Dorsal Skin Flap Research Articles

In vitro and in vivo investigation of Argiope bruennichi spider silk-based novel biomaterial for medical use.

As a natural and biocompatible material with high strength and flexibility, spider silk is frequently used in biomedical studies. In this study, the availability of Argiope bruennichi spider silk as a surgical suture material was investigated. The effects of spider silk-based and commercial sutures, with and without Aloe vera coating, on wound healing were evaluated by a rat dorsal skin flap model, postoperatively (7th and 14th days). Biochemical, hematological, histological, immunohistochemical, small angle x-ray scattering (SAXS) analyses and mechanical tests were performed. A. bruennichi silk did not show any cytotoxic effect on the L929 cell line according to MTT and LDH assays, in vitro. The silk materials did not cause any allergic reaction, infection, or systemic effect in rats according to hematological and biochemical analyses. A. bruennichi spider silk group showed a similar healing response to commercial sutures. SAXS analysis showed that the 14th-day applications of A. bruennichi spider silk and A. vera coated commercial suture groups have comparable structural results with control group. In conclusion, A. bruennichi spider silk is biocompatible in line with the parameters examined and shows a healing response similar to the commercial sutures commonly used in the skin.

Topical Neuropeptide Y for Ischemic Skin Wounds.

Our objective was to investigate the effects of topically applied neuropeptide Y (NPY) on ischemic wounds. Initially, the animal model for ischemic wound healing was validated using 16 male Sprague Dawley albino rats. In the intervention study, an additional 28 rats were divided into three groups: NPY (0.025%), the positive control insulin-like growth factor-I (IGF-I, 0.0025%), and the hydrogel carrier alone (control). The hydrogel was selected due to its capacity to prolong NPY release (p < 0.001), as demonstrated in a Franz diffusion cell. In the animals, an 8 mm full-thickness wound was made in a pedunculated dorsal ischemic skin flap. Wounds were then treated and assessed for 14 days and collected at the end of the experiment for in situ hybridization analysis (RNAscope®) targeting NPY receptor Y2R and for meticulous histologic examination. Wound healing rates, specifically the percentage changes in wound area, did not show an increase with NPY (p = 0.907), but there was an increase with rhIGF-I (p = 0.039) compared to the control. Y2R mRNA was not detected in the wounds or adjacent skin but was identified in the rat brain (used as a positive control). Light microscopic examination revealed trends of increased angiogenesis and enhanced inflammatory cell infiltration with NPY compared to control. An interesting secondary discovery was the presence of melanophages in the wounds. Our findings suggest the potential of NPY to enhance neovascularization under ischemic wound healing conditions, but further optimization of the carrier and dosage is necessary. The mechanism remains elusive but likely involves NPY receptor subtypes other than Y2R.

Standardized Pre-clinical Surgical Animal Model Protocol to Investigate the Cellular and Molecular Mechanisms of Ischemic Flap Healing

BackgroundSome of the most complex surgical interventions to treat trauma and cancer include the use of locoregional pedicled and free autologous tissue transfer flaps. While the techniques used for these reconstructive surgery procedures have improved over time, flap complications and even failure remain a significant clinical challenge. Animal models are useful in studying the pathophysiology of ischemic flaps, but when repeatability is a primary focus of a study, conventional in-vivo designs, where one randomized subset of animals serves as a treatment group while a second subset serves as a control, are at a disadvantage instigated by greater subject-to-subject variability. Our goal was to provide a step-by-step methodological protocol for creating an alternative standardized, more economical, and transferable pre-clinical animal research model of excisional full-thickness wound healing following a simulated autologous tissue transfer which includes the primary ischemia, reperfusion, and secondary ischemia events with the latter mimicking flap salvage procedure.ResultsUnlike in the most frequently used classical unilateral McFarlane’s caudally based dorsal random pattern skin flap model, in the herein described bilateral epigastric fasciocutaneous advancement flap (BEFAF) model, one flap heals under normal and a contralateral flap—under perturbed conditions or both flaps heal under conditions that vary by one within-subjects factor. We discuss the advantages and limitations of the proposed experimental approach and, as a part of model validation, provide the examples of its use in laboratory rat (Rattus norvegicus) axial pattern flap healing studies. ConclusionsThis technically challenging but feasible reconstructive surgery model eliminates inter-subject variability, while concomitantly minimizing the number of animals needed to achieve adequate statistical power. BEFAFs may be used to investigate the spatiotemporal cellular and molecular responses to complex tissue injury, interventions simulating clinically relevant flap complications (e.g., vascular thrombosis) as well as prophylactic, therapeutic or surgical treatment (e.g., flap delay) strategies in the presence or absence of confounding risk factors (e.g., substance abuse, irradiation, diabetes) or favorable wound-healing promoting activities (e.g., exercise). Detailed visual instructions in BEFAF protocol may serve as an aid for teaching medical or academic researchers basic vascular microsurgery techniques that focus on precision, tremor management and magnification.Graphical

Time-related variations in viability of random pattern skin flaps: An experimental study in rats

ABSTRACT Chronobiological variations are in the fabric of life. The first ideas regarding the possible effects of circadian rhythm on surgical outcomes were published in the early 2000s. Some studies support and oppose this idea. The lack of experimental evidence in a controlled setting has led to this study. This study aimed to explore the chronobiological implications of surgical outcomes. The rats were divided into four groups. A random pattern dorsal skin flaps were elevated in all groups at six h intervals. Flap necrosis rates and melatonin, oxidant, and antioxidant factors were studied. Flap survival was better in the 06:00 h group. The flap necrosis was higher in the 18:00 h group. Some of the biochemical parameters displayed circadian variations. As an independent variable, the time of surgical intervention changed the flap survival rates. It should be noted that the study was held in a nocturnal animal model thus the pattern of flap survival can be in reversed fashion in a clinical scenario. This study is the first experimental evidence for “Chronosurgery” in a controlled setting. Further studies in all aspects of surgical disciplines are required.

Metabolic Effects of Electromagnetiс EHF Radiation and Ozone Therapy in the Engraftment of the Skin Flap

The aim of this study was to evaluate the effect of ROS on the intensity of oxidative and energy metabolism in the blood of rats with an operational model of ischemia of the dorsal skin flap in vivo. Our studies have allowed us to establish that the modeling of an extensive skin defect is accompanied by pronounced shifts in oxidative metabolism in the blood plasma of animals. At the same time, in the absence of pathogenetic treatment, signs of oxidative stress are formed, including the intensification of free radical processes and the inhibition of general antioxidant activity in combination with the accumulation of an increased amount of lipoperoxidation products (in particular, malondialdehyde). Conducting experimental therapy with the introduction of ozone or treatment with electromagnetic radiation of the EHF band allows partially compensating for these metabolic disorders, however, the most optimal option is a combination of these factors within a single scheme. It should be noted that the results obtained are of great applied importance for the creation of innovative technologies for the complex medical rehabilitation of orthopedic-traumatological patients as a tool for influencing reparative processes in the lesion to restore and maintain tissue structures.

Papaverine loaded injectable and thermosensitive hydrogel system for improving survival of rat dorsal skin flaps

Vasospasm during reconstructive microsurgery is a common, uncertain, and devastating phenomena concerning flap survival. Topical vasodilators as antispasmodic agents are widely used to reduce vasospasm and enhance microvascular anastomosis in reconstructive microsurgery. In this study, thermo-responsive hydrogel (CNH) was fabricated by grafting chitosan (CS) and hyaluronic acid (HA) to poly(N-isopropylacrylamide) (PNIPAM). Papaverine, an anti-spasmodic agent, was then loaded to evaluate its effect on rat skin flap survival. Post-operative flap survival area and water content of rat dorsal skin flap were measured at 7 days after intradermal application of control hydrogel (CNHP0.0) and papaverine loaded hydrogel (CNHP0.4). Tissue malondialdehyde (MDA) content and superoxide dismutase (SOD) activity was measured using enzyme linked immunosorbent assay (ELISA) to determine oxidative stress in flaps. Hematoxylin and eosin (H&E) staining and immunohistochemistry (IHC) were performed to evaluate flap angiogenesis and inflammatory markers. Results showed that CNHP0.4 hydrogel could reduce tissue edema (35.63 ± 4.01%), improve flap survival area (76.30 ± 5.39%), increase SOD activity and decrease MDA content. Consequently, it also increased mean vessel density, upregulated expression of CD34 and VEGF, decreased macrophage infiltration, and reduced CD68 and CCR7 expression based on IHC staining. Overall, these results indicate that CNHP0.4 hydrogel can enhance angiogenesis with anti-oxidative and anti-inflammatory effects and promote skin flap survival by preventing vascular spasm.Graphical

Exploiting synergistic effect of CO/NO gases for soft tissue transplantation using a hydrogel patch

Autologous skin flap transplantation is a common method for repairing complex soft tissue defects caused by cancer, trauma, and congenital malformations. Limited blood supply range and post-transplantation ischemia-reperfusion injury can lead to distal necrosis of the flap and long-term functional loss, which severely restricts the decision-making regarding the optimal surgical plan. To address this issue, we develop a hydrogel patch that releases carbon monoxide and nitric oxide gases on demand, to afford a timely blood supply for skin flap transplantation during surgery. Using an ischemia-reperfusion dorsal skin flap model in rats, we show that the hydrogel patch maintains the immediate opening of blood flow channels in transplanted tissue and effective blood perfusion throughout the perioperative period, activating perfusion of the hemodynamic donor site. We demonstrate that the hydrogel patch promotes distal vascularization and long-term functional reconstruction of transplanted tissues by inhibiting inflammatory damage and accelerating blood vessel formation.

PD12-11 URETHRAL COMPLICATIONS AFTER METOIDIOPLASTY WITH URETHRAL RECONSTRUCTION

You have accessJournal of UrologyCME1 Apr 2023PD12-11 URETHRAL COMPLICATIONS AFTER METOIDIOPLASTY WITH URETHRAL RECONSTRUCTION Marta Bizic, Marko Bencic, Borko Stojanovic, and Miroslav Djordjevic Marta BizicMarta Bizic More articles by this author , Marko BencicMarko Bencic More articles by this author , Borko StojanovicBorko Stojanovic More articles by this author , and Miroslav DjordjevicMiroslav Djordjevic More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003259.11AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Metoidioplasty represents a variant of phalloplasty for those transmen who require less invasive and one-stage genital affirmation surgery (GAS), which will provide male appearance of genitals with the ability of stand up voiding. METHODS: From February 2006 until January 2022, 967 transmen underwent metoidioplasty with urethral reconstruction in our institution. Urethroplasty technique depended on patients’ anatomy and availability of hairless genital skin: tubularization urethroplasty (95 cases), onlay flap urethroplasty with dorsal clitoral skin flap (12 cases), onlay flap urethroplasty with labia minora (LM) skin flap (34 cases), buccal mucosa graft (BMG) with clitoral skin flap urethroplasty (83 cases), BMG with LM skin flap (676 cases) and LM skin graft with clitoral skin/LM skin flap urethroplasty (67 cases). RESULTS: Follow-up ranged from 9 to 199 months (mean 102 months). During the follow-up period we monitored urethral complications and divided them into early and late. Early urethral complications occurred within a first month postoperatively in 131 patients (13.50%) and included: UTI (7 cases), spraying (34 cases), dribbling (42 cases) and urethral fistula (82 cases). Late urethral complications were present after first postoperative month in 103 patients (10.65%) and during the follow-up period and required further treatment and included: recurrent UTI (1 case), post void dribbling (10 cases), urethral fistula (87 cases), urethral stricture (17 cases), and inability to empty the bladder completely (2 cases). In our patients’ group between 1.76% and 2.79% had more than one early and between 1.03% and 1.24% had more than one late urethral complication. Regarding urethroplasty technique, complications mostly occurred in onlay flap urethroplasty with dorsal clitoral skin flap, while BMG with LM skin flap proved to be the most successful urethroplasty technique in our series. CONCLUSIONS: Metoidioplasty as a one-stage GAS is safe and viable and time-saving surgical approach that offers satisfactory functional outcomes with stand-up voiding in majority of transmen. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e404 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Marta Bizic More articles by this author Marko Bencic More articles by this author Borko Stojanovic More articles by this author Miroslav Djordjevic More articles by this author Expand All Advertisement PDF downloadLoading ...

Urethral Plate Substitution in Two-Stage Hypospadias Repair: Grafts Versus Flaps

BackgroundChoosing between flaps or grafts to substitute the urethral plate in 2-stage hypospadias repair has been a matter of debate with no consensus in the literature. Flaps have reliable blood supply that maybe theoretically less liable for strictures or contractures. Grafts are more versatile, which can be used in primary and recurrent cases when healthy local skin is deficient.In this report, our aim was to compare outcomes of grafts and flaps when used to substitute the urethral plate in two-stage repair of primary proximal hypospadias with ventral curvature. MethodsThis retrospective study included primary cases of hypospadias with significant curvature who underwent two-stage repair using either grafts or flaps to substitute the urethral plate in the first stage. Cases included in the study were divided into two groups according to the technique of substituting the urethral plate at the first stage of repair. During first part of the study period (2015 through 2018), we mostly used grafts to substitute the urethral plate (group A); later, we shifted to skin flaps (Group B) during the period 2019 through 2021. ResultsThe study included 37 boys with primary proximal hypospadias who underwent two-stage hypospadias repair. The meatus position was penoscrotal in 18, scrotal in 16, and perineal in three. Inner preputial graft was used to substitute the urethral plate in 18 cases (group A), while dorsal skin flaps were used in 19 (group B). Out of the 37 cases, 27 were available at follow-up after second stage (group A = 14; group B = 13). Follow up period ranged between 6 and 42 months (mean 19.7; median 18.5). Overall, 14 cases required reoperations for different indications: partial disruptions of distal part of the repair in six, closure of urethro-cutaneous fistula in six, and urethral strictures in two. The rate of complications was higher in group A (10 cases: 71%) compared to group B (4 cases: 31%) (Fisher exact test, p-value = 0.057). ConclusionGrafts were associated with higher complication rate than flaps when used to substitute the urethral plate in two-stage repair of proximal hypospadias with chordee. Type of Study and Level of EvidenceThis is non-randomized comparative study (level III evidence).

THE INFLUENCE OF ELECTROMAGNETIC RADIATION OF THE EHF BAND ON BLOOD OXIDATIVE METABOLISM UNDER MODELING THE ENGRAFTMENT OF A SKIN FLAP

The aim of the study was to evaluate the effect of electromagnetic radiation of the EHF band on the intensity of free radical oxidation processes and the activity of antioxidant enzymes in the blood of rats when modeling ischemia of the dorsal skin flap in vivo. The results of the experimental study showed that electromagnetic radiation inhibits lipid peroxidation in blood plasma due to activation of the overall antioxidant activity. In erythrocytes, the regulatory effect of irradiation on the prooxidant system was revealed by stimulating the enzymatic link of antioxidant protection.

Hyaluronic acid dermal filler injection increases the survival of rat dorsal skin flaps

Hyaluronic acid dermal filler injection increases the survival of rat dorsal skin flaps

Supplementation of high-dose ascorbic acid reduces necrosis on random dorsal skin flap in rats

BackgroundFlap necrosis due to ischemia-reperfusion injury remains a challenge to minimize in every flap procedure. Antioxidants are one of the alternatives developed to reduce free radicals formed from ischemia-reperfusion injury after the severance of blood vessels while also accelerating the wound healing process. Ascorbic acid (vitamin C) is the most widespread antioxidant available worldwide. ObjectiveTo determine the effect of high-dose ascorbic acid in reducing the occurrence of necrosis on random dorsal skin flaps in Wistar rats. MethodsAn double-blinded in-vivo experimental study was done on 36 Wistar rats undergoing a random dorsal skin flap procedure. The samples were divided into 2 groups. The intervention group samples were injected with high-dose ascorbic acid injection intraperitoneally at 300mg/kgBW per day for up to 7 days, while the control group samples were injected with normal saline. Variables analyzed were macrophage and malondialdehyde amount on the third day, fibroblasts amount on the seventh day, and distal flap necrosis on the seventh day. ResultHigher macrophage (14.56 vs. 4.78, p < 0.001) and fibroblasts amount (54 vs. 18, p < 0.001) were observed on the intervention group. Lower malondialdehyde amount (12 vs. 28, p < 0.001) was observed in the intervention group. There was a lower percentage of distal flap necrosis in the intervention group (11.9 vs. 36.2%, p < 0.001). ConclusionIntraperitoneal injection of high-dose ascorbic acid reduced the extent of distal flap necrosis on random dorsal skin flaps of Wistar rats.

Limited Efficacy of Adipose Stromal Cell Secretome-Loaded Skin-Derived Hydrogels to Augment Skin Flap Regeneration in Rats.

Insufficient vascularization is a recurring cause of impaired pedicled skin flap healing. The administration of adipose tissue-derived stromal cells' (ASCs') secretome is a novel approach to augment vascularization. Yet, the secretome comprised of soluble factors that require a sustained-release vehicle to increase residence time. We hypothesized that administration of a hydrogel derived from decellularized extracellular matrix (ECM) of porcine skin with bound trophic factors from ASCs enhances skin flap viability and wound repair in a rat model. Porcine skin was decellularized and pepsin-digested to form a hydrogel at 37°C. Conditioned medium (CMe) of human ASC was collected, concentrated 20-fold, and mixed with the hydrogel. Sixty Wistar rats were included. A dorsal skin flap (caudal based) of 3 × 10 cm was elevated for topical application of DMEM (group I), a prehydrogel with or without ASC CMe (groups II and III), or ASC CMe (group IV). After 7, 14, and 28 days, perfusion was measured, and skin flaps were harvested for wound healing assessment and immunohistochemical analysis. Decellularized skin ECM hydrogel contained negligible amounts of DNA (11.6 ± 0.6 ng/mg), was noncytotoxic and well tolerated by rats. Irrespective of ASC secretome, ECM hydrogel application resulted macroscopically and microscopically in similar dermal wound healing in terms of proliferation, immune response, and matrix remodeling as the control group. However, ASC CMe alone increased vessel density after 7 days. Porcine skin-derived ECM hydrogels loaded with ASC secretome are noncytotoxic but demand optimization to significantly augment wound healing of skin flaps.

Post-treatment with metformin improves random skin flap survival through promoting angiogenesis in rats.

Skin flap necrosis has been remained as an unsolved problem in plastic and reconstructive surgeries. Here, we explored the effects of metformin post-treatment on random skin flap survival in rats. An 8.00 × 2.00 cm dorsal skin flap was created in 24 rats and they were then divided into three groups (n = 8) including Control, metformin (Met) 50.00 mg kg-1 and Met 100 mg kg-1. All animals were administrated orally until seven days after flap surgery. Flap survival, the number of blood vessels and mast cells in the flap tissues were analyzed. Vascular endothelial growth factor (VEGF) expression levels in flap tissues was also determined using immunohistochemical methods. The percentage of survival area in Met 50.00 mg kg-1 and Met 100 mg kg-1 groups were significantly higher compared to control. The blood vessel density and the VEGF positive cells in the viable areas of flaps showed a significant increase in Met 50.00 mg kg-1 group compared to control group. The results of this study suggested that treatment with metformin, especially with low dose following skin flap surgery was effective in improving the flap survival and increasing the neovascularization in the flaps tissues of rats.

