Flap prefabrication using an exteriorised vascular pedicle in a rabbit ear model

Reduction of Morbidity With a Reverse-Flow Sural Flap: A Two-Stage Technique

The reverse sural flap has often been used for cutaneous coverage of the distal region of the leg and ankle. When the flap is performed in 2 stages, the vascular pedicle is exteriorized and later resected. Our goal was to assess the reverse sural flap performed in 2 stages regarding its viability and low morbidity along the flap-donor area. Eleven patients with cutaneous coverage loss found in the area between the distal third of the leg and ankle underwent cutaneous coverage surgery with a reverse-flow sural flap with an exteriorized pedicle, without violation of the skin between the base of the flap pedicle to the margin of the wound. After a minimum period of 15 days with flap autonomy, the pedicle was resected. The flap dimensions, its viability before and after the pedicle ligature, and the distance from the intact skin between the flap base and the margin of the wound were evaluated. Any losses were measured as a percentage of the total flap size. The respective length and width of the flap were a mean average of 7.45 cm × 4.18 cm. All the flaps survived. Partial loss of the flap occurred in 3 patients, ranging from 20% to 30%. The mean average distance of the intact skin between the pedicle base and the margin of the wound was 5.59 (range 4 to 8) cm. Our results showed that the 2-stage reverse sural flap ensures good flap survival and low morbidity.

Plastische Deckung von Weichteildefekten im Gesicht

The difficulties in facial reconstruction derive from the unique character of the face and the availability of local matching tissues. Facial reconstructive surgery must aim at a functionally and aesthetically rehabilitated patient. The performance of facial plastic surgery requires an understanding and the application of many important principles. The aim of this paper is to review the critical factors to be considered in the management of surgical wounds by second-intention healing, primary closure, skin grafting, and repair with local or distant free flaps. The key concepts useful in flap choice and implementation are discussed. In addition, an overview of new developments in tissue engineering and gene therapy as they relate to facial plastic surgery is provided.

[Principles and possibilities of reconstruction with microsurgical flaps]

Microsurgical reconstructions are considered an integral art of modern reconstructive concepts, especially in the fields of trauma, tumor reconstruction, and correction of congenital deformities. Patient expectations regarding function and aesthetics of plastic surgical reconstructions are satisfied with permanently improved flap designs that also lead to a significant reduction in donor site morbidity. Together with steadily decreasing complication rates, these options have made microsurgical reconstructions a prime choice in plastic surgery, in contrast to the past, where they were considered the "last line of defense."

Prefabricated galeal flap based on superficial temporal and posterior auricular vessels

Scalp layers are widely used in reconstructive procedures. The authors used prefabricated galeal flaps based on the superficial temporal or postauricular vessels for ear, cheek, mandible, and cranium reconstructions in three cases. In case 1, synchronous beard and ear reconstructions were accomplished by using the temporoparietal and retroauricular flaps. In case 2, a buccomandibular defect was reconstructed by transposing the supra-auricular and retroauricular galea with prefabricated bone and skin. In case 3, an epidural hematoma in the left frontoparietal area was evacuated after a circular craniectomy. The harvested bone was not put back on the defect area but buried between the periosteal and galeal layers because of brain edema. These layers were raised as an osteogaleoperiosteal flap and transposed onto the defect area after 7 weeks. When used with a prefabrication method, scalp layers offer versatile options for repairing composite defects of the head region. A galeal flap based on the posterior auricular vessels is practical and reliable in reconstructive procedures. The authors suggest that this flap is an option in cases in which the temporoparietal fascia artery or the superficial temporal artery is not available. Prefabrication of the harvested cranial bone inside the adjacent tissues offers several advantages in that a viable bone is provided at the end of the procedure, intervention at a distant area is avoided, the graft is placed on osteogenic tissue (periosteum) that is also transposed onto the defect, and sophisticated procedures such as microsurgical techniques are not needed.

The posterior interosseous reverse flap: experience with 113 flaps

The authors have used a posterior interosseous flap for resurfacing in 113 cases of hand injury during the past 13 years. Its main indications were complex hand trauma or burn injuries with large skin loss, either acute or postprimary. Flaps survived completely in 98 patients. Twelve patients had superficial necrosis of the distal part of the flap, which did not require additional surgical procedures. Three flaps were lost and alternative coverage was used. Six patients demonstrated paralysis of the motor branch to the extensor muscles of the wrist or fingers (generally to the extensor carpi ulnaris, the extensor digiti quinti, or the extensor pollicis longus). All recovered completely within 6 months. The donor area was closed directly in 3 to 4-cm-wide flaps, leaving an inconspicuous scar. Larger flaps required skin grafting. Donor site morbidity was minimal. Major anatomic variations precluding the use of the flap were encountered twice in this series.

