Risk assessment and management in hand and facial tissue transplantation.

PURPOSE: Since hand and facial tissue transplantation are new treatments, risk data must be derived from early reports of the few cases done to date combined with extrapolations from other procedures with similar risks. This manuscript summarizes data from both sources including eight separate studies that measure the real and perceived risks associated with hand and facial tissue transplantation. METHODS: Real Risks: Several large clinical studies describing risk data from kidney transplant recipients (10-years experience) and risk data from 49 human hand transplants in 33 recipients (>10 years experience) were reviewed. Perceived Risks: Over 500 subjects with different life experiences (facially disfigured, amputees, laryngectomees, kidney transplant recipients, transplant and reconstructive surgeons, and controls) were surveyed using a standardized and validated risk assessment instrument. RESULTS: Real Risks: Contrary to earlier estimates the risks of acute rejection are higher (80-85%) while the risks of chronic rejection (<5%) and other complications are lower than previously reported. Perceived Risks: Despite different life experiences, those questioned would accept similar amounts of risk to receive different types of transplant procedures (hand, foot, face, larynx, and kidney) but all would accept the most risk for a facial tissue transplant. Kidney transplant recipients, who live with the risks of immunosuppression, would accept the most risk while facially disfigured individuals and reconstructive surgeons, who have real-life experience with facial disfigurement, would accept the least. CONCLUSIONS: These studies contribute to the growing body of risk data necessary for moving hand and face transplantation into mainstream medicine.

Glabrous skin grafts for plantar defects.

The principle of reconstructing like to like has been a long-standing and useful concept for plastic surgeons. One arena in which this concept has not been put to its full use is that of reconstructing soft tissue deficits of the sole of the foot. Most commonly, plantar defects that are to be skin grafted are reconstructed with split- or full-thickness, nonglabrous skin grafts. Nonglabrous skin grafts have significant disadvantages when used for reconstruction of plantar defects. These include painful hyperkeratotic build up at the periphery of the skin grafts, craters, contractures, and tight subgraft fibrosis. Glabrous skin grafting has been applied widely for coverage of smaller defects in the hand and has yielded superior results with improved function and sensation, more normalcy of appearance, and increase durability. The concept of reconstructing plantar defects by this method has probably been impeded by the vague and erroneous, but broadly held, belief that donor-site healing in the foot would be problematic, that is, significant potential for excessive scarring, pain, and functional deficit. The long-standing use of glabrous skin grafts for plantar defects in this unit, however, confirms the desirability, functional advantage, and minimal morbidity of this technique.

Microcirculatory changes following different temperature washouts in a free flap model.

In spite of the extensive experimental work on vascular washout in free flap surgery, an optimal temperature for the washout solution has not been established. This study was designed to determine the effect of the washout solution temperature on the degree to which the microcirculation is cleared of blood. The cremaster muscle flap in the rat was used, in which the microcirculation can be directly viewed and the presence of blood and perfusion parameters within various vessels can be measured during and after washout. Washout was started with a single, high-pressure infusion and continued at 130 mmHg for 15 minutes. The temperature of the washout solution was either 2-3, 20-22, or 35 degrees C. In all three groups, washout cleared the microcirculation almost completely within the first minute. However, we observed that a cold or room temperature washout cleared the microcirculation more completely than a warm washout did. The temperature of the washout solution did not effect post washout capillary perfusion and/or arterial diameters.

Effect of low dose aspirin on thrombus formation at arterial and venous microanastomoses and on the tissue microcirculation.

In free flap/replantation surgery, failure is usually associated with thrombotic occlusion of a microvascular anastomosis (risk zone I) or, on occasion, flow impairment in the microcirculation of the transferred or replanted tissue (risk zone II). The objective of this study is to describe the effect of low dose aspirin on blood flow at both risk zones in microvascular surgery. Risk zone I: In rat femoral arteries and veins, thrombus formation was measured at the anastomoses using transillumination and videomicroscopy. Forty male Wistar rats were assigned in equal numbers to four groups: either arterial or venous injury with either aspirin (5 mg/kg systemically) or saline treatment. We found that aspirin significantly reduces thrombus formation at the venous anastomosis (p = 0.001). Risk zone II: In the isolated rat cremaster muscle downstream from an arterial anastomosis, we measured capillary perfusion, arteriolar diameters, and the appearance of platelet emboli for 6 hours in the muscle microcirculation. Sixteen male Wistar rats in two equal groups received either aspirin (5 mg/kg systemically) or saline. We found that in aspirin-treated animals, capillary perfusion is significantly (p = 0.002) improved, whereas arteriolar diameters and emboli only slightly increased. In conclusion, low dose aspirin inhibits anastomotic venous thrombosis and improves microcirculatory perfusion in our rat model. These studies provide quantitative data confirming and clarifying the beneficial effects of low dose aspirin in microvascular surgery.

Prefabricated jejunal free-tissue transfer for tracheal reconstruction: an experimental study.

Reconstruction of long-segment tracheal defects is a problem for the reconstructive surgeon. Difficulties arise with the use of prosthetic materials because of their propensity for infection and extrusion. Autologous tissue is limited by poor structural characteristics and technical complexity. We propose a simple composite bioprosthesis that, through a process of prefabrication and subsequent neovascularization, may provide a functional tracheal analogue superior to existing forms of reconstruction. Ten rats had composite flaps constructed by combining an isolated, perfused, mucosectomized segment with an outer covering of a ring-reinforced woven Dacron vascular graft. This unit remained in the intraabdominal milieu for 20 days and was then inspected for viability, incorporation of jejunum and graft, flexibility, and tolerance to negative pressure. Seven experimental animals survived the initial phase. The jejunal bioprostheses in all cases tolerated negative pressures to -200 mmHg, rotation of 180 degrees, and flexion to 90 degrees without collapse of the graft segments. Vascular casts and standard histologic examination showed neovascularization of the Dacron graft and dense fibrovascular ingrowth into the interstices of the graft. We conclude that prefabrication utilizing autologous and prosthetic components to create a single axial flap for transfer is a feasible solution to long-segment tracheal reconstruction. Neovascularization permeates the full thickness of the prosthetic component and is accompanied by dense fibrous ingrowth during the delay period. This neotracheal analogue also possesses structural characteristics similar to those of the native trachea and a durable submucosal layer that can support ingrowth of epithelium.

Can varying flow velocity across an arterial anastomosis prevent thromboembolic injury?

In this study, simulated "poor" repairs applied to transverse incisions in the iliac arteries of 40 rats were the basis for comparing the effect of variations in blood flow on thromboembolism. Using vital microscopy and digital image processing, we performed 2 experiments. In the first experiment (n = 20), the reduction of post-repair blood flow by approximately 50% resulted in an 83% reduction in the total number of emboli appearing in the microcirculation of the cremaster muscle distal to the repair. In the second experiment (n = 20), the same reduction in blood flow typically resulted in larger repair-site thrombi which required significantly more time to grow to their maximum size. We conclude that reducing pedicle artery blood flow to approximately half in our rat model during reperfusion can protect the downstream microcirculation from embolic injury without increasing the incidence of thrombotic occlusion.

Microsurgery without a microscope: laboratory evaluation of a three-dimensional on-screen microsurgery system.

In microvascular surgery, procedures may be both technically and physically demanding. Precise movements sustained over long hours in addition to typically compromised surgeon and assistant positioning lead quickly to physical and mental fatigue. Many of the positioning problems encountered are related to the fact that the eyes of the surgeon must be continually fixed to the microscope eyepieces. This study explores a possible solution: a microscope system that eliminates the need to view the operative field through the microscope eyepieces. A Three-dimensional On-screen Microsurgical System (TOMS) was used and contrasted with conventional operative microvascular surgery in the laboratory setting. The surgeon's comfort, his ability to instruct microsurgical technique, pertinent technological performance, and the procedure itself were evaluated using a standardized questionnaire. Based on data collected in this study, we conclude that divorcing the surgeon's eyes from the microscope eyepieces using the TOMS may make prolonged microvascular procedures less physically demanding and may increase the comfort level of both the surgeon and his assistant, although refinements to the technology are required.

Pedal or peroneal bypass: which is better when both are patent?

PURPOSE: We compared autogenous vein pedal and peroneal bypasses, focusing on extremities that could have a bypass to either artery. METHODS: From 1985 to 1993 we performed a total of 175 pedal and 77 peroneal autogenous vein bypasses for rest pain (n = 75, 30%) and tissue loss (n = 177, 70%). One hundred ninety-six (78%) in situ saphenous vein and 56 (22%) reversed or composite vein bypasses were performed. One hundred fifty-two of these 252 bypasses were performed in extremities with both the pedal and peroneal arteries patent by arteriography. The vascular surgeon chose to perform 99 pedal and 53 peroneal vein bypasses in these 152 extremities. RESULTS: The angiogram score of the outflow arteries were similar for pedal and peroneal bypasses with the Society for Vascular Surgery and the International Society for Cardiovascular Surgery and modified scoring systems. At 2 years the primary and secondary patency rates for pedal bypasses (70% and 77%) were not significantly different compared with those for peroneal bypasses (60% and 72%). Limb salvage rates at 2 years were similar for pedal and peroneal bypasses for all patients (74% and 73%), patients with both pedal and peroneal arteries patent (83% and 72%), diabetics (76% and 66%), and patients with tissue necrosis (77% and 71%). CONCLUSIONS: Pedal and peroneal artery bypasses with equivalent angiogram scores have similar long-term graft patency and limb salvage. The choice between pedal or peroneal artery bypass should be based on the quality of vein and the surgeon's preference.

Microcirculation research, angiogenesis, and microsurgery.

Angiogenesis, the formation of new blood vessels, is essential to a variety of normal and pathologic processes such as wound healing and tumor growth. In microsurgery the development of new vessels between the transferred tissue and the recipient bed is critical to the final outcome of the reconstruction. Several experimental models have been previously developed to study angiogenesis and the effect that new substances have on regulating this process, but they lack the ability to make quantitative measurements. Therefore, we have developed an animal model using the homozygous (hr/hr) hairless mouse ear; by using intravital microscopy and computer-assisted analysis, angiogenesis can be quantitatively measured. Using this model we showed that basic fibroblast growth factor and transforming growth factor beta significantly increased total vessel length by 32% and 63%, respectively, during 20 days following subcutaneous injection. In this paper the importance of angiogenesis research to reconstructive microsurgery is presented and discussed.

Direct visualization and measurements of wound neovascularization: application in microsurgery research.

Neovascularization or angiogenesis is an essential yet poorly understood component of the healing process. In wound healing research, there is a lack of models enabling quantitative and continuous measurements of wound neovascularization. The hairless mouse ear wound model permits quantitative measurements of wound epithelialization and neovascularization continuously throughout the healing process. On the ears of male homozygous (hr/hr) hairless mice, standardized circular full thickness dermal wounds are produced; then, using vital microscopy, these two processes are directly viewed and measured at day 0 and every third day thereafter until these are complete. This model system and its application to clinically relevant situations are reviewed.

Microcirculatory consequences of microvascular surgery.

Although free tissue transfer success has been greatly improved by developments in operating microscopes, microsutures, microinstruments, and technique, free flap and replant failure remain a significant problem under certain adverse circumstances. The nature of these failures is often multifactorial and remains poorly understood. A greater understanding of the processes involved would provide the potential for greater pharmacological control of any adverse conditions prevailing and would thus offer the prospect of more effective adjunctive therapy in the presence of such adverse conditions. Research endeavors in this area have been hindered by the absence of good research models. The isolated rat cremaster muscