Use of fascial grafts as an interface in flap prefabrication: an experimental study.

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.     

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.     

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.     

Prefabrication of large fasciocutaneous flaps using an isolated arterialised vein as implanted vascular pedicle.

Flap prefabrication represents a new trend in microsurgical tissue transfer. Based on the concept of neovascularisation, in Chinchilla Bastard rabbits (n=40), an isolated venous pedicle dissected from the femoral and saphena magna vein was arterialised by end-to-end anastomosis to the femoral artery at the inguinal ligament. This arterialised venous loop was implanted beneath a random-pattern vascularised abdominal fasciocutaneous flap as large as 8 x 15 cm(2) to investigate the development of neovascularisation at various evaluating times of 4, 8, 12, 16 and 20 days. To prevent neoangiogenesis from occurring between the underlying vascular bed and abdominal flap, a silicone sheet with the corresponding dimension of 8 cm x 15 cm x 0.25 mm was placed and fixed on the abdominal wall. The flap viability and the neovascularisation process in the prefabricated abdominal skin flaps were evaluated by macroscopic observation, blood analysis, selective microangiography and histology. The experimental results showed that newly formed vessels originating from the implanted isolated venous pedicle were evident on the angiograms 4 days after pedicle implantation. In the 8- and 12-day groups, newly formed vessels became larger and some were connected to the originally available vasculature in the abdominal fasciocutaneous flaps. In the 20-day group, entire flaps were perfused by the blood flow supplied from the newly implanted venous pedicles through newly formed vessels and their vascular connections. This study indicated that large flap prefabrication can be created by implantation of an isolated arterialised venous pedicle into a random-pattern vascularised fasciocutaneous flap. Twenty days appears to be the minimal length of time required after arterialised venous pedicle implantation for the maturation of neovascularisation in the prefabricated flap.     

Neovascularization in prefabricated flaps using a tissue expander and an implanted arteriovenous pedicle

Creating prefabricated flaps using tissue expanders in combination with the implantation of maximal blood flow vascular pedicles into suitable tissue areas represents a new tendency in the reconstruction of large skin defects. In 42 Chinchilla Bastard female rabbits weighing 3,700-4,600 g, skeletonized arteriovenous pedicles with maximal blood flow, dissected from the femoral and saphena magna bundles, were implanted underneath abdominal fasciocutaneous flaps. Oval tissue expanders of 250 ml were placed and fixed on the abdominal wall to expand these prefabricated flaps. The evaluation parameters were macroscopic observation, blood analysis, selective microangiography, histology, and scintigraphy. The study results showed that neovascularization in expanded prefabricated flaps was established from newly formed vessels generated from the implanted pedicles and their vascular connections with the originally available vasculature in the flap. After 20 days of prefabrication, the entirety of the expanded prefabricated flaps was perfused by blood flow supplied from newly implanted arteriovenous pedicles. The study indicated that an expanded prefabricated flap can be successfully created by the simultaneous implantation of a maximal blood flow pedicle in combination with flap expansion.     

VEGF促进预构皮瓣血管新生的实验研究

目的探讨VEGF重组蛋白促进大鼠预构皮瓣血管新生、提高皮瓣存活面积的可行性。方法建立大鼠腹部预构皮瓣模型;30只Wistar大鼠随机分为两组;局部应用VEGF165（组Ⅰ）、PBS（组Ⅱ）;4周后形成以植入血管为蒂的岛状皮瓣,原位缝合;术后7d对皮瓣存活、血管新生情况进行检测。结果组Ⅰ、组Ⅱ的皮瓣存活率分别为66．13％±9．9％,55．59％±13．06％（P〈0．05）;组Ⅰ与组Ⅱ比较,微血管显影血管网更丰富,范围更广,分支更粗,内含墨汁的血管在皮瓣的表皮真皮、皮下层均有分布;微血管计数组Ⅰ、组Ⅱ分别为25．83±6．33条／mm^2,26．5±5．61条／mm^2（p〉0．05）。结论VEGF可以促进预构皮瓣的血管新生,提高存活率。     

