Recipient Blood Vessels Research Articles

Accelerating Patterned Vascularization Using Granular Hydrogel Scaffolds and Surgical Micropuncture.

Bulk hydrogel scaffolds are common in reconstructive surgery. They allow for the staged repair of soft tissue loss by providing a base for revascularization. Unfortunately, they are limited by both slow and random vascularization, which may manifest as treatment failure or suboptimal repair. Rapidly inducing patterned vascularization within biomaterials has profound translational implications for current clinical treatment paradigms and the scaleup of regenerative engineering platforms. To address this long-standing challenge, a novel microsurgical approach and granular hydrogel scaffold (GHS) technology are co-developed to hasten and pattern microvascular network formation. In surgical micropuncture (MP), targeted recipient blood vessels are perforated using a microneedle to accelerate cell extravasation and angiogenic outgrowth. By combining MP with an adjacent GHS with precisely tailored void space architecture, microvascular pattern formation as assessed by density, diameter, length, and intercapillary distance is rapidly guided. This work opens new translational opportunities for microvascular engineering, advancing reconstructive surgery, and regenerative medicine.

Comparison of Wound Healing Effect of Skin Micrograft Impregnated into Two Kinds of Artificial Dermis in a Murine Wound Model.

Skin MG was prepared from the skin of C57BL/6JJcl mice using Rigeneracons and administered onto Pelnac Gplus and Integra sheets. The amount of MG suspension impregnated in Pelnac Gplus and Integra was evaluated. Pelnac Gplus and Integra sheets combined with MG were applied to murine defects, and wound area, neoepithelium length, granulation tissue formation, and newly formed capillaries were compared with the control groups on days 7 and 14. The weight percentage of the MG absorbed by Pelnac Gplus and Integra was 88.8% ± 3.5% and 28.2% ± 7.0%, respectively (P < 0.05). In the in vivo experiment, the area of newly formed granulation tissue and both the number and area of newly formed capillaries in the PelnacG + MG group were significantly larger than those in the control group at 14 days after implantation (P < 0.05). Skin MG was successfully impregnated into Pelnac Gplus by simple administration but not into Integra. Administration of skin MG into the Pelnac Gplus promoted granulation formation and angiogenesis. Pelnac Gplus was more suitable than Integra in the combination therapy.

742 Quality of Operative Notes for Renal Transplant Surgery - Is Our Documentation Satisfactory?

Abstract Introduction Operation notes are essential in providing details of the procedure undertaken. The Royal College of Surgeons (RCS) Good Surgical Practice (GSP) guidelines recommend a checklist of 18 documentation items. Although these guidelines are useful, their broad and non-specific nature provides limitations to fields like transplantation, where additional information is needed. Ghoneima et al recommended transplant specific GSP checklist of 32 criteria for operation notes in transplantation. Our aim is to evaluate renal transplantation operation notes against these criteria. Method A retrospective audit of renal transplant operation notes was undertaken within Cardiff Transplant Unit between October 2020–2021. Notes were reviewed against new transplant specific GSP checklist. Results A total of 85 renal transplants were performed by 8 Consultant Surgeons. Sixty-two (73%) operation notes were hand-written and 23 (27%) electronically typed. Eleven standards had documentation compliance of &amp;gt;95% (e.g., date, surgeons’ names, recipient blood vessels, incision, allograft vascular anatomy, perfusion timings, closure, signature, etc). Some important transplant-specific information (e.g., primary renal disease, details of current renal replacement therapy, reperfusion characteristics, donor details (e.g., age, comorbidities), HLA mismatch, prosthesis (ureteric stent) details) were poorly documented (0–27% documentation compliance). Antibiotic and DVT prophylaxis documentation was also very poor (1–30%). Post-operative instructions did not record target blood pressure (0%) and postoperative potassium and ultrasound scan instructions were recorded in 65% of notes. Discussion Clear documentation is important for good surgical practice. This study highlights the need for a transplant-specific operation notes template, to not only improve the documentation but to standardize the key information recorded for every transplant performed.

Artery Reconstruction in Right Lobe Living Donor Liver Transplantation: Donor-Recipient Vessel Ratio Is Key to Choosing Recipient Artery.

The aims of this study were to investigate if recipient artery choice in right lobe living donor liver transplant affects postoperative complications and discuss solutions accordingly. Three hundred fourteen right lobe living donor liver transplantation patients were divided into 2 groups: 163 patients using right hepatic artery as the recipient vessel and 151 patients using left hepatic artery as the recipient vessel. Cases involving 2 recipient blood vessels or the use of other blood vessels as recipient vessels were excluded. Overall vascular embolism rate in both groups was 1.3%, and our complication rate was lower than those in previous studies. There was no significant difference in complication rate between the groups, but a significant difference in recipient/donor artery size ratio was noted. Although left hepatic artery's anatomical position makes it less affected by bile duct anastomosis and thus fewer postoperative complications, we believe that the ratio of the donor-recipient blood vessel size and the length of the anastomosis vessel stumps are the key factors that affect the outcome of the vascular anastomosis.

In Vivo Development of Fetal Pig Kidneys in Mature Monkeys under Clinically Approved Immunosuppressant Drugs

Controlling the immune response with only clinically approved immunosuppressant drugs is difficult in renal heterotransplantation from pigs to nonhuman primates. Moreover, to the best of our knowledge, no reports exist on the use of fetal pigs as kidney donors. This study aimed to compare the degree of transplant rejection between neonatal and fetal kidneys, with genetically unmodified pigs as donors and cynomolgus monkeys as recipients. The left kidneys of the recipient monkeys were removed, followed by transplantation of neonatal as well as fetal pig kidneys, which had undergone vascular anastomosis at the same site, into the retroperitoneum. Immunosuppression was performed with only US Food and Drug Administration-approved drugs. The fetal kidneys were transplanted into the omentum and para-aortic regions of cynomolgus monkeys. Consequently, the engraftment and development of the transplanted tissues were pathologically examined by sampling over time (twice in each experiment). An acute rejection was observed after a few weeks in neonatal renal grafts with vascular anastomosis. However, fetal pig kidneys were spared from rejection despite the administration of the same immunosuppressive protocol to the monkeys and the recipient blood vessels flowing into the fetal kidneys. The immunogenicity of fetal kidneys in pig–monkey renal heterotransplantation was lower than that of neonatal kidneys.

CD8 T Cells Target Antigen Cross-Presented by Bone Marrow Derived Cells to Induce Bystander Rejection of Grafts Lacking the Cognate Peptide-MHC

CD8 T cells play a key role in cancer immunotherapy and allograft rejection. However, it is not clear how they kill cells and tissues that do not have the agonist peptide-major histocompatibility complex (MHC) on their surface, as in the settings of MHC class I deficient tumors and indirect rejection of MHC-mismatched transplants. CD8 T cells might respond to agonist antigen cross-presented on hematopoietic cells, leading to a “bystander” rejection. Alternatively, they may recognize agonist antigen cross-presented on recipient endothelial cells and kill the tissue’s vital blood supply. The latter mechanism predicts that all non-vascularized grafts, grafts dependent on in-growth of recipient blood vessels, will be susceptible to CD8 T cell mediated indirect rejection. In contrast, we show here that non-vascularized transplants, bearing the same agonist antigen, are not universally susceptible to this rejection pathway. Non-vascularized skin, but not islet or heart tissue transplants were indirectly rejected by CD8 T cells. Furthermore, CD8 T cells were able to indirectly reject skin grafts when recipient MHC class I expression was restricted to bone marrow derived cells but not when it was restricted to radioresistant cells (e.g. endothelial cells). These findings argue against a major role for endothelial cell cross-presentation in killing of tissue that does not present the agonist peptide-MHC class I. Instead, the data suggests that cross-presentation by recipient hematopoietic cells underlies the CD8 T cell mediated killing of tissue that is unable to directly present the target peptide-MHC class I.

Clinical comparative study of free posterior tibial artery perforator flap and radial forearm free flap for head and neck reconstruction

Objective: To compare the clinical application results of the FPTF (free posterior tibial artery perforator flap) and RFFF (radial forearm free flap) for reconstruction of head and neck defects. Methods: A retrospective analysis of 27 cases treated with FPTF (19 males and 8 females, aged 14-69 years) and 24 cases with RFFF (11 males and 13 females, aged 22-69 years) for head and neck defect reconstruction at Beijing Tongren Hospital of Capital Medical University from January 2015 to December 2020 was conducted. Flap size, vascular pedicle length, matching degree of recipient area blood vessels, preparation time, total operation time, hospital stay, recipient area complications, donor area complications and scale-based patient satisfaction were compared between two groups of patients with FTPF and RFFF. SPSS 26.0 statistical software was used for statistical analysis. Results: There was no statistically significant difference between the two groups of patients in tumor T staging (P=0.38), primary sites (P=0.05) and mean flap areas ((53.67±29.84) cm2 vs. (41.13±11.08) cm2, t=-1.472, P=0.14). However the mean vascular pedicle length of FPTF was more than that of RFFF ((11.15±2.48)cm vs. (8.50±1.69)cm, t=-4.071, P<0.01). The donor sites of 4 patients in FPTF group could be sutured directly, while all the 24 patients in RFFF group received skin grafts from the donor sites. There was no statistically significant difference in the recipient area arteries between two groups of flaps (P=0.10), with more commonly using of the facial artery (RFFF: FPTF=21∶27), but there was significant difference in the recipient area veins (P<0.01), with more commonly using of the external jugular vein in RFFF (14/24) than FPTF (4/32) and the posterior facial vein in FPTF (27/32) than RFFF (9/24). There were 10 recipient complications and 3 donor complications in RFFF group; no recipient complication and 3 donor complications occurred in FPTF group. With patient's subjective evaluation of the donor site at 12 months after surgery, FPTF was better than RFFF (χ²=22.241, P<0.01). Conclusions: FPTF is an alternative to RFFF in head and neck reconstruction and has unique advantages in aesthetics and clinical application.

Intraoperative transit-time ultrasonography combined with FLOW800 predicts the occurrence of cerebral hyperperfusion syndrome after direct revascularization of Moyamoya disease: a preliminary study.

Cerebral hyperperfusion syndrome (CHS) is a common complication after direct bypass surgery in patients with Moyamoya disease (MMD). Since preventive measures may be inadequate, we assessed whether the blood flow difference between the superficial temporal artery (STA) and recipient vessels (△BF) and the direct perfusion range (DPR) are related to CHS. We measured blood flow in the STA and recipient blood vessels before bypass surgery by transit-time probe to calculate △BF. Perfusion changes around the anastomosis before and after bypass were analyzed with FLOW800 to obtain DPR. Multiple factors, such as △BF, DPR, and postoperative CHS, were analyzed using binary logistic regression. Forty-one patients with MMD who underwent direct bypass surgery were included in the study. Postoperative CHS symptoms occurred in 13/41 patients. △BF and DPR significantly differed between the CHS and non-CHS groups. The optimal receiver operating characteristic (ROC) curve cut-off value was 31.4ml/min for ΔBF, and the area under the ROC curve (AUC) was 0.695 (sensitivity 0.846, specificity 0.500). The optimal cut-off value was 3.5cm for DPR, and the AUC was 0.702 (sensitivity 0.615, specificity 0.750). Postoperative CHS is caused by multiple factors. △BF is a risk factor for CHS while DPR is a protective factor against CHS.

Feasibility and Reliability of Microvascular Reconstruction in the Vessel-depleted Previously Operated Neck.

Background:Microvascular reconstruction of defects in the head and neck has always been a challenge in patients who have undergone previous neck dissection, owing to the prior resection of potential recipient blood vessels used for free flap perfusion.Objective:The objective of the study is to evaluate the reliability and safety of free flap reconstruction in patients who have had previous neck dissection.Materials and Methods:Twenty-four free flaps were performed in 22 patients with a previous history of neck dissection for head-and-neck squamous cell carcinoma. These included patients who underwent salvage surgery for recurrent cancer as well as patients undergoing secondary reconstruction following previous oncological resections. Flap includes 12 radial forearm free flaps, 5 fibula flaps, 1 rectus abdominis flap, and 6 anterolateral thigh flaps.Results:In cases with the previous history of selective neck dissection, recipient vessels on the ipsilateral/same side of the previously operated neck were used, while contralateral vessels were used in patients with a history of modified radical or radical neck dissection. Vein grafts were not necessary, except for one case. In our series, we did not have any flap loss or considerable increase in operative time.Conclusions:Free flap reconstruction of head-and-neck defects is highly successful in patients with a history of previous neck dissection, despite a relative scarcity of recipient blood vessels. Careful planning and relying on flaps with a long vascular pedicle obviates the need to perform a suitable vein graft. In our present series, careful planning and the right choice of a free flap with a long vascular pedicle contributes to the absence of free flap failure. In our experience, previous neck dissection should not be considered as a contraindication to microvascular reconstruction of previously operated oncologic defects.

Reconstruction of a Tibial Defect With a Previously Fractured Fibula Including the Fractured Segment as a Free Osteoseptocutaneous Flap

Reconstruction of major bone defects using free fibular transfer provides a good biological option in unsound situations. Most authors recommend selection of the recipient blood vessels outside the zone of injury to achieve successful free fibular transfer. Occasionally, in polytraumatized patients, the surgeon has to use a previously fractured fibula as a graft, with increased risk of inclusion of the injury zone that may lead to failure. We report a rare case of successful reconstruction of a large tibial defect using a previously fractured fibula as a free osteoseptocutaneous flap. The innovative point in our case is the inclusion of the fracture site within the utilized segment, which to our knowledge has never been reported. As long as the microsurgical principles are adhered to, the effect of the zone of injury on the graft viability should not be overwhelming.

Erfolgreiche Behandlung einer subglottischen Trachealstenose mittels Mukosa-Radialisfaszien-Lappen

Short-segment tracheal stenosis is often treated by segmental resection and end-to-end anastomosis. Longer-segment stenosis can sometimes be treated using dilation, laser therapy, bronchoscopic stent insertion and segmental resection and reconstruction. Long-segment restenosis with a buildup of scar tissue due to successful resection surgery in the past represents a particular therapeutic challenge and a sufficiently vascularized transplant may be the only option. We describe the case of a 37-year-old patient who underwent a tracheal reconstruction using a mucosa-lined radial forearm flap. Subsequent to a traumatic laryngotracheal fracture, long-term ventilation and multiple surgical interventions, the patient had developed a functionally relevant subglottic stenosis (5.5 cm). Following longitudinal anterior resection of the trachea 1 cm above and below the stenosis, a Dumon® stent was inserted. Simultaneously, a radial forearm fascia flap was harvested, as were two full-thickness buccal mucosa grafts, which were sutured onto the subcutaneous tissue and fascia of the forearm flap. Beginning caudally, the mucosa-lined flap was then sutured, air-tight, into the anterior tracheal defect with the mucosa facing the lumen. Finally, end-to-end anastomosis connected the blood vessels of the radial forearm flap to the recipient blood vessels in the neck. The patient was successfully extubated after 24 h and discharged after 5 days. A postoperative CT scan revealed optimal placement of the stent and the patient's speech and breathing were sufficiently re-established. The stent was removed bronchoscopically 6 weeks after surgery. Examinations during the 6-month follow-up period showed that the diameter of the reconstructed airway was retained and the patient remained symptom-free.

Markedly Decreased Blood Perfusion of Pancreatic Islets Transplanted Intraportally Into the Liver

Experimental studies indicate low revascularization of intraportally transplanted islets. This study aimed to quantify, for the first time, the blood perfusion of intrahepatically transplanted islets and elucidate necessary factors for proper islet graft revascularization at this site. Yellow chameleon protein 3.0 islets expressing fluorescent protein in all cells were transplanted. Graft blood perfusion was determined by microspheres. The vascular density and relative contribution of donor blood vessels in revascularization was evaluated using islets expressing green fluorescent protein under the Tie-2 promoter. Blood perfusion of intrahepatic islets was as a mean only 5% of that of native islets at 1-month posttransplantation. However, there was a marked heterogeneity where blood perfusion was less decreased in islets transplanted without prior culture and in many cases restored in islets with disrupted integrity. Analysis of vascular density showed that distorted islets were well revascularized, whereas islets still intact at 1-month posttransplantation were almost avascular. Few donor endothelial cells were observed in the new islet vasculature. The very low blood perfusion of intraportally transplanted islets is likely to predispose for ischemia and hamper islet function. Since donor endothelial cells do not expand posttransplantation, disruption of islet integrity is necessary for revascularization to occur by recipient blood vessels.

Thrombospondin-1: An Islet Endothelial Cell Signal of Importance for β-Cell Function

OBJECTIVELoss of thrombospondin (TSP)-1 in pancreatic islets has been shown to cause islet hyperplasia. This study tested the hypothesis that endothelial-derived TSP-1 is important for β-cell function.RESEARCH DESIGN AND METHODSIslet function was evaluated both in vivo and in vitro. Messenger RNA and protein expression were measured by real-time PCR and Western blot, respectively. The role of endothelial-derived TSP-1 for β-cell function was determined using a transplantation design in which recipient blood vessels either were allowed to grow or not into the transplanted islets.RESULTSTSP-1–deficient mice were glucose intolerant, despite having an increased β-cell mass. Moreover, their islets had decreased glucose-stimulated insulin release, (pro)insulin biosynthesis, and glucose oxidation rate, as well as increased expression of uncoupling protein-2 and lactate dehydrogenase-A when compared with control islets. Almost all TSP-1 in normal islets were found to be derived from the endothelium. Transplantation of free and encapsulated neonatal wild-type and TSP-1–deficient islets was performed in order to selectively reconstitute with TSP-1–positive or –negative blood vessels in the islets and supported that the β-cell defects occurring in TSP-1–deficient islets reflected postnatal loss of the glycoprotein in the islet endothelial cells. Treatment of neonatal TSP-1–deficient mice with the transforming growth factor (TGF)β-1–activating sequence of TSP-1 showed that reconstitution of TGFβ-1 activation prevented the development of decreased glucose tolerance in these mice. Thus, endothelial-derived TSP-1 activates islet TGFβ-1 of importance for β-cells.CONCLUSIONSOur study indicates a novel role for endothelial cells as functional paracrine support for pancreatic β-cells.

Stromal Vascular Fraction From Adipose Tissue Forms Profound Vascular Network Through the Dynamic Reassembly of Blood Endothelial Cells

Tremendous efforts have been made to establish effective therapeutic neovascularization using adipose tissue-derived stromal vascular fraction (SVF), but the efficiency is low, and underlying mechanisms and their interaction with the host in a new microenvironment are poorly understood. Here we demonstrate that direct implantation of SVF derived from donor adipose tissue can create a profound vascular network through the disassembly and reassembly of blood endothelial cells at the site of implantation. This neovasculature successfully established connection with recipient blood vessels to form a functionally perfused circuit. Addition of vascular growth factors to the SVF implant improved the efficiency of functional neovasculature formation. In contrast, spheroid culture of SVF before implantation reduced the capacity of vasculature formation, possibly because of cellular alteration. Implanting SVF into the mouse ischemic hindlimb induced the robust formation of a local neovascular network and salvaged the limb. Moreover, the coimplantation of SVF prevented fat absorption in the subcutaneous adipose tissue graft model. Freshly isolated SVF can effectively induce new vessel formation through the dynamic reassembly of blood endothelial cells and could be applied to achieve therapeutic neovascularization for relieving ischemia and preventing fat absorption in an autologous manner.

Angiostatic factors normally restrict islet endothelial cell proliferation and migration: implications for islet transplantation

New blood vessel formation in transplanted islets occurs within 7-14 days post-transplantation through both the expansion of donor islet endothelium and ingrowth of blood vessels from the implantation organ. However, several studies indicate that although the islets attract recipient blood vessels, the formed intra-islet vascular network is insufficient, which affects islet post-transplant function. This study aimed to develop an in vitro model to investigate the migration and proliferation properties of isolated liver and islet endothelium.Rat islet or liver endothelium was purified using Bandeiraea simplicifolia(BS-1)-coated Dynabeads. The liver endothelium displayed an increased migration and proliferation to islet-conditioned medium. These effects were fully prevented by adding a neutralizing vascular endothelial growth factor (VEGF)-antibody. In contrast, islet-produced VEGF failed to induce islet endothelial cell migration and only had marginal effects on islet endothelial cell proliferation.These properties could, however, be activated through blocking the effects of either endostatin, thrombospondin-1 or alpha(1)-antitrypsin. In conclusion, VEGF may attract recipient blood vessels towards intrahepatically transplanted islets,but intra-islet vascular expansion is hampered by angiostatic factors present within the islets and the islet endothelium. Inhibition of angiostatic factors early after transplantation may provide a strategy to restore the islet vascular network and improve islet graft function.

Thoracoepigastric Flap for the Closure of an Elbow Defect in an Intravenous Drug Abuser: A Case Report and Review of Literature

The reconstruction of large soft tissue defects of the upper extremity is a challenging problem. Although free tissue transfer in a single stage is preferred, the recipient blood vessels usually determine the outcome. Due to venous occlusion from repeated intravenous drug abuse, the use of a thoracoepigastric flap to cover a complex wound of the elbow is reported.

Microvascular reconstruction after previous neck dissection.

Microvascular reconstruction of defects in the head and neck is more challenging in patients who have undergone a previous neck dissection, owing to prior resection of potential cervical recipient blood vessels used for free flap perfusion. To evaluate the reliability and safety of free flap reconstruction in patients with previous neck dissection. Sixty free flaps were performed in 59 patients with a medical history of neck dissection for head and neck cancer. This included patients undergoing salvage surgery for recurrent cancer as well as patients undergoing secondary reconstruction of cancer surgery-related defects. Flap selection included 25 radial forearm flaps, 20 fibula flaps, 7 rectus abdominis flaps, 7 subscapular system flaps, and 1 iliac crest flap. Recipient vessels were used in the field of previous neck dissection in approximately half the patients with previous selective neck dissection, while contralateral recipient vessels were always used in patients with a history of modified radical or radical neck dissection. Vein grafts were not necessary in any cases. One arterial anastomosis that was created under excessive tension required urgent reoperation and revision, but there were no cases of free flap failure. Free flap reconstruction of the head and neck is highly successful in patients with a history of neck dissection, despite a relative paucity of potential cervical recipient blood vessels. Heavy reliance on free flaps with long vascular pedicles obviated the need to perform vein grafts in the present series, probably contributing to the absence of free flap failure. Previous neck dissection should not be considered a contraindication to microvascular reconstruction of the head and neck.

“Chain-link” combined tissue transfer for the reconstruction of the mandible

We describe a procedure for “chain-link” combined tissue transfer connecting the vascular pedicle of a deep circumflex iliac flap with that of a forearm flap after wide resection of the mandible. Combination of these flaps facilitated the reconstruction of the defect in both intra- and extraoral soft tissue and the mandibular bone. This method is useful when cervical recipient blood vessels are limited due to the wide resection of the primary tumor and radical neck dissection.

The role of skin dendritic cells in the initiation of human immunodeficiency virus infection

Human immunodeficiency virus (HIV) can be transmitted by accidental puncture with needles containing HIV-contaminated blood. However, the molecular and cellular interactions that occur between HIV and cells of the skin following percutaneous needlestick injury are unknown. Direct inoculation of exogenous virus into recipient blood vessels of the dermis is possible. In addition, skin dendritic cells (DC; e.g., epidermal Langerhans cells, dermal DC, lymphatic veiled cells) may also play a role in the initiation of HIV infection. Evidence to suggest that DC are important in primary HIV infection is derived largely from in vitro experiments and animal models. For example, cutaneous DC can be infected with HIV in vitro, can capture HIV on their cell surface (independent from DC infection), and can efficiently transmit HIV to CD4+ T cells. In recent in vivo experiments using rhesus macaques, submucosal DC were the first cells infected following intravaginal exposure to simian immunodeficiency virus (SIV). In this review, I discuss the possible immunologic events that occur within skin and draining lymph nodes following needlestick exposure to HIV-contaminated blood, with a particular emphasis on DC-HIV interactions.

Management of Associated Soft-Tissue Injury

Initially, soft-tissue injuries associated with vascular trauma require management according to the general surgical principles of wound care. Antimicrobial prophylaxis should be instituted. The mechanism and extent of injury must be determined, and debridement and irrigation should be completed in the operating room with the intent to preserve vital structures, decrease bacterial contamination, and render the wound free of devitalized tissue. Prompt coverage of exposed vascular repairs is vital in order to minimize the chance for infection and to protect the repair from desiccation and subsequent trauma. Early primary closure of heavily contaminated wounds can have disastrous results. Therefore, questionable wounds should be managed by delayed primary closure after repeated irrigation and debridements, with the definitive decision as to the timing of wound closure being based on quantitative cultures. The plastic and reconstructive surgeon can aid the vascular surgeon in the primary or secondary closure of such wounds by bringing healthy, vascularized muscle to cover the vascular repair. Vascularized muscle has proved superior in the coverage and healing of contaminated wounds. If conditions permit, this can be most readily accomplished by transfer of local muscle. Musculocutaneous flaps are of special value in cases that require increased durability or where extended coverage is necessary. With either of these flap techniques, the surgeon must be thoroughly familiar with the anatomy, blood supply, and function of the local muscles. Free-tissue transfer is to be utilized when local tissue is severely damaged in a way that precludes the use of adjacent muscle or myocutaneous flaps. Strict adherence to the principles and techniques of microsurgery, thorough evaluation of the zone of injury and recipient blood vessels, and understanding of the principles governing local muscle transfer are essential for a successful outcome.