Maximizing flap survival in a prefabrication model using exogenous and endogenous bFGF: a new approach

Flap prefabrication is dependent on the neovascular response that occurs between the implanted arteriovenous pedicle and the recipient tissue. Augmentation of this neovascular response with angiogenic growth factors would maximize flap survival and minimize the interval between pedicle implantation and flap rotation. Maximizing the biologic activity of endogenous growth factors would likewise positively impact upon flap survival. This study examined the role of basic fibroblast growth factor, a known potent angiogenic growth factor, on flap survival in a rabbit ear prefabrication model. Sucrose octasulfate, a substance that binds basic fibroblast growth factor, stabilizes it, and protects it from degradation, was also studied to determine its impact on flap survival. Flap survival was increased using basic fibroblast growth factor, sucrose octasulfate, and the two substances combined together. The use of substrates designed to maximize the biologic activity of endogenous growth factors, rather than relying on the artificial addition of exogenous growth factors, represents a new approach in the search for methods that will improve flap survival.

Reverse posterior interosseous flap based on an exteriorized pedicle to cover digital skin defects

The posterior interosseous arterial flap is limited by its short vascular pedicle and proximal axis of rotation to the coverage of defects on the dorsal aspect of the hand and the first web space. The authors present the results of three cases in which these limits were surpassed by extending the wrist and exteriorizing the vascular pedicle, thus causing it to bowstring across the angle created by the extended wrist. When flap inset is complete the vascular pedicle is excised under local anaesthesia. This technique is an amalgamation of an island flap and a traditional pedicle flap and, as such, it is a two-stage procedure.

The development of neovascularisation in flap perfabrication with vascular implantation: an experimental study

Femoral arteriovenous pedicles were implanted beneath the abdominal skin in rats (n = 30) to investigate the development of neovascularisation over time. New vessel formation was assessed by micro-angiography and quantified under light microscopy. Flap viability was assessed by dye injection studies at different time intervals. Two weeks after implantation of the vascular pedicles, neovascularisation was confined to the vicinity of the arteriovenous pedicle only and none of the flaps were viable. At 4 and 6 weeks, 4 out of 6 flaps were viable, with new vessel formation being widespread throughout the subcutaneous tissue. All flaps were viable at 8 and 12 weeks. Neovascularisation in the dermis up to the epidermis was observed after 8 weeks. Neovascularisation in the panniculus carnosus showed a steady increase after 6 weeks. There was a decrease in the total number of vessels at 12 weeks compared to 8 weeks but at 12 weeks the diameters of the vessels were considerably larger. Flap survival was best predicted by the amount of neovascularisation in the panniculus carnosus. In this experimental model, it is concluded that prefabricated flaps should be raised at 8 weeks instead of 4 or 6 weeks after the implantation of an arteriovenous pedicle, to reduce the risk of flap failure.

Durability of prefabricated versus normal random flaps against a bacterial challenge

Numerous reports of flap prefabrication have demonstrated good survival. The durability of these flaps compared with that of other flap types or normal tissue, however, remains unknown. The purpose of this study was to determine how prefabricated flaps respond to a bacterial challenge compared with identically sized normal random-pattern flaps. Rat abdominal cutaneous-panniculus carnosus flaps were prefabricated with a standard-sized groin fasciovascular tissue carrier and then inoculated with Staphylococcus aureus. The prefabricated flaps were divided into two groups. Group one (standard prefabricated flap, n = 24) received no growth factor. Group two (n = 24) received an angiogenic growth factor between the carrier and flap tissue. A random-pattern flap served as a nonprefabricated control (n = 12). Grading of the prefabricated flaps with growth factor versus the standard prefabricated flaps versus controls showed dehiscence (41 versus 37 versus 4 percent), ulceration (21 versus 29 versus 18 percent), erythema/cellulitis (40 versus 44 versus 8 percent), and necrosis (9 versus 29 versus 0 percent). The control flaps had significantly less dehiscence, erythema/ cellulitis, and necrosis than the standard prefabricated flaps. Similarly, the prefabricated flaps with angiogenic growth factor had significantly less necrosis than the standard prefabricated flaps.

CONCLUSIONS

(1) prefabricated flaps were demonstrated to be less durable than random-pattern flaps against a bacterial challenge, (2) angiogenic growth factor may help to improve the durability of prefabricated flaps against bacterial infection, and (3) the biologic behavior of prefabricated flaps is not the same as that of normal tissue and deserves further investigation.

Consideration of a thin flap as an entity and clinical applications of the thin anterolateral thigh flap

A defatted (thinned) anterolateral thigh flap was designed to reconstruct skin defects requiring thin flap coverage. We used this flap as a free flap for five cases of skin defects, and the outcomes of the reconstructions were all successful. The vascular pedicle of this flap, the cutaneous perforator of the lateral circumflex femoral artery, is about 8 cm long and 2 mm in diameter, and it is ideal for microvascular anastomosis. Thinning is performed in about 3 to 4 mm of thickness almost uniformly except for the vascular pedicle. It was ascertained as one of the useful donor sites of the free thin flap. The virtue of the thin anterolateral thigh flap is its uniform thinness compared with other thin flaps reported previously--the thin groin flap and the thin rectus abdominis musculocutaneous flap. We considered thin flaps as an entity, and they are classified into three types.

Impact of tissue expansion on flap prefabrication: an experimental study in rabbits

This study was designed to determine whether tissue expansion after vascular pedicle implantation would increase the survival area of prefabricated skin flaps. In 20 New Zealand white rabbits, the vascular pedicle consisting of the central artery and vein of the left ear was implanted into the neck. At the time of pedicle implantation a subcutaneous pocket was created measuring 5 x 14 cm beneath the implantation site. Tissue expanders of three different sizes and volumes were implanted in the rabbits of three treatment groups. No tissue expander was implanted in the animals of the control group. All flaps were transposed after 3 weeks to the contralateral ear, and flap survival was assessed 1 week later. The increased area of the flap survival was statistically significant in all three treatment groups compared to the nonexpanded flaps (P = 0.003, P = 0.004, P < 0.0001, respectively). In addition there was a statistically significant larger area of survival using a 100-cc expander measuring 5 x 14 cm (the same size as the elevated flap) compared to 40-cc (3 x 5 cm) or to 60-cc (4 x 8 cm) expanders (P < 0.001, P = 0.004, respectively). The one-way analysis of variance and the t-test were used to show statistical differences. We conclude that the time necessary for neovascularisation of the skin flap could be used to expand the tissue, not only increasing the amount of available tissue, but also enhancing the vascularity.

Flap prefabrication using the "vascular crane" principle: an experimental study and clinical application

Techniques for tissue transfer have continued to evolve. Free flap prefabrication represents a further progression of well known plastic surgery principles in the arena of tissue transfer. This report presents an experimental study demonstrating that the repeated use of a vascular pedicle to prefabricate flaps in the rabbit is possible. There is a decrease in flap viability with the second transfer. A clinical case using this repeated transfer or "crane" principle is also reported. We conclude that the repeated use of a vascular pedicle to prefabricate multiple flaps is a viable option in selected cases.

The value of the delay phenomenon in flap prefabrication: an experimental study in rabbits

Neovascularisation of thin skin flaps after arteriovenous pedicle implantation (flap prefabrication) and the impact of the delay mechanism on the viability of these flaps were investigated. Twenty-four full thickness skin flaps were raised in twelve New Zealand white rabbits. Delay incisions were made at the lateral borders of the planned flaps at the same time as pedicle implantation, 1 week before pedicle implantation, or 1 week after pedicle implantation and the flaps based on the implanted vessels raised at 2 weeks after implantation. Flap survival assessed at 1 week was found to be improved when flap delay was performed 1 week before or after pedicle implantation. Angiographic studies demonstrated an increased density and linearity of the vascular pattern in these delay group flaps. The combination of the time-tested concept of delaying a flap with the newer technique of flap prefabrication appears to improve flap viability.

Manipulating prefabricated flaps: an experimental study examining flap viability

As flap prefabrication becomes a more commonly used clinical tool, it is necessary to investigate the limitations of this technique. Reconstructive procedures of the face often require "custom fitted" flaps to satisfy esthetic demands. This study examines and compares the safety of manipulating thin prefabricated skin flaps versus established axial pattern skin flaps. Twenty-seven New Zealand white rabbits were used to determine if prefabricated flaps can be folded 180 degrees around the edge of the rabbits' ears. The survival of these folded prefabricated flaps was compared with the survival of axial pattern flaps sutured into an identically recipient site. In addition, flaps prefabricated in the same manner were sutured onto a straight recipient bed to evaluate the viability of the newly vascularized tissue. The folded prefabricated flaps had reduced survival (56%) compared to equivalent folded axial pattern flaps (85%), P < 0.005. The nonmanipulated prefabricated flaps and axial pattern flaps survived completely.