Experimental study on axial pedicled composite flap prefabrication with high density porous polyethylene implants: medporocutaneous flap.

Composite flaps including soft tissues with bone or cartilage are widely used in reconstruction of three-dimensional defects, but have some disadvantages. Flap prefabrication with alloplastic implants is an alternative procedure. Axial pattern vascularised high density porous polyethylene (HDPP) implants are capable of sustaining skin grafts. The purpose of this study was to examine the vascularisation pattern of the skin island in a composite flap prefabrication model prepared with vascularised HDPP implants. Forty male Wistar rats divided into four groups were used. A 9.5 x 6 x 2 mm HDPP block was centered on the dissected saphenous pedicle and anchored under the abdominal skin in the experimental group I (n=10). In experimental group II (n=10) saphenous artery and vein were put between the skin and the implant. Thus, the structures were laid as skin, HDPP block, pedicle in experimental group I and skin, pedicle, HDPP block in experimental group II. HDPP block-implanted and pedicle-implanted only groups served as control groups I and II, respectively. Eight weeks after prefabrication, skin islands 1.5 x 5 cm in size incorporated with implants were elevated based on saphenous vessels in the experimental groups and skin islands only based on the pedicle in control group II. Skin islands of the same dimensions were raised as grafts in control group I. Nylon sheets were put under the flaps and grafts to prevent vascularisation from the recipient bed. Flap viability was assessed by measuring the surface area on the 7th day. Total necrosis developed in composite grafts of control group I. Flap survival was higher in experimental group II and control group II (45% and 46.8%) than in group I (29.28%). Histologic studies demonstrated fibrovascular ingrowth into the HDPP implants, except in control group I, with significant inflammatory response and necrosis. Vascularisation of skin and implants from the pedicle was seen also microangiographically. In conclusion, a composite flap prefabrication model including vascularised HDPP implant, skin and vascular carrier was developed. This new flap was termed a 'medporocutaneous flap'.     

A vascularised periosteal flap: anatomical study.

Twenty-seven anatomical studies were done to elucidate the periosteal blood supply on the lateral surface of the shaft of the tibia. The dissection of a vascularised periosteal flap is described. The applications of this flap are discussed in the light of previous clinical and experimental reports on periosteal flaps and a successful clinical case is detailed. This flap has application for electively treating bony non union. It may also be used as a free flap in an acute trauma situation involving bone loss.     

A new flap model in rats: iliac osteomusculocutaneous flap

Although osteomusculocutaneous flaps are used frequently in clinical practice to repair defects involving soft tissue and bone, there are still many questions that remain to be answered regarding their basic physiology. To accomplish such basic science studies, simple and reliable animal osteomusculocutaneous flap models are needed. The purpose of this study was to describe a new flap model in rats--namely, the iliac osteomusculocutaneous flap. Thirty adult Wistar rats weighing 200 to 250 g were used in this experiment. In 15 rats, the vascular anatomy of the iliolumbar vessels and their relation with adjacent soft tissues and the iliac bone was determined by anatomic dissection. Based on this anatomic study, the iliac osteomusculocutaneous flap model was created in rats. The flap is comprised of a skin island (3 x 3 cm) in the flank region, a 1 x 1-cm segment of iliac bone, and an abdominal wall muscle cuff. In 10 rats, the flap was raised as an island flap based on its vascular pedicle of iliolumbar vessels, and was replaced in situ. In the remaining 5 rats, the flap was transferred to the groin region as a free flap. Direct observation on postoperative day 7 revealed that the skin island of all the flaps was completely viable. Bone scintigraphy performed on postoperative day 3 in free flaps demonstrated radionuclide uptake, indicating viability of the bony segment. The dye injection study revealed ink staining within blood vessels of the bone, confirming its viability. Microangiography of the flap demonstrated vascularity of each component of the flap by the iliolumbar vessels, including a distinct branch to the iliac bone. The authors conclude that the iliac osteomusculocutaneous flap of the rat is a simple and reliable flap model that offers the following advantages: (1) It is a true osteomusculocutaneous flap, (2) it can be used as a free flap without the need for an isogeneic rat, (3) the vascular pedicle is consistent, and (4) it is harvested from a small-animal species.     

Articular cartilage defects in a rabbit model, retention rate of periosteal flap cover

BACKGROUND: A periosteal flap is frequently used in procedures involving repair of articular cartilage defects. Hypertrophy of the repair tissue, probably from a retained periosteum, is a clinical problem but not much is known about this issue. The objective of the present experimental study was to investigate the retention rate of periosteal flaps with respect to various postoperative mobilization regimes and the introduction of bone marrow elements underneath the flap. METHOD: We created a chondral lesion (diameter 4 mm) in both patellas of 18 New Zealand white rabbits. The subchondral bone was left intact in one knee. In the other, the bone plate was perforated, allowing bone marrow elements to enter the defect. All defects were covered with a periosteal flap, sutured and glued to the rim of the cartilage defect. Postoperatively, the rabbits were allocated to one of three groups: A. rehabilitation in cages for 4 days, then killed; B. rehabilitation in cages for 7 days, then free activity on the floor of a 10 m2 room until the end of the second week, then killed; C. rehabilitation in cages for 2 weeks, then killed. RESULTS: 16 of 23 periosteal flaps became detached within 2 weeks (one knee was excluded because of clinical signs of infection), with no difference in the retention rate with respect to mobilization regime or established access to bone marrow elements in the defect. The periosteum still served as a cover of the defect in 10 of 12 knees at day 4. This figure decreased to 7 of 23 knees at day 14. CONCLUSION: Our study is the first to document the retention rate of periosteal flaps in a rabbit model. The low retention rate observed may explain why periosteal hypertrophy is not reported in experimental studies where the periosteal flap is sutured to the cartilage rim.     

New experimental composite flap model in rats: gluteus maximus-tensor fascia lata osteomuscle flap

Experimental animal models need to be developed for studies of composite flaps that have often recently been used for defects of both bone and soft tissues. A consistent anatomy, simple surgical technique, and reliable blood flow are essential for the success of experimental flap studies. Here we propose a gluteus maximus-tensor fascia lata osteomuscle flap in rats as a model of these qualities. Gluteus maximus and tensor fascia lata muscles and the adjacent iliac bone segment were combined as a lateral circumflex femoral artery-based flap. To test the reliability of this composite flap, three types of composite tissues were harvested and replaced: osteomusculocutaneous flap, osteomuscle flap, and osteomuscle composite graft. The osteomusculocutaneous flap was elevated by including a skin island over the gluteal region. The osteomuscle graft was formed by deliberately dividing the vascular pedicle of the osteomuscle flap. Direct observation revealed complete necrosis of the skin islands in all osteomusculocutaneous flaps. Microangiography of the flap demonstrated that both muscles and the attached bone were supplied by the pedicle. Dye studies with nitro blue tetrazolium (NBT) and India ink demonstrated dye uptake in both muscle and bone components in osteomuscle flaps. Histological examinations also demonstrated the viability of both tissues only in the flap group. Bone scintigraphy performed in flaps on postoperative day 7 demonstrated radionuclide uptake, confirming perfusion of the bony segment. The gluteus maximus-tensor fascia lata osteomuscle flap is a reliable and simple model for composite flap studies that offers the following advantages: 1) it is a new composite flap which includes bone, 2) it can be dissected easily with the naked eye, without using the microscope, 3) it has a long pedicle for flap displacement, and 4) it is a small animal model.     

A new flap model in the rat: the pectoral skin flap

The purpose of this study was to describe a new axial-pattern experimental flap model in the rat. Wistar rats weighing 200 to 250 g were used in the experiment. In 15 rats, the superficial anatomy of the ventral thoracic region was studied by anatomic dissection, dye injection, and microangiography, using 5 rats in each group. The anatomic studies revealed that the ventral thoracic skin derives its principal blood supply from the long thoracic artery--a branch of the common thoracic artery. Based on these anatomic studies, the pectoral skin flap model, pedicled on the long thoracic vessels, was created in the rat. The flap is bounded medially by the midsternal line, laterally by the anterior axillary line, and superiorly and inferiorly by transverse lines passing at the level of the suprasternal notch and the xyphoid process respectively. In 5 animals, bilateral flaps (N = 10) were raised and replaced in situ. In 15 animals, oversized flaps were created by extending the flap for both a greater width (N = 10) and length (N = 10). Although all the flaps limited to the cutaneous territory as described were found to survive totally, oversized flaps underwent partial necrosis distally. The authors conclude that the pectoral flap is a simple and reliable skin flap model for future biological and pharmacological study because it is very easy to raise, has a consistent vascular pedicle, and has well-defined borders with consistent landmarks.     

Articular cartilage defects in a rabbit model,retention rate of periosteal flap cover

Background A periosteal flap is frequently used in procedures involving repair of articular cartilage defects. Hypertrophy of the repair tissue, probably from a retained periosteum, is a clinical problem but not much is known about this issue. The objective of the present experimental study was to investigate the retention rate of periosteal flaps with respect to various postoperative mobilization regimes and the introduction of bone marrow elements underneath the flap.

Method We created a chondral lesion (diameter 4 mm) in both patellas of 18 New Zealand white rabbits. The subchondral bone was left intact in one knee. In the other, the bone plate was perforated, allowing bone marrow elements to enter the defect. All defects were covered with a periosteal flap, sutured and glued to the rim of the cartilage defect. Postoperatively, the rabbits were allocated to one of three groups: A. rehabilitation in cages for 4 days, then killed; B. rehabilitation in cages for 7 days, then free activity on the floor of a 10 m2 room until the end of the second week, then killed; C. rehabilitation in cages for 2 weeks, then killed.

Results 16 of 23 periosteal flaps became detached within 2 weeks (one knee was excluded because of clinical signs of infection), with no difference in the retention rate with respect to mobilization regime or established access to bone marrow elements in the defect. The periosteum still served as a cover of the defect in 10 of 12 knees at day 4. This figure decreased to 7 of 23 knees at day 14.

Conclusion Our study is the first to document the retention rate of periosteal flaps in a rabbit model. The low retention rate observed may explain why periosteal hypertrophy is not reported in experimental studies where the periosteal flap is sutured to the cartilage rim.     

A new experimental flap model: free muscle perforator flap

A large number of perforator flap types have been described in experimental and clinical studies. Perforator flaps have been used both as pedicled and free flaps in clinical practice, but only in a pedicled form in animal studies. According to the authors' literature review, a free perforator flap in an animal model has not yet been developed. The purpose of this study was to describe a new free perforator flap model in the rat. A total of 15 Wistar rats weighing 200 to 250 g were used in this experiment. In 5 rats, the vascular anatomy of the popliteal vessels and their relation with adjacent structures were determined by anatomic dissection. In the remaining 10 rats, a posterior thigh perforator-based flap was created based on the distal popliteal vascular pedicle. In 5 rats the flap was transferred to the groin region as a free flap. In the remaining 5 rats the flap was transferred to the groin region, but in this group anastomosis was not performed between the vascular structures of the flap and the recipient femoral vessels. The latter group was designated as the control group. Direct observation and microangiographic techniques were used to assess the viability of the flap. Results showed that the cutaneous islands of all the free flaps survived completely, whereas in the control group all the flaps under-went total necrosis. The authors conclude that the free posterior thigh perforator flap is a reliable and true perforator flap model for future physiologic, biologic, and pharmacologic studies. It offers the following advantages: 1) Arising from the biceps femoris muscle, the musculocutaneous perforator of the flap has a consistent vascular pedicle, 2) it is the first free perforator flap for the rat, 3) it is harvested from a small-animal species, and 4) it can be used without the need for an isogeneic rat.     

Prefabricated osteocutaneous neural island flap model

Neural-based flaps are an interesting clinical choice particularly in difficult cases that may not be reconstructed with known techniques. Their popularity is gradually increasing because these flaps offer the advantage of preservation of major extremity arteries and avoidance of microsurgical techniques. Our aim was to explore the feasibility of prefabrication of an osteocutaneous neural island flap model in this study. A peripheral nerve of the rat was implanted into the subcutaneous tissue of a skin flap that was connected to a segment of bone by a soft-tissue bridge, to prefabricate an osteocutaneous flap that was supplied only by the intrinsic vasculature of that nerve after a preliminary delay period. At the end of this study, based on direct observation, microangiographic findings, and additionally, a detailed histologic analysis consisting of both qualitative and quantitative assessments, we have proved that it was possible to prefabricate an osteocutaneous composite flap based on the vascularity of a peripheral nerve after a 2-step delay period. We believe that the clinical application of this new flap will gradually develop based on further experimental studies.     

Bone flap prefabrication: an experimental study in rabbits

The usual method to prefabricate a bone flap is to harvest a nonvascularized bone graft and to implant the artery and vein bundle between segments of bone graft. The basic problem of this method is sacrificing an artery for prefabrication. Another method for creating flap donor sites without using an artery is venous flap prefabrication. There are a few articles describing bone flap prefabrication, and these include implantation of both artery and vein as a vascular bundle. Also, there is no experimental study in the literature using a vein or an arterialized vein pedicle for bone flap prefabrication. As an experimental model for bone flap prefabrication, the rabbit ear vascular model was chosen. For the experiments 3 groups were formed. Each group contained 5 rabbits. In the first experimental group a vein was implanted between the halves of bone graft. In the second experimental group an arterialized vein was implanted between the halves of bone graft. To compare the viability of the bone graft of the 2 prefabrication groups, a bone graft was implanted into the subcutaneous pocket of the posterior auricular area in the third group. The authors examined 5 rabbits in each group by microangiography at the end of 6 weeks except for group 3. On microangiographic analysis, groups 1 and 2 showed patency of the vascular pedicle. There was no difference between these 2 groups from the point of view of vascular patency and bone appearance. Bone scintigraphy was performed for 5 rabbits in each group. On bone scintigraphic scans, the bone component of the flaps was visualized in groups 1 and 2, but not in group 3. A quantitative analysis of images was performed by drawing symmetric spherical regions of interest (ROIs) over both the implanted area and cranial bone. The uptake ratios were computed by dividing the mean counts in the implanted ROI by mean counts in the cranial bone ROI. The mean value was 0.86 +/- 0.02 in group 1 and 0.86 +/- 0.04 in group 2. A statistically significant uptake difference was not seen between venous and arterialized venous groups (P < 0.01). Histologic examination was performed all rabbits in each group, and demonstrated that the bony component was viable, showing osteocytes containing lacunae, osteoblasts along bony trabeculae, and vascular channels in groups 1 and 2. In group 3, the bony architecture of the graft was still apparent, but all bone within it was dead. There were no significant microangiographic, histologic, and scintigraphic differences between the 2 experimental methods.     

A new flap prefabrication model: prefabricated neural-island flap

The purpose of this study was to explore the feasibility of a new flap prefabrication method. A peripheral nerve was implanted into the subcutaneous tissue to prefabricate a skin flap that was supplied solely by the intrinsic vasculature of that nerve after a preliminary delay period. The study was composed of 2 parts. In the first part, anatomic dissections were performed to discover the anatomy and the potential nerve to be used as a pedicle for prefabrication of a skin flap. At the end of these dissections, we decided to use the sciatic nerve as the vascular source and the lumbar region skin for prefabrication of the flap. In the second part, 2 groups were formed. In the first group (prefabricated neural island flap group) after dissection of the nerve, it was transected from its distal part, rotated to the dorsum of the rat, and implanted into the subcutaneous tissue of the skin flap prepared in this area. The delay procedure was completed in 2 periods and at the end of the second delay period, the neural island flap was harvested solely based on the nerve itself. In the second group, the same procedures were repeated with the exception that the sciatic nerve supplying the island flap was ligated and transected just after the second delay period, and the skin flap was replaced in situ as a graft. The mean survival of the skin flaps in the prefabricated neural island flap group was 93.9% ± 4.40%, whereas the survival in the graft group was 0.9% ± 1.44% on postoperative day 7. The microangiographic and the histologic findings were in accordance with direct observation. In this study, we have experimentally demonstrated that, a skin flap that is supplied solely by the intrinsic vasculature of a nerve can be prefabricated after the implantation of that nerve into the subcutaneous tissue of that flap after a preliminary delay period. We termed this "Prefabricated Neural-Island Flap." We believe that the clinical application of this new flap will gradually develop on the basis of further experimental studies.     

