Flap Prefabrication Research Articles

Porcine small intestinal submucosa as a carrier for skin flap prefabrication.

The feasibility of porcine small intestinal submucosa (SIS) as a carrier in skin flap prefabrication was examined in this study. Thirty-eight rats were randomly divided into five groups. The saphenous vascular bundle was used as the vascular carrier. In group 1 (n = 8), an arteriovenous fistula was made by anastomosis of distal saphenous artery and vein. A SIS patch (1.5 x 2 cm2) was placed underneath the vascular bundle. In group 2 (n = 8), the vascular bundle was isolated and laid over the SIS patch. The distal saphenous vessels were ligated when the flap was raised. In group 3 (n = 8), an arteriovenous fistula was made without SIS implant. In group 4 (n = 8), the flap was raised with only the vascular bundle with the distal end ligated. After 2 weeks of maturation, the flap was raised with only the vascular bundle. In group 5 (n = 6), SIS was implanted and the flap including the SIS patch was raised and replaced without the vascular pedicles. The survival of the flaps and histology were evaluated at 5 days after flap replacement. The results showed that the average survival area in group 1 was 99% +/- 3% and the survival area in group 2 was 86% +/- 16%. The mean survival areas in group 3 and 4 were 60% +/- 9% and 25% +/- 10%, respectively. No flap survival was observed in the group 5. These were significantly lower than in groups 1 and 2 (p < 0.05, p < 0.01). Histology showed that SIS patch was incorporated into the adjacent connective tissue and increased amounts of neovascularization were seen between the collagenous sheets and dermis. In conclusion, this study demonstrated that porcine SIS can incorporate into the adjacent tissue and induce angiogenesis in flap prefabrication. This biomaterial can provide a scaffold for supporting and enhancing the survival of vascular prefabricated skin flap.

Prefabricated skin flaps in a rat model based on a dermal replacement matrix Permacol™

The reconstruction of three-dimensional structures is one of the most challenging problems in plastic surgery. While shaped frameworks incorporated within soft tissue envelopes often lose their fine detail, the integration of a blood supply to a stable biomaterial scaffold allows skin graft cover and emphasis of fine detail. The aim of this study was to evaluate whether a porcine derived isocyanate crosslinked collagen tissue matrix (Permacol™) could be vascularised from an isolated vascular pedicle and subsequently sustain an overlying skin graft as a pedicled prefabricated flap. A vascular induction technique was employed using the epigastric pedicles in Sprague-Dawley rats to vascularise 2×2 cm 2 pieces of Permacol™ of standard 0.75 and 1.5 mm thickness Permacol™ and laser treated Permacol™ of 0.4 and 0.75 mm thickness. Flaps were able to support overlying skin grafts as early as 2 weeks following vessel implantation and laser treated Permacol™ had an increased vascularity compared to standard Permacol™ with no evidence of degradation. The study showed that Permacol™ could be a useful matrix for use in tissue engineered flaps.

Flap Prefabrication and Prelamination in Head and Neck Reconstruction

Flap prefabrication and prelamination are relatively new concepts in reconstructive surgery. Although closely related, they are two uniquely different techniques. They are primarily employed in reconstructing complex defects that cannot be repaired with simpler and more conventional techniques. For the head and neck, where defects are often complex, donor options few, and aesthetic demands high, the role of prefabricated and prelaminated flaps is becoming increasingly important. Flap prefabrication starts with transposition of a vascular pedicle into a body of donor tissue that otherwise does not possess an axial blood supply. Flap prelamination, on the other hand, starts with addition of tissue layers into an established vascular bed. Both procedures then require a second stage in which a prefabricated or prelaminated flap is transferred to its final location. This article describes our experience with flap prefabrication and prelamination in the head and neck, reviews the literature, and speculates on the future potential of these reconstructive techniques, especially with evolving tissue engineering and embryonic stem cell technologies.

Preserving osseous viability in osteocutaneous flap prefabrication: experimental study in rabbits.

This study presents a technique that preserves osseous viability in prefabricated osteocutaneous flaps with a soft-tissue vascular carrier, with a pedicled skin flap acting as the vascular carrier to neovascularize a partially devascularized bone segment before its transfer. Using a total of 50 New Zealand White rabbits, two groups were randomized as experimental and control animals. In the experimental group (n = 30), a bipedicled dorsal scapular skin flap was anchored with sutures to the scapular bone, by bringing it into contact with the exposed dorsal surface of the bone after stripping the dorsal muscular attachments. Following 4 weeks of neovascularization, the prefabricated composite flaps were harvested, based on the caudally-based dorsal skin flap, after stripping the ventral muscular attachments of the bone. In the control group (n = 20), non-vascularized scapular bone grafts were implanted under bipedicled dorsal scapular skin flaps with sutures. After 4 weeks, prefabricated composite flaps were harvested, based on the caudally-based dorsal skin flap. In both groups, on day 7 after the second stage, the viability of the bony component of the flaps was evaluated by direct observation, scintigraphy, measurement of bone metabolic activity, microangiography, dye injection study, and histology. Results indicated that the bone segments in the experimental group demonstrated a greater survival than in the control group. The authors conclude that this technique of osteocutaneous flap prefabrication preserves the viability of the bony component with a soft-tissue vascular carrier, in contrast to the conventional method of pre-transfer grafting. The technique may be useful clinically in selected cases.

Pre-fabricated lined axial flaps for reconstruction of extensive post-burn facial and forehead full-thickness composite defects

From January 1996 to February 1998, three patients who suffered extensive post-burn facial and forehead composite defects were treated successfully in our Burn Unit. The delto-pectoral flap and reverse radial forearm flap were pre-fabricated with lining of free split skin grafted onto the underside of the flap. The pre-fabricated flaps were sutured in situ for 2 ∼ 3 weeks. The pre-fabricated lined axial flaps were then transferred for the reconstruction of facial and forehead composite defects. The flap had good blood supply and the wounds healed by first intention. The three cases presented all achieved satisfactory functional and aesthetic results. The results show that pre-fabricated lined axial flaps for the reconstruction of extensive facial and forehead composite defects are safe, effective and relatively easy for clinical application.

Endoscopic access to the extremities: the principle of fascial clefts.

Technology for endoscopic surgery has developed rapidly during the last decade. Applications of endoscopic techniques to orthopaedic surgery have been made possible by the use of balloon dissectors. Balloon dissectors create an optical cavity by separating fascial layers of a constant anatomic plane called the fascial cleft. The optical cavity can be maintained with either carbon dioxide (CO2) insufflation or manual retractors. The authors of the present study have developed a safe, reliable technique using a balloon dissector to create such optical cavities in the extremities, pelvis, and acetabulum to facilitate minimally invasive surgery in these areas. The authors' clinical work and fresh cadaver dissection confirms that the fascial cleft is a universal anatomic constant. It can be accessed quickly to facilitate endoscopic procedures, such as bone grafting for delayed unions, tissue expansion for reconstructive surgery, sural nerve harvesting for nerve cable grafting, and microvascular tissue transfer harvesting and flap prefabrication for extremity reconstruction. Twenty-five cases, each with an average follow-up of 34 months, are presented. Indications, results, and complications of balloon-assisted endoscopic surgery are described.

Impact of innervation and exercise on muscle regeneration in neovascularized muscle grafts in rats

The direction of known staged process of regeneration of free muscle grafts was inverted in our experimental rat model from a centripetal to a centrifugal by central implantation of blood vessels into isolated free muscle grafts. The effects of innervation, reinnervation and exercise on muscle fiber regeneration were analyzed at various intervals from 4 to 90 days by morphological and morphometric methods. Reinnervation occurred as well in grafts with the motor nerve left intact as it did in grafts with a severed and reimplanted nerve. Reinnervation proved to be prerequisite for a lasting muscle regeneration. Denervated muscle grafts even after neovascularization underwent irreversible fibrosis. A positive effect of exercise on the early states (30 days) of muscle regeneration was revealed by morphometrical analysis. In the long term (90 days) fiber diameter assimilated in all groups. The animal model mimics a clinical situation of flap prefabrication demonstrating the relationship of functional tissue regeneration and neovascularization. It can be transferred into the acute clinical situation as well as in tissue engineering.

Prefabricated and Prelaminated Flaps for Head and Neck Reconstruction

Flap prefabrication and prelamination are evolving, new techniques that are useful in reconstructing complex defects of the head and neck. Flap prefabrication involves the introduction of a new blood supply by means of a vascular pedicle transfer into a volume of tissue. After a period of neovascularization, this volume of tissue may be transferred, based only on its implanted vascular pedicle. The transfer may be local transposition or by microsurgical transfer. Flap prelamination refers to a technique in which additional tissue is added to an existing flap (without manipulation of its axial blood supply) to make a multilayered flap that may be used for complex, three-dimensional multilayered reconstructions. This technique may be used locally or at a distance, requiring microvascular transfer. Examples of each are described in this article.

BLADDER RECONSTRUCTION USING A PREVASCULARIZED CAPSULAR TISSUE SEEDED WITH UROTHELIAL CELLS

Recent advances in cell biology and tissue engineering have involved various avascular or acellular scaffolds with or without seeded cells. These techniques are frequently complicated by tissue necrosis, contracture and resorption. We used a vascularized matrix prelaminated with autologous cultured urothelial cells to reconstruct bladder wall defects. A silicone block inserted into the right groin of 50 male Wistar rats directly superficial to the inferior epigastric vessels was used to induce capsule pouch formation. Urothelial cells harvested simultaneously and cultured were then suspended in fibrin glue and seeded into the newly formed capsule after removing the silicone block. After 1 week the prelaminated flap was transposed into a surgically created bladder wall defect. Experimental groups included rats with a urothelial cell seeded capsule pouch sacrificed at 1 and 4 weeks, respectively, after bladder reconstruction. In control rats scaffolds were treated only with fibrin glue or saline before transposition. Hematoxylin and eosin and immunohistochemical staining showed a continuous multilayered urothelial lining along the transposed prelaminated capsule flap in the experimental groups with better survival compared to controls treated only with fibrin glue (80% mortality) or saline (100% mortality). The surviving 3 control animals did not have a urothelial lining. Vascularized prefabricated flaps lined with culture derived urothelial cells were successfully used for bladder reconstruction in a rat model. The technique of prefabricating a vascularized scaffold lined with autologous urothelial cells may provide a method for future reconstruction of the genitourinary systems.

Basic Fibroblast Growth Factor Induced Angiogenesis and Prefabricated Flap Survival

Prefabrication of a latissimus dorsi myocutaneous flap was performed in adult male Landrace pigs. Gelfoam sponges were used as a delivery system for basic fibroblast growth factor (bFGF) at the muscle-subcutaneous tissue interface. Skin survival and angiogenesis were augmented in the growth-factor-treated animals. These data support the use of basic fibroblast growth factor to enhance flap prefabrication.

Prefabrication of Combined Composite (Chimeric) Flaps in Rats

The purpose of this study was to prefabricate a new combined composite (chimeric) flap that consists of four different tissues. The tissues were prefabricated around two independent pedicles that ultimately join as a single main pedicle. In the inguinal area of 36 rats, the saphenous and the superficial inferior epigastric (SIE) pedicles were dissected and prepared as vascular carriers. A fascial graft and a local muscle flap were wrapped around the saphenous pedicle. The SIE pedicle was then implanted under the abdominal skin to supply a future skin flap. An ear cartilage graft was also inserted under the abdominal skin and adjacent to the implanted SIE pedicle. After allowing 2-, 4-, 6-, and 12-week prefabrication periods in different groups of nine animals, the prefabricated tissues were raised around two pedicles nourished by the femoral pedicle and then transferred. Flap survival was assessed by observation, microangiography and histology. The skin flaps showed survival rates of 52 +/- 17% (mean +/- standard error of the mean), 64 +/- 16%, 86 +/- 11%, and 100 +/- 0% of the total areas in the 2-, 4-, 6-, and 12-week prefabricated flaps respectively. None of the control grafts that were prepared on the contralateral side survived totally. A significant difference was found between the 12- and 2-week (p < 0.008), 12- and 4-week (p < 0.02), and 6- and 2-week (p < 0.05) prefabrication groups. Histologically, fascial and cartilage grafts, and portions of muscle were viable in the 2- and 4-week groups. Also, noticeable necrosis was found in the skin flaps in these groups. The muscle showed mild (at 2, 4, and 6 weeks) and moderate (at 12 weeks) atrophy. After prefabrication for 6 weeks, all tissues demonstrated good survival. This study shows that a combined composite flap can be prefabricated successfully in rats after a 6-week period of prefabrication.

Prefabricated vascularised supraclavicular flaps for face resurfacing after postburns scarring

We have designed a technique for prefabrication of large flaps to cover the whole face reconstruction for cervicocephalic postburns scarring. Aesthetic improvement and a better quality of life was achieved in all seven patients.

Lateral arm fascial flap: microarterial anatomy and potential clinical applications.

Previously, muscle flaps and the omentum have been used to indirectly vascularize tissues. Induction of synangiogenesis, or indirect vascularization through the formation of collateral vessels, occurs through the development of vascular connections at the interface between the donor and recipient tissues. Unfortunately, muscle and omental flaps are bulky and, when used to salvage ischemic hands and digits, may limit digital range of motion. Additionally, disadvantages to using omentum include a requirement for an intraabdominal procedure and a lack of subsequent donor tissue if the contralateral limb becomes involved at a later time. The purpose of this anatomic study was to develop a customized lateral arm fascial flap (LAFF) which may be used for flap prefabrication or synangiogenesis of non-bypassable ischemia. Detailed anatomic dissections were performed to more thoroughly define the microvascular anatomy of the LAFF. Computer analysis of the data was performed to demonstrate the potential clinical application of using the LAFF. Dissections revealed a consistent pattern of vessels branching within the lateral arm fascia and to the neighboring musculature. In order to optimize the surgical use of available tissue, computer-aided design techniques were used to model a reliable fascial free flap for inducing synangiogenesis while imparting minimal donor-site morbidity. Anatomic studies of the LAFF revealed pitfalls in flap dissection, while computer-generated models illustrated the detailed microarterial anatomy of the LAFF and potential limitations in flap design. Potential clinical applications for use of this low-profile fasciovascular conduit are noted.

Skin flap prefabrication using acellular dermal matrix and cultured keratinocytes in a porcine model.

In an effort to minimize the amount of autogenous tissue that is sacrificed in using a random skin flap, the authors, in a porcine model, implanted 3.0 x 7.0-cm (median thickness, 1 mm) sheets of commercially available nonmeshed acellular dermal matrix (AlloDerm) subcutaneously. After a vascularization period of 2 weeks, the implants were elevated and used as turnover dermal flaps to cover adjacent 3.0 x 3.0-cm full-thickness skin defects. Sheets of autogenous cultured keratinocytes were used for epithelium. The AlloDerm-cultured keratinocyte complex flaps healed without any complications. Measurements for percent contraction of the wound to determine the suitability of AlloDerm as a dermal flap showed that the wounds had contracted an average of 18 +/- 3.6% at 24 weeks. Histological evaluation revealed multilayered keratinocytes and indurations between the cultured keratinocytes and AlloDerm. Fibroblast infiltration and the presence of luminal spaces surrounded by capillary endothelium characteristic of neovascularization of the matrix were also noted. This preliminary study may form the basis for developing other types of prefabricated flaps using AlloDerm and cultured keratinocytes.

Osteocutaneous Flap Prefabrication Based on the Principle of Vascular Induction: An Experimental and Clinical Study

Osteocutaneous Flap Prefabrication Based on the Principle of Vascular Induction: An Experimental and Clinical Study

Delayed prefabricated arterial composite venous flaps: an experimental study in rabbits.

Prefabrication of composite arteriovenous flaps with implantation of an autologous graft (cartilage) or an alloplastic material (porous polyethylene) was studied in 40 rabbits. Abdominal flaps based on bilateral epigastric pedicles were elevated. An ear cartilage graft or a porous polyethylene implant was inserted under the flap. Two weeks after the operation, 10 flaps with cartilage graft and 10 flaps with porous polyethylene were raised, converted to arteriovenous flaps, and resutured in place in the experimental groups. In the other 20 rabbits of the control groups, the flaps (10 with cartilage graft and 10 with porous polyethylene) were raised and resutured in place as conventional axial flaps. At the end of the second and fourth week postoperatively, samples were obtained from the flap tissues (including a part of the graft or implantation material) and were prepared for histologic examination in all rabbits. The viable areas of all flaps were assessed at the end of fourth week after the second operation. The mean survival rates were 99.4%, 99.7%, 99.5%, and 99.8% in the arteriovenous and control flaps prefabricated with cartilage graft and the arteriovenous and control flaps prefabricated with porous polyethylene respectively. The features of wound healing in the experimental and control groups were similar. The study showed that arteriovenous perfusion can nourish a prefabricated flap containing an implanted material (autologous or alloplastic) and these 2-week delayed composite flaps have a similar survival rate to delayed prefabricated conventional axial flaps.