腺病毒-VEGF基因重组体促进预构皮瓣成活的实验研究

目的：应用大鼠预构皮瓣模型,探讨基因治疗技术产生的血管内皮生长因子促进预构皮瓣血管新生和皮瓣存活的可能性,为临床上寻找加速预构皮瓣成熟的新方法提供实验依据。方法：20只SD大鼠每只腹部两侧各构建一个预构皮瓣,共构建40个皮瓣,每只大鼠两侧皮瓣按随机原则进行不同的处理,分别归于实验组或对照组,每组各20个皮瓣。于大鼠腹部两侧各标记3cm×2cm矩形预构区,短边平行于腹股沟韧带,自尾侧短边中点向后纵向切开后肢皮肤,剥离出长约2cm的股动静血管束,远端结扎切断。在两侧预构区域的中轴线上,于真皮与肉膜层间各制作一皮下隧道,实验组的隧道壁皮下组织内注射携带有VEGF基因的腺病毒,同法向所有对照组的隧道壁软组织内注射等量生理盐水。将已剥离好的血管束向颅侧翻转置入相应皮下隧道内。所有已植入股血管的预购区域2周后均被制成以植入血管束为蒂的岛状皮瓣,从两组中各取一个皮瓣进行免疫组化染色,观察有无VEGF生成,其余岛状皮瓣均缝回原处。形成岛状皮瓣后第七天观察皮瓣存活及血管新生情况。结果：实验组与对照组的皮瓣平均存活率分别为（90．48±1．89）％、（69．75±2．36）％,其差异有统计学意义（P〈0．01）;血管放射显影图上,实验组植入血管周围见广泛白色显影,尤以血管两端明显,而对照组新生血管显影仅局限于植入血管周围;组织学切片显示实验组植入血管周围新生血管丰富,以毛细血管为主,并见肉芽成份,对照组新生血管相对较少,两组间新生小血管管腔大小则无明显差异;免疫组化检测显示仅实验组皮瓣中有VEGF表达。结论：腺病毒-VEGF基因重组体能通过促进预构皮瓣的血管新生,增加预构皮瓣的存活率。     

大鼠隐血管束全腹壁预制皮瓣模型的实验研究

目的:探讨一种以大鼠隐血管束为预制血管蒂的全腹壁预制皮瓣模型的设计及应用价值。方法:将18只SD大鼠按Ⅰ期手术与Ⅱ期手术之间的间隔时间2、4、6周分为三组。Ⅰ期手术制备大鼠后肢隐血管束预制血管蒂,Ⅱ期手术切开皮瓣四边,形成以预制隐血管束为蒂的岛状皮瓣。Ⅰ期、Ⅱ期术后观察皮瓣血运,记录皮瓣成活面积及成活率。检测Ⅱ期皮瓣血管蒂旁局部组织中血管内皮生长因子(VEGF)含量,取成活皮瓣制作病例切片,HE染色,计算血管密度(血管数/mm2)。运用统计学方法比较各组间差异。结果:Ⅰ期术后各组大鼠腹部皮瓣全部成活;Ⅱ期术后1周,Ⅰ组皮瓣全部坏死,Ⅱ组、Ⅲ组皮瓣平均成活率分别为(14.68±1.02)%,(16.19±1.71)%(P<0.05);Ⅱ期皮瓣局部组织VEGF平均含量:Ⅰ组243.95±4.37,Ⅱ组240.89±3.11,Ⅲ组239.19±2.61(P>0.05);大鼠平均血管密度6周组较4周组略有增多,但差别不大(P>0.05)。结论:大鼠隐血管束全腹壁预制皮瓣模型,可以作为研究提高预制皮瓣成活率的基础,Ⅰ期手术与Ⅱ期手术之间的时间间隔至少需4周。     

Viability and versatility of arterialized venous perfusion flaps and prefabricated flaps: an experimental study in rabbits.

The purpose of this study was to investigate the viability of two types of unconventional flaps: 1) the arterialized venous perfusion (AVP) flap; and 2) the prefabricated flap. Four experimental groups were studied: an AVP flap group with assessment of the viability of single and paired flaps nourished by the same vascular pedicle; a prefabricated flap group with the abdominal flap pedicled on the epigastric artery and vein; a prefabricated flap group in which the flap was supplied by an arterialized vein graft (A-V shunt), and paired flaps of different designs, but based on the same vascular pedicle, were investigated; and a free composite graft group. Survival of the skin flaps exceeded 92 percent in each group, except in the free composite group which showed complete necrosis. Results of the study validated that flap viability was independent of flap size (large or small), type (AVP flap or prefabricated flap), and the number of flaps on each vascular pedicle (single or paired).     

Vascularization of skin following implantation of an arteriovenous pedicle: implications in flap prefabrication.

In a rat model, a skin flap was fabricated by implantation of a distally ligated arteriovenous pedicle. The femoral artery and vein were implanted as a unit beneath the abdominal skin, a portion of which was later raised as an island flap, based on these vessels. Percentage area of survival, tissue blood flow, and pattern of vascularity were compared in two groups of flaps. In group I, the pedicle to be implanted was dissected with a cuff of surrounding muscle still attached; in group II, the pedicle was skeletonized to the level of adventitia. Flap survival in the two groups was similar (73% vs. 77%), as was skin blood flow (5.4 vs. 5.7 ml/100 g/min). Angiography demonstrated two principal patterns of vascularization: connection between donor and recipient vessels (inoculation), and sprouting and arborization of new vessels. Strengths and limitations of this and other models of flap "prefabrication" are discussed.     

血管内皮细胞生长因子和碱性成纤维细胞生长因子加速预构扩张皮瓣成熟的研究

目的　观察以生物蛋白胶局部缓释血管内皮细胞生长因子 (VEGF)和碱性成纤维细胞生长因子(b FGF)应用于兔预构扩张皮瓣对细胞增殖及凋亡、血管化进程 ,以及皮瓣成熟的作用。　方法　将新西兰大耳白兔 5 3只随机分为正常、空白、生物蛋白胶、VEGF直接应用、VEGF胶及 b FGF胶共 6组 ,兔耳中央动静脉束植入预构扩张皮瓣 ,14天后形成 3cm× 5 cm岛状瓣。分别进行皮瓣成活面积、激光多普勒血流量、铅丹灌注、墨汁灌注、PCNA免疫组化和 TUNEL 凋亡检测。　结果　两种生长因子应用组皮瓣成活面积较其它组增加 ,血流灌注量增多 ,新生毛细血管密度加大 ,细胞增殖提高、凋亡减少。　结论　 VEGF和 b FGF均能通过刺激细胞增殖和减少凋亡发生来促进血管新生和预构扩张皮瓣成熟 ,用生物蛋白胶缓释生长因子有独特效果。     

重组腺病毒介导的血管内皮生长因子165基因增强大鼠横形腹直肌肌皮瓣活力的研究

目的探讨重组腺病毒介导的血管内皮生长因子165(adenovirusmediatedvascularendothelialgrowthfactor165,Ad-VEGF165)基因,增强大鼠横形腹直肌肌皮瓣(transverserectusabdominismusculocutaneousflap,TRAM)局部缺血区域活力的基因治疗。方法SD大鼠30只,制备30mm×80mm以下腹部血管作为血管蒂的右侧矩形TRAM皮瓣,随机平均分成5组,分别在大鼠TRAM皮瓣皮下、皮下+腹直肌及腹直肌局部注射Ad-VEGF165(1～3组:治疗组),同时在TRAM皮瓣皮下+腹直肌局部注射重组腺病毒载体介导的绿色荧光蛋白(adenovirusmediatedgreenfluorescentprotein,Ad-GFP,4组:重组腺病毒自身对照组)和DMEM培养液(5组:空白对照组),于注射后第7天手术,术后第7天检测各组大鼠TRAM皮瓣成活面积、CD34微血管密度(microvasculardensity,MVD)、VEGF免疫组织化学染色和原位杂交组织化学(insituhybridizationhistochemistry,ISHH)。结果11～3组TRAM皮瓣成活面积分别为14.19±2.77、15.18±2.18、8.30±1.28cm2,均较4、5组4.12±1.86、3.60±1.95cm2明显增加,且差异有统计学意义(P<0.05);21～3组TRAM皮瓣CD34MVD均高于4、5组,差异有统计学意义(P<0.05);31～3组VEGF免疫组织化学染色和ISHH呈阳性表达。结论重组腺病毒载体介导的VEGF165基因局部注射,能增加大鼠TRAM皮瓣局部缺血区域成活面积。     

Effect of transfection time on the survival of epigastric skin flaps pretreated with adenovirus encoding the VEGF gene

An experimental study was conducted to investigate the effect of time of adenovirus-mediated vascular endothelial growth factor (VEGF) gene therapy on the viability of epigastric skin flaps. Eighty-four male Sprague-Dawley rats were used. Skin flaps measuring 8 x 8 cm were marked on the ventral abdominal wall. The upper border of the flap was 1 cm above the costal margin, and the lower border was at the pubis and the inguinal fold. The lateral borders of the flap corresponded to the location of the distinct conversion of the thin ventral skin to the thick dorsal skin. Seven sites in the predicted area of necrosis on the outlined skin flaps were chosen for subdermal injections. All injections were administered by an individual who was blinded to the different treatment groups. The rats received either saline (control group I, N = 28) or adenovirus encoding green fluorescent protein (Ad-GFP; group II, N = 28) or Ad-VEGF (group III, N = 28). The epigastric island skin flaps based solely on the right inferior epigastric vessels were elevated either on the same day of injection (day 0 = 12 hours after transfection, N = 7) or on day 3 (N = 7), day 7 (N = 7), or day 14 (N = 7) after subdermal gene therapy. Flaps were sutured back to their native configuration. Flap viability was evaluated on day 7 after surgery. Sections of the flaps were examined histologically after undergoing hematoxylin-eosin staining. There was a significant reduction in mean percentage of necrotic flap area by 56%, 67%, 70%, and 54% in flaps transfected with Ad-VEGF, 12 hours, 3 days, 7 days, and 14 days before flap elevation, respectively ( < 0.05). There was no evidence that the mean percentage of skin necrosis in the Ad-GFP group was different than in the control group ( = 0.26). There was evidence of mild inflammation in flaps pretreated with Ad-GFP and Ad-VEGF compared with the control group. The authors demonstrated that adenovirus-mediated gene therapy of the abdominal skin after subdermal injections was technically feasible. This was demonstrated by the visualization of GFP expression in control experiments using a fluorescence microscope. In this study, adenovirus-mediated VEGF gene therapy promoted epigastric flap survival, which was not related to the time of transfection. These findings raise the possibility that pretreatment with VEGF gene therapy using an adenovirus vector may be applicable in patients at risk for plastic surgery.     

Prefabrication of skin flaps using vein grafts: an experimental study in rabbits.

Prefabrication provides a new method for creating donor sites which are not limited by natural vascular territories. There are several methods for prefabrication, and these include implantation of greater omentum, blood vessels or muscle flaps. Based on the concept that an arterio-venous (A-V) shunt results in sufficient neovascularisation to support a free flap, we used a rabbit model to investigate the characteristics of these flaps. Prefabrication of an abdominal wall donor site was performed using the left epigastric vein in 20 male New Zealand white rabbits. An 8 x 10 cm skin flap was elevated 10 days after prefabrication, either as an island or a free flap. Survival of the skin flaps exceeded 93% and was independent of position of the vascular pedicle, direction of blood flow, or nature of the flap (island or free flap). Angiograms showed a very rich neovascularisation within the prefabricated flap.     

Use of free interpositional vein grafts as pedicles for prefabrication of skin flaps

Pedicles created from a long vein graft increase the scope and applications of prefabricated skin flaps. This study reports the survival and pattern of neovascularization of lower abdominal skin flaps in rabbits based on a pedicle formed by interposition of a long vein graft between the divided ipsilateral femoral artery and vein. Flaps were elevated 2–5 weeks after pedicle implantation and the surviving area quantitated and vascular patterns examined 1 week later. Only 8 out of 35 flaps were greater than 50% alive, the most frequent cause of flap failure being pedicle non-patency. If the pedicle remained patent, complete flap survival was possible as early as 2 weeks after implantation. In non-patent pedicles, recanalization or formation of a new vascular network may, given at least 4 weeks, be sufficient to ensure partial flap survival. The findings indicate that implantation of a long, skeletonized vein graft is an unreliable method of prefabrication of abdominal skin flaps in this model. © 1994 Wiley-Liss, Inc.     

The fasciovascular pedicle for revascularization of other tissues.

A fasciovascular pedicle based on the epigastric vessels was developed in a rat model to determine if it could be used as a "universal carrier" to revascularize a new composite flap. The effects of time course, carrier size, and flap ischemia on the revascularization process were studied. A 2.5 x 4-cm or 1 x 4-cm fascial patch pedicled on the vessels was transferred under bipedicled 2.5 x 4-, 6-, or 8-cm abdominal panniculocutaneous flaps. At different time intervals, the flap was raised as an island flap connected only by it vascular bundle and then sutured back in place. The skin perfusion by dermofluorometry and flap survival were both markedly increased on day 5 (p less than 0.001). The wide carrier had a 93% survival area, whereas the narrow carrier had only 71%. The wide carrier induced relatively faster and better revascularization (p less than 0.05). Moderate ischemia promoted revascularization (p less than 0.01). An india ink injection study and histological examination provided visual evidence of revascularization. This fasciovascular pedicle is a promising model for prefabrication of complex new composite flaps and for studying the process of revascularization between the layers. Based on these findings and further investigations, a thin, prefabricated abdominal free flap was successfully transferred for facial resurfacing in humans.     

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.     

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.     

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.