The Effect of Presurgical and Postsurgical Topical Tacrolimus on Pedicled Flap Survival in Rats: A Pilot Study.

Our previous rodent studies demonstrated significantly decreased full-thickness necrosis in pedicled dorsal skin flaps with topical tacrolimus as compared with petroleum jelly. Histologically, we found that topical tacrolimus was correlated with increased vascular growth in areas more susceptible to ischemic damage. The purpose of this study was to investigate the potential benefits of pretreatment with tacrolimus. By applying tacrolimus in advance of raising the dorsal skin flaps, we hoped to increase vascularity and thus increase the overall viability of the flaps. Twenty Sprague-Dawley rats were initially randomized to 4 groups based on timing of tacrolimus treatment (presurgical/postsurgical treatment): control/control (C/C), control/tacrolimus (C/T), tacrolimus/control (T/C), and tacrolimus/tacrolimus (T/T). Treatments consisted of 0.2 g of the control (topical petroleum jelly) and 0.1% topical tacrolimus to the rat dorsum twice per day. After 7 days of presurgical treatment, a cranially based dorsal skin flap measuring 3 × 10 cm was created. Two rats perished during surgery and were excluded for further analysis. Each rat was treated for a further 7 days and sacrificed. Two blinded reviewers marked the total skin flap area as well as areas of viable tissue, reversible ischemia, and full-thickness necrosis. Percentage areas were calculated using Fiji/ImageJ, and statistical analysis was performed in R. The average viable areas for C/C, C/T, T/C, and T/T were 31.4%, 31.9%, 35.6%, and 22.6%, respectively. The average reversible ischemic area for C/C, C/T, T/C, and T/T was 53.1%, 54.0%, 54.1%, and 71.5%, respectively. The average necrotic area for C/C, C/T, T/C, and T/T was 15.4%, 14.0%, 10.2%, and 5.9%, respectively. For areas of reversible ischemia, T/T arm had higher areas compared with C/T (P = 0.004) and T/C (P = 0.044). There was no significance between treatment arms for areas of viable and necrotic tissue. We observed higher areas of reversible ischemia for continuous tacrolimus treatment compared with only pre-tacrolimus application or post-tacrolimus application. This suggests that tacrolimus application before and after surgical insult may be associated with improved ischemic survival of the skin. Although we did not observe decreased areas of necrosis for tacrolimus treatment compared with control, this was likely due to the limited number of rats available in each arm to reach significance. Further study is needed to fully elucidate the encouraging trends that were observed.

Photobiomodulation effect in tumoral necrosis factor-alpha(TNF-α) on the viability of random skin flap in rats.

The aim of this study was to investigate the effect of red laser (660 nm) photobiomodulation (PBM) with different energies on tumor necrosis factor-alpha(TNF-α) expression for random skin flap viability in rats. Twenty-four Wistar rats were divided into three groups: sham group (SG), PBM laser group with an energy dose of 0.29 J (0.29G), and PBM laser group with an energy dose of 7.30 J (7.30G). A cranially based dorsal skin flap measuring 10 × 4 cm was raised and a plastic barrier was placed between the flap and its bed. PBM was applied in 3 timepoints: in the immediate postoperative period, in the 1st and in the 2nd postoperative days; the animals were euthanized on the 7th postoperative day. The assessments included: TNF-α expression of 3 different flap areas (proximal, medial and distal), by immunohistochemistry; percentage of skin flap necrosis area, by the paper template method. The statistical analysis was performed through the Kruskal-Wallis and Mann-Whitney tests, the level of significance adopted was 5% (p < 0.05). TNF-α expression was significantly lower for 7.30G in the proximal area, reduced for SG in the medial point, and larger for 7.30G in the distal area. The percentage of flap necrosis area was significantly reduced for 7.30G. Higher energy doses are more efficacious than lower energy doses for modulating TNF-α expression. PBM with an energy dose of 7.30 J was effective in reducing the expression of TNF-α and increase skin flap viability.