血管内皮祖细胞和血管内皮生长因子促进预构皮瓣血管新生作用的比较

目的 比较血管内皮祖细胞(endothelial progenitor cells,EPCs)与血管内皮生长因子(vascular endothelial growth factor,VEGF)在促进预构皮瓣血管新生作用上的差异,探讨EPCs移植提高预构皮瓣存活面积的可行性.方法 分离雄性Wistar大鼠(45只)一侧股血管柬,转位植入腹部皮下,建立预构皮瓣实验模型.将体外诱导分化的EPCs(组Ⅰ,n=15)和VEGF(组Ⅱ,n=15)分别注射于皮瓣局部,对照组仅注射PBS溶液(组Ⅲ,n=15).4周后形成以植入血管为蒂的岛状皮瓣,原位缝合;术后7 d对皮瓣存活率、血管密度计数进行检测.结果 组Ⅰ、组Ⅱ、组Ⅲ的皮瓣存活率分别为(87.26±10.13)%、(66.13±9.9)%、(55.59±13.06)%,组Ⅰ分别与组Ⅱ和组Ⅲ比较,差异均有统计学意义(P<0.001);微血管密度分别为:(38.67±9.52)个/mm~2、(25.83±6.33)个/mm~2、(26.5±5.61)个/mm~2(P<0.05).结论 EPCs促进预构皮瓣血管新生的作用优于VEGF,局部应用骨髓来源的EPCs可以有效地提高预构皮瓣存活面积.     

Fat tissue as a new vascular carrier for prefabrication in reconstructive surgery: experimental study in rats

Several vascular carriers for different tissues were used for the purpose of fat tissue prefabrication. However, the inguinal fat pad in rats can be elevated with a vascular pedicle and considered as a vascular carrier. To the best of our knowledge, the fat tissue in rats as a vascular carrier has not been reported in any experimental studies to date. In our study, we aimed to describe a new prefabrication model in rats in which skin prefabrication was accomplished using the inguinal fat pad as a vascular carrier. Inguinal fat pads in rats were elevated over a superficial epigastric vessel pedicle in the pilot study. The contralateral inguinal fat pads were prepared as grafts. After 1 week, we compared the histopathological findings of the inguinal fat pad flaps and grafts and determined that the inguinal fat pad can be safely elevated over the vascular pedicle. In the experimental group, bilateral vascularised inguinal fat pads were transferred to the lower abdomen for skin prefabrication. After 3 weeks, bilateral fat-skin composite flaps including prefabricated lower abdomen skin were elevated over the vascular pedicles. One side was used as a composite flap while pedicle of the other side was transected at its origin at the femoral vessels to create the composite graft. Composite flap and graft were inserted at their original positions. One week later, the composite flaps were stained with India ink, perfused by fluorescein, and filled with contrast material for microangiographic study. In the histological examination, fat and skin tissues of the composite flaps were viable while those of the composite grafts were necrotic. Based on these findings, we can conclude that the fat tissue as a vascular carrier can be successfully used for tissue prefabrication in plastic surgery.     

Gene therapy with adenovirus-mediated VEGF enhances skin flap prefabrication

We investigated the feasibility in rats of enhancing skin-flap prefabrication with subdermal injections of adenovirus-encoding vascular endothelial growth factor (Ad-VEGF). The left saphenous vascular pedicle was used as a source for vascular induction. A peninsular abdominal flap (8 x 8 cm) was elevated as distally based, keeping the epigastric vessels intact on both sides. After the vascular pedicle was tacked underneath the abdominal flap, 34 rats were randomly divided into three groups according to treatment protocol. The implantation site around the pedicle was injected with Ad-VEGF in group I (n = 10), with adenovirus-encoding green fluorescent protein (Ad-GFP) in control group I (n = 14), and with saline in control group II (n = 10). All injections were given subdermally at four points around the implanted vessel by an individual blinded to the treatment protocol. The peninsular flap was sutured in its place, and 4 weeks later, an abdominal island flap based solely on the implanted vessels was elevated. The prefabricated island flap was sutured back, and flap viability was evaluated on day 7. Skin specimens were stained with hematoxylin and eosin for histological evaluation. In two rats from each group, microangiography was performed to visualize the vascularity of the prefabricated flaps. There was a significant increase in survival of prefabricated flaps in the Ad-VEGF group compared to the control groups: Ad-VEGF, 88.9 +/- 6.1% vs. Ad-GFP, 65.6 +/- 9.4% (P < 0.05) and saline, 56.0 +/- 3.4% (P < 0.05). Sections from four prefabricated flaps treated with Ad-GFP revealed multiple sites of shiny deposits of green fluorescent protein around the area of local administration 1 day and 3 weeks after gene therapy. Histological examination done under high-power magnification (x400) with a light microscope revealed increased vascularity and mild inflammation surrounding the implanted vessel in all groups. However, we were unable to demonstrate any significant quantitative difference with respect to vascularity and inflammatory infiltrates in prefabricated flaps treated with Ad-VEGF compared with controls. Microangiographic studies showed increased vascularity around the implanted pedicle, which was similar in all groups. However, vascularization was distributed in a larger area in the prefabricated flaps treated with Ad-VEGF. In this study, the authors demonstrated that adenovirus-mediated VEGF gene therapy increased the survival of prefabricated flaps, suggesting that it may allow prefabrication of larger flaps and have the potential to reduce the time required for flap maturation.     

A reverse-flow composite flap in the rat.

Reverse-flow flaps are currently particularly used for the reconstruction of defects of the distal part of the extremities. Despite their common usage there have been many reports of postoperative complications, especially resulting in partial or total flap necrosis. There is insufficient knowledge of flap haemodynamics, physiology and wound healing properties in reverse-flow flaps. Development of the proper experimental models is needed to investigate these issues. The purpose of this study was to describe a new reverse-flow flap model in the rat. A total of 20 adult Wistar rats weighing 200-250 g were used in this experiment. In five rats, the vascular anatomy of the auricle of the rat was determined by anatomic dissection and microangiography. In the experimental group (N=5), 1x1 cm reverse-flow composite flaps were harvested as a semi-island shape, based on the distal course of the medial branch of the anterior auricular artery. In the control group, consisting of five rats, the flap was designed and raised based on the proximal course of the medial auricular artery, again in a semi-island shape. In the remaining five animals, a square-shaped composite tissue of the whole layer of the auricle, 1x1 cm in size, was harvested dividing all the bases circumferentially. The composite tissue was replaced in situ. While the former was considered a conventional antegrade-flow flap subgroup, the latter was designated as a graft subgroup. All flaps were replaced in situ. The survival of the flap was evaluated on postoperative day 7 by direct observation and microangiography. The skin island of all the reverse-flow flaps and conventional antegrade-flow flaps survived completely giving a success rate of 100%, whereas all grafts in the control group underwent complete necrosis. Microangiographic studies revealed the vascularity of the reverse-flow and antegrade-flow flaps, identifying the course of the auricular arteries. In conclusion, with its evident advantages of easy to design and harvesting, reliable survival pattern and consistent vascular structure, our new flap model will provide a means for future studies on flap haemodynamics, physiology in reverse-flow flaps.     

The superficial inferior epigastric artery fascia flap in the rabbit

In reconstructive surgery, fascial flaps provide thin, pliable tissue for mucosal closure or serve as a highly vascularized support for skin grafts. Their angiogenic potential is used for experimental neovascularization of avascular tissue grafts. However, most fascial flaps in animal surgery have random pattern design with short reach. As a pilot study for a femur revascularization project in rabbits, a new axial fascial flap is described based on the superficial inferior epigastric (SIE) vessels. They were used in this species previously only as ligated bundles or in fasciocutaneous flaps. The topographical anatomy of the SIE-vessels, lower abdominal fascia, and panniculus carnosus are outlined. The angiogenic capabilities are demonstrated microangiographically by abundant vessel formation in a femur allograft. Used in a pedicled fashion, this flap is an alternative to femoral and saphenous vessels for prefabrication or revascularization procedures in the lower abdomen, genital area, and thigh. Distant recipient sites seem possible with microsurgical transfer.     

Fat prefabrication using a fascial flap in the rat model.

Prefabrication of fat tissue using a fascial flap based on the superficial inferior epigastric artery was studied in rats. First, the superficial inferior epigastric fascia was transposed over the inguinal fat pad. Two weeks later fascia and fat were elevated together as a prefabricated composite flap. At this stage, a pilot study was done in ten rats and perfusion of the flaps was tested with fluorescein. After confirming fluorescein staining of the prefabricated flaps, the study continued with experimental and control groups of rats. In the experimental group, prefabricated flaps were transposed to the subcostal area. In the control group, the pedicles of the flaps were severed, creating composite grafts. These grafts were transferred to the subcostal area in the same manner as in the experimental group. One week later the flaps were re-elevated and grafts were exposed. Fluorescein tests and Indian ink microangiography were carried out. In the experimental group, the flaps were stained, while grafts in the control group were not stained. Fat and fascia were found to be viable in the experimental group, while they were necrotic in the control group on histopathological examination. Based on these findings, we can conclude that the prefabrication of fat by vascular fascia is successful and may have application in plastic surgery.     

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.     

A rat musculocutaneous flap model: the biceps femoris musculocutaneous flap

The purpose of this study was to describe a new musculocutaneous flap model in the rat. A total of 25 Wistar rats weighing 200 to 280 g were used in this experiment. In 15 rats, the vascular anatomy of the biceps femoris muscle and the cutaneous blood supply of its overlying posterior thigh skin were studied by anatomic dissection, dye injection, and microangiography using 5 rats in each group. The anatomic studies revealed that the main axial vessel supplying the biceps femoris muscle was the caudal femoral branch of the popliteal vessels. The posterior thigh skin overlying the biceps femoris muscle received a consistent musculocutaneous perforator at the center of the mid-posterior line of the posterior thigh. Based on the caudal femoral-popliteal vascular pedicle, the biceps femoris musculocutaneous flap was created in the rat, comprised of the whole muscle and its overlying posterior thigh skin. The skin paddle was designed as an ellipse with its longitudinal axis paralleling that of the extremity, generally measuring 4 x 2 cm. Island flaps were raised as described and replaced either in situ (N = 5) or transposed to a sacral defect (N = 5). Results showed that the cutaneous islands of all the flaps survived completely. Tetrazolium blue stain used to indicate muscle survival revealed that the average muscle viability was 86.7+/-3.4%. The authors conclude that the biceps femoris musculocutaneous flap is a reliable and true musculocutaneous flap model for future biological and pharmacological studies. It offers the following advantages: It has a consistent vascular pedicle and a musculocutaneous perforator, it supports a relatively large skin island, and there is no risk of autocannibalization of the flap because the flap is located dorsally.     

Free calvarial periosteum graft vascularized by an omental flap in a rat model

Because omental flaps are useful for flap prefabrication and the cambium layer of the periosteum can be osteogenic, we examined whether calvarial periosteum grafted onto greater omentum of rats was osteogenic and suitable for a flap. Distal omentum was wrapped with calvarial periosteum and so the cambium faced the omentum. Grafted omentum was harvested at 1 to 9 days. In other rats, grafted omentum was elevated as a pedicled flap and moved to the abdominal subcutis, to be harvested later at 1 to 5 months after the initial surgery. Bone formation was evaluated histologically, histochemically, and radiographically. On day 3, osteoid had formed. From day 4, calvarial periosteum was revascularized by omentum and bone was forming. New bone was maintained after grafting to subcutis for 5 months. Thus, bone formed by periosteum on the omentum could be used to reconstruct defects of the bone.