Retalho ósseo pré-fabricado com osso homógeno: estudo da maturação óssea em um modelo experimental

As opções convencionais de tratamento de perdas ósseas, como enxertos e retalhos não são satisfatórias. Com isso uma nova categoria de retalhos, o retalho pré-fabricado (RPF), passou a ser estudada. Foram retirados 42 ossos metatársicos-I das patas traseiras de 21 ratos Wistar. O grupo I (n=21) foi descalcificado e liofilizado e o grupo II (n=21) foi não descalcificado e congelado a -70°C. Após 3 semanas os ossos foram enxertados em 21 animais sobre os vasos epigástricos inferiores nas regiões inguinal direita e esquerda, individualizados por uma lâmina de silicone. Os grupos I e II foram divididos em três subgrupos cada, de acordo com o tempo de permanência (1, 2 e 4 semanas) após a pré-fabricação do retalho. No estudo histológico macroscópico os grupos apresentaram diferenças em morfologia e consistência: o grupo I mostrou perda da arquitetura óssea e da rigidez e grupo II mantiveram sua forma, rigidez e consistência. Na análise qualitativa alterações foram observadas nos fragmentos do grupo desmineralizado e liofilizado, especialmente no subgrupo de 2 semanas. O grupo II não apresentou alteração no aspecto do tecido ósseo mineralizado entre os diversos subgrupos. É nítida a diferença histológica entre os RPF com osso descalcificado e liofilizado quando comparado ao não descalcificado e congelado. A reabsorção óssea gradual sugere que a rotação do retalho deve ocorrer precocemente. Este estudo demonstra a aplicabilidade do osso homógeno para pré-fabricação de retalhos.

Use of Fascial Grafts as an Interface in Flap Prefabrication

An experimental study was conducted to investigate whether a fascial graft can be used as an interface between a vascular pedicle and target tissue to augment tissue survival in a prefabricated flap. Thirty-six male Sprague-Dawley rats were divided into three experimental groups according to the type of the recipient bed prepared for the vascular implantation. The left saphenous vascular pedicle was used as the vascular source. A 9 x 9-cm inferiorly based peninsular abdominal flap was elevated in each animal. In group I, the pedicle was tacked beneath the abdominal flap, in which the epigastric fascial layer was untouched. In group II, a 3 x 5-cm graft of epigastric fascia was harvested from the abdominal flaps under loupe magnification. The graft was sutured back into its original position after a 180-deg rotation. The vascular pedicle was then implanted just beneath the center of the fascial graft. In group III, the same size of epigastric fascia was removed in the same manner as group II, exposing the subcutaneous layer for pedicle implantation. Four weeks later, abdominal flaps were raised as island flaps connected only to the saphenous pedicle and were sutured in place. Flap viability was assessed visually on day 7. Overall, the ultimate flap survival in group I was the largest, with some necrotic areas at the periphery of the flaps. In group II, flap survival was typically centralized over the fascial graft, and crescent-shaped necrosis was noted superiorly. In group III, an almost linear pattern of survival overlying the vascular pedicle was observed. The mean surviving flap area of group I (12.13 +/- 1.615 cm2) was statistically greater than that of group II (8.83 +/- 0.663 cm2, p < 0.001) and group III (6.3 +/- 0.815 cm2; p < 0.001). There was a statistically significant difference between the mean flap survival in groups II and III (p < 0.001). Vascular arborization was examined by microangiography, and specimens were processed for histological staining. In group II, vascularization was distributed in a larger area along the fascial graft in comparison with limited vascularization around the pedicle in group III. In this study it was revealed that the interposition of a fascial graft as an interface between the vascular source and the target tissue seems to increase the size of the prefabricated flap.

Shilov, B. L., and Milanov, N. O. Prefabrication of free flaps using fascia: First experience. (Russian)

Shilov, B. L., and Milanov, N. O. Prefabrication of free flaps using fascia: First experience. (Russian)

Revascularized composite grafts with inserted implants for reconstructing the maxilla — improved flap design and flap prefabrication

We present a new technique including prefabrication of a revascularized composite scapular flap that will fit a maxillary defect exactly. The method is based on careful preoperative planning using three-dimensional reconstructions of data obtained from computed tomograms and stereolithographic models. A pedicled scapular flap with a split skin graft envelope that has endosteal implants already inserted is prepared and covered by a polytetrafluoroethylene (PTFE, Goretex) membrane. After 3–4 months these prefabricated grafts are harvested, inserted into the maxillary defects, and reanastomosed to the facial vessels. Two to three weeks later, after mucosal healing, a prosthesis can be fitted on the endosteal implants. Histological evaluation of the flap shows vital bone reactions and attachment of the split skin graft.