Cold Atmospheric Plasma, Platelet-Rich Plasma, and Nitric Oxide Synthesis Inhibitor: Effects Investigation on an Experimental Model on Rats

The evolution of reconstructive methods for defects of the human body cannot yet replace the use of flap surgery. Research is still preoccupied with the ideal techniques for offering the best chances of survival of the flaps. In our study, we investigated the effects of cold atmospheric plasma (CAP), N-nitro-L-arginine methyl ester (L-NAME), and platelet-rich plasma (PRP) injectable solutions on flap survival using an in vivo model. Twenty-four Wistar rats (four groups) had the McFarlane flap raised and CAP, L-NAME, and PRP substances tested through a single dose subcutaneous injection. The control group had only a saline solution injected. To the best of our knowledge, this is the first study that evaluated a CAP activated solution through injection on flaps. The flap survival rate was determined by clinical examination (photography documented), hematology, thermography, and anatomopathological tests. The image digital analysis performed on the flaps showed that the necrosis area (control—49.64%) was significantly lower for the groups with the three investigated solutions: CAP (14.47%), L-NAME (18.2%), and PRP (23.85%). Thermography exploration revealed less ischemia than the control group on the CAP, L-NAME, and PRP groups as well. Anatomopathological data noted the best degree of angiogenesis on the CAP group, with similar findings on the L-NAME and PRP treated flaps. The blood work did not indicate infection or a strong inflammatory process in any of the subjects. Overall, the study shows that the CAP activated solution has a similar (better) impact on the necrosis rate (compared with other solutions with known effects) when injected on the modified dorsal rat skin flap, and on top of that it can be obtained fast, in unlimited quantities, non-invasively, and through a standardized process.

Effects of different scar types on flap viability in a skin flap model: an experimental study.

The purpose of this study was to investigate the use of tissues with multiple traumas, scarred pedicles, and medial scarring as a flap. Forty-eight rats were randomly divided into four equal groups. The modified McFarlane flap was chosen as the flap model. In Group 1 (control), a dorsal skin flap was elevated and then sutured back into original position. In the other groups, a two-phase procedure was used. In Group 2 (pedicle incision), scar tissue was created with a skin incision at the prospective pedicle site of the flap and then sutured to its original site. In Group 3 (preconditioning), multiple full-thickness traumas were performed along the entire flap body, and in Group 4 (middle incision) scar tissue was created with a skin incision at the prospective middle region of the flap. Then, after 45 days, dorsal flaps were raised in all rats and then sutured back into position. Seven days later, flap survival was evaluated through microangiography and histological evaluation of flap segments. Histopathological examination included assessment of the number of vessels, necrosis, infiltration with polymorphonuclear leukocytes, edema, fibrosis, inflammation, increase in fibroblast activity, and neovascularization. The flap survival rates were 66.78% in Group 1, 68.05% in Group 2, 68.5% in Group 3, and 60.01% in Group 4. The flap survival rate was significantly lower in Group 4 (p &lt; 0.05). There was no significant difference in flap survival between Groups 1, 2, and 3. On microangiographic examination, the vascular network extended more distally and was densest around the scar line in Group 2. Vascularization was poorest in Group 4. On histological examination, the number of vessels tended to be greatest in Groups 3 and 4 but this was not significantly different between groups (p &lt; 0.05). The study findings showed that it may be possible to raise a flap from a previously mutilated site secondary to scar formation and multiple full-thickness traumas along the flap body. However, distal necrosis may occur in situations when the scar is positioned in the middle region of the prospective flap.

The Effect of Topical Tacrolimus on Pedicled Flap Survival: A Histological Analysis.

Our previous rodent study demonstrated significantly decreased full-thickness necrosis in pedicled dorsal skin flaps with topical tacrolimus as compared with petroleum jelly. The pathophysiology of tissue necrosis involves lymphatic congestion, followed by venous congestion and ultimately arterial insufficiency. Topical tacrolimus has been shown to increase growth of lymphatic collateral vessels and decrease lymphedema, potentially obviating one contributor to necrosis. The purpose of this study was to investigate the vascular and histological differences between these 2 groups to identify the etiology of our research findings. A 3 × 10-cm cranially based dorsal skin flap was raised and reinset on 22 Sprague Dawley rats. They were randomized to receive 0.2 g of either topical petroleum jelly or topical 0.1% tacrolimus ointment daily to the flaps. The rats were killed 7 days postoperatively. Two blinded reviewers marked the total flap area as well as areas of viable tissue, reversible ischemia, and necrotic tissue. Full-thickness biopsies of each area were taken from 2 randomly chosen animals in each group. Paraffin-embedded tissue was sectioned to generate hematoxylin and eosin-stained slides. Representative images of each area of the flap were taken less than 40× magnification using light microscopy. Arteries, veins, and lymphatics in the dermal layer were quantified under blinded conditions by a trained pathologist and calculated per cross-sectional area using Fiji software. The average area of the dorsal flaps in the control and tacrolimus groups was 22.5 and 23.9 cm2, respectively. Total necrotic area was significantly lower in rats receiving topical tacrolimus as compared with controls (P = 0.015). In the control cohort, average total number of vessels was 12.5, 6, and 0, in the areas of viable tissue, reversible ischemia, and necrosis, respectively. In the tacrolimus cohort, average total number of vessels increased was 20, 11.5, and 5.4, in the areas of viable tissue, reversible ischemia, and necrosis, respectively. On a histological level, topical tacrolimus is correlated with increased vascular growth in areas most susceptible for ischemic damage as compared with topical control. Future work is needed to investigate vascular biomarkers and increase the power of our study.

Clinical Effectiveness of Dorsal Branch Skin Flap of Proper Palmar Digital Artery with Distal Pedicle in Repairing of Fingertip Soft Tissue Defect: A 1-Year Prospective Study in a Chinese Tertiary Referral Teaching Hospital.

Background: Digital island flap remains among the most useful types of providing soft-tissues coverage for defect on the fingertip accompanied with underlying structures exposure. Nevertheless, its trends of functional and aesthetic issues such as the limited length of advancement and the limited flap size are the essential disadvantages. The main objective of the study was to assess the clinical effectiveness of dorsal branch skin flap of proper palmar digital artery with distal pedicle in repairing of fingertip soft tissue defect accompanied with underlying structures exposure. Methods: This is a 1-year prospective study, in which 21 patients (24 fingers) with traumatic fingertip skin and soft tissue defects had undergone emergency repair with dorsal skin flap of proper palmar digital artery with distal pedicle. The starting point of the dorsal proper palmar digital artery which is at the connection of distal interphalangeal joint with the digital midline was selected as the rotation point of the surgical skin flap, with an incision area of 1.1 cm × 1.4 cm-2.7 cm × 2.0 cm, the pedicle of 0.8-1.7 cm and disposition of 90°-120° to cover the fingertip. Results: All flaps had completely healed postoperatively. In 2 cases, tension blisters of the flap and partial necrosis were observed, which survived after change in dressing and rational administration vasodilator medication. Patients were followed up to 6 months. Favorable appearance and function were restored, and satisfactory recovery of the sensory functions of the fingers had been achieved. The two-point discrimination of skin flap with anastomosis of nerve could reach 4.5-9.4 mm (mean, 6.80 mm). Conclusions: Repairing the fingertip skin and soft tissue defect of 2nd-5th finger via primary surgical repair with dorsal distal pedicle or proper palmar digital artery skin flap is a good technique. The high survival rate of the flap, the favorable flap's appearance, and the satisfactory recovery of the sensory functions of the fingers are among the advantages of this reconstructive technique.