejuvenation

Background: Periorbital rejuvenation has increasingly relied on augmentation with fillers. Numerous techniques have been described, including augmentation of the sub–orbicularis oculi fat. Cadaver studies initiated 2 years ago yielded presumptive evidence that sub–orbicularis oculi fat consists of two distinct regions. Knowledge of this anatomy is important for precision in facial rejuvenation. Methods: A pilot study was performed with radiopaque dye injection into the sub–orbicularis oculi fat and computed tomographic evaluation with three-dimensional reconstruction. Eight hemifacial fresh cadaver dissections were then performed with a modified dye injection technique to isolate regions of sub–orbicularis oculi fat and periorbital fat. The relationship of suborbicularis fat to deep cheek fat was observed. Results: This study confirms the presence of two distinct regions of sub–orbicularis oculi fat. A medial component extends along the orbital rim from the medial limbus to the lateral canthus. A lateral component extends from the lateral canthus to the temporal fat pad. The lateral component terminated superiorly at the lateral orbital thickening. Deep cheek fat abutted the medial sub–orbicularis oculi fat, thus creating a deep fat system in continuity across the face of the maxilla and along the orbital rim. Conclusions: This anatomy helps to define midface adipose tissue as a system of superficial and deep fat, of which medial and lateral sub–orbicularis oculi fat are a part. A working hypothesis of facial aging continues with the concept that loss and/or ptosis of deep fat compartments leads to changes in shape and contour. Folds, in contrast, occur at transition points between thick and thinner superficial fat compartments. These anatomical observations further the goal of site-specific augmentation and facial rejuvenation.

Freestyle pedicle perforator flaps: clinical results and vascular anatomy.

Background: Perforator flaps have increased in use, with advantages such as sparing of the underlying muscle with resultant decreased donor-site morbidity and the possibility of improving aesthetic outcome. Theoretically, a flap can be based on any perforator, whether free or pedicled, based on the perforasome theory. In this study, the principle of free-style perforator flaps was used to harvest pedicled flaps. Methods: The authors report the cumulative experience with freestyle perforator flaps of two medical centers (Hôpital Maisonneuve-Rosemont and University of Texas Southwestern Medical Center). Fifty-three pedicled perforator flaps were performed on 49 patients for local reconstruction of a range of defects at various anatomical locations: head and neck (n = 3), anterior trunk (n = 13), posterior trunk (n = 9), perineal/gluteal (n = 4), lower limb (n = 20), and upper limb (n = 4). Results: Complete flap survival was obtained in 48 of 53 flaps. Complications included three cases of partial flap necrosis and two total flap failures, the latter in high-risk patients. Complete primary closure of the donor site was possible in 37 cases, especially in the trunk. Twelve patients had partial primary closure complemented by skin grafting, three cases required complete skin grafting, and one donor site required another local flap for closure. Five clinical examples are given—anterior trunk, posterior trunk, cervical region, lower limb, and upper limb. Conclusions: This is a large series on clinical applications of the freestyle pedicled perforator flap. Because of its many advantages and its versatility, the authors believe it will find its place as a valued reconstructive option and, when indicated, a simpler alternative to free flaps.

The radial artery pedicle perforator flap: Vascular analysis and clinical implications

BACKGROUND The purpose of this study was to determine the location, size, and vascular territory of the radial artery cutaneous perforators. METHODS Twenty-six human cadaveric forearms were dissected. All cutaneous radial artery perforators were analyzed for total number, orientation, location, and external diameter. A cluster analysis was performed to determine the overall distribution of perforators. The cutaneous territory of a distally based pedicled perforator flap was determined using methylene blue injection and three-dimensional computed tomographic angiography in five flaps. RESULTS Six hundred thirty-nine perforators (399 perforators smaller than 0.5 mm compared with 240 perforators 0.5 mm or larger) were dissected in 26 forearms. Of the 639 radial artery perforators dissected, 328 (51 percent) were radially distributed and 311 (49 percent) were ulnarly distributed. There are two main clusters of clinically relevant perforators at a relative distance of 17.6 percent and 61.7 percent along the radial styloid-to-lateral epicondyle interval. In all cases, two or more perforators were found within 2 cm proximal to the styloid. Dye injection of the most dominant distally based perforators revealed a cutaneous territory ranging from 104 cm2 to 333 cm2. The case presented is of a patient with a dorsal hand defect, which was resurfaced with a pedicled perforator flap based on a distal perforator proximal to the radial styloid. CONCLUSIONS There are two main clusters of clinically significant radial artery perforators. Increased knowledge of size, location, and cutaneous territory of the radial artery perforators can lead to expanded use of the radial artery forearmflap based on cutaneous perforators alone, without sacrificing the radial artery.

The single dominant medial row perforator DIEP flap in breast reconstruction: three-dimensional perforasome and clinical results.

Background: Successful outcomes with the deep inferior epigastric artery perforator (DIEP) flap are heavily dependent on identifying the largest perforators. The purpose of this study was to describe the vascular anatomy (location, size, zones of perfusion, and variations) of the single most dominant deep inferior epigastric artery perforator and to report a clinical series based on this flap. Methods: Eleven abdominal flaps were harvested from fresh adult cadavers, and measurements were combined with clinical measurements from 16 patients. Details such as perforator size, location, type, and zones of perfusion were documented for all flaps and clinical outcomes for all patients. Results: A total of 36 flaps were dissected with an average perforator location within a 3-cm radius of the umbilicus and an average perforator size greater than 1.8 mm. Computed tomographic scans of the cadaver abdominal flaps demonstrated consistent perfusion in zones I and II and half of zones III and IV. Clinical results showed partial flap necrosis in one patient and fat necrosis of less than 5 percent in three patients, all of which occurred in the distal portion of zone III. The deep inferior epigastric artery medial row perforators near the umbilicus were found to be the largest perforators in the entire deep inferior epigastric artery system and abdomen. Conclusions: The single dominant medial row perforator has a maximal vascularity in zones I and II, and less in zones III an IV. The authors recommend that half of zone III and all of zone IV be discarded to avoid the risks of partial flap loss and fat necrosis.

Three- and four-dimensional computed tomography angiographic studies of commonly used abdominal flaps in breast reconstruction.

Background: The innovative technique of three- and four-dimensional computed tomographic angiography allows us to analyze the areas of perfusion in commonly used free abdominal flaps in breast reconstruction, such as pedicled transverse rectus abdominis musculocutaneous (TRAM) flaps, full TRAMs, muscle-sparing TRAMs, and deep inferior epigastric perforator (DIEP) flaps. The authors compared the vascular territories in these flaps. Methods: A total of 11 lower abdominal flaps were obtained from nine cadavers and two abdominoplasty procedures. The authors simulated the perfusion of seven pedicled TRAMs, eight full TRAMs, eight muscle-sparing TRAMs, 14 DIEPs, and six superficial inferior epigastric artery flaps. For each simulated flap, the named artery/perforator was injected with Omnipaque contrast using a Harvard precision pump at 0.5 ml/minute, and the flap was subjected to dynamic computed tomographic scanning using a GE Lightspeed 16-slice scanner. Scans were repeated at 0.125-ml increments (every 15 seconds) for the first 1 ml, then at 0.5-ml increments (every 60 seconds) for the next 2 to 3 ml, thus giving progressive computed tomographic images over time. Images were viewed using both General Electrics and TeraRecon systems, allowing analysis of branching patterns and perfusion flow as well as measurements of vascular territory. Conclusions: This study shows that there are definitive differences in vascular territory based on flap type. The sequences of images also allow us to reappraise the classic Hartrampf zones of perfusion.

The Extended Anterolateral Thigh Flap: Anatomical Basis and Clinical Experience

Background: Reports suggest that the anterolateral thigh flap can be reliably extended to include adjacent vascular territories. The vascular basis of this phenomenon is poorly understood. This study examines the three- and four-dimensional arterial and venous anatomy of the extended anterolateral thigh flap and reports the results of a clinical series of extended anterolateral thigh flaps. Methods: Fifteen anterior hemithigh specimens harvested from fresh cadavers from the Western population were studied. Four-dimensional computed tomographic angiography was used to investigate the arterial and venous anatomy and pattern of perfusion. Injection of perforators within the lateral femoral circumflex femoral vascular territory, and those of the common femoral and superficial femoral arteries, was performed to investigate the vascular connections within the extended anterolateral thigh flap. Static three-dimensional imaging and latex dissections were also performed to confirm the results. A clinical series of 12 consecutive patients is also reported in which extended anterolateral thigh flaps were used for posttrauma or postoncologic reconstruction. Results: Large-diameter linking vessels at the suprafascial level enabled perfusion of the adjacent common femoral and superficial femoral artery vascular territories. In the clinical series, the flap cutaneous territory ranged from 250 to 630 cm2 (mean, 365 cm2), with all flaps except one perfused by a single perforator. No partial or complete flap losses occurred. Conclusions: This study reports the vascular basis and clinical safety of the extended anterolateral thigh flap, which can be harvested if the linking vessels between adjacent vascular territories in the anterior thigh are preserved. The extended flap is reliably perfused by a single dominant perforator.

The pedicled descending branch muscle-sparing latissimus dorsi flap for breast reconstruction.

Background: The pedicled descending branch muscle-sparing latissimus dorsi flap with a transversely oriented skin paddle presents distinct advantages in breast reconstruction, including reduced donor-site morbidity and greater freedom of orientation of the skin paddle. This study reports the anatomical basis, surgical technique, complications, and aesthetic and functional outcomes following use of this flap for breast reconstruction. Methods: A retrospective study of 20 patients who underwent breast reconstruction with a pedicled muscle-sparing latissimus dorsi musculocutaneous flap was conducted. Indications for surgery included breast reconstruction following mastectomy, lumpectomy, and irradiation, and for correction of implant-related complications. Case-note review was performed, as was a functional evaluation consisting of a patient questionnaire, a Disabilities of the Arm, Shoulder, and Hand form, postoperative range-of-motion analysis, and instrumented strength testing comparing the operated and nonoperated sides. Aesthetic evaluation of the donor site was conducted by all patients. An anatomical study of 15 flaps harvested from fresh cadavers was performed to determine the location of the bifurcation of the thoracodorsal artery and the course of its descending branch. Results: Twenty-four descending branch muscle-sparing latissimus dorsi flaps were harvested. All donor sites were closed primarily, with skin paddle sizes ranging up to 25 × 12 cm. There was one case of minor flap tip necrosis and no instances of seroma. There was no statistically significant difference in strength or range of motion of the shoulder joint when comparing the operated to the nonoperated side. Two patients reported minor functional impact following surgery. Conclusions: The pedicled descending branch muscle-sparing latissimus dorsi flap with a transversely orientated skin paddle results in minimal functional deficit of the donor site, absence of seroma, large freedom of orientation of the skin paddle, low rate of flap complications, and a cosmetically acceptable scar.

Three- and Four-Dimensional Arterial and Venous Perforasomes of the Internal Mammary Artery Perforator Flap

Background: The internal mammary artery perforator flap has been used in head and neck reconstruction. Although anatomical and perfusion studies with ink have been performed previously, the authors now use three- and four-dimensional computed tomographic angiography to precisely visualize vascular anatomy of individual perforators (perforasomes) and the axiality of perfusion. Methods: Eleven hemichest adipocutaneous flaps were dissected from cadavers. Measurements were recorded, such as the distance of each internal mammary artery perforator from the sternal edge, diameter of vessels, and number and location of internal mammary artery perforators per hemichest. Single internal mammary artery perforator injections with Isovue contrast were carried out, and the flaps were subjected to dynamic computed tomographic scanning. Static computed tomographic scanning was also undertaken using a barium-gelatin mixture. Images were viewed using both General Electric and TeraRecon systems, allowing the appreciation of vascular territory (three-dimensional), and analysis of perfusion flow (four-dimensional). Results: Each hemichest flap had one to three internal mammary artery perforators, most commonly in intercostal spaces 1, 2, and 3. Twenty-six internal mammary artery perforators were dissected, and 19 perforator arteries and six perforator veins were injected with contrast. The internal mammary artery perforator in the second intercostal space had the largest mean diameter and a large vascular territory. Linking vessels, both direct and indirect, communicate between perforators and can enlarge perforasomes. Linking vessels were also found between internal mammary artery perforators and the lateral thoracic artery. Conclusions: Three- and four-dimensional computed tomographic angiography allows detailed analysis of vascular anatomy. Important information such as internal mammary artery perforator flap dimensions, linking vessels, and axiality of perfusion is elucidated, thus contributing to a better understanding of perforator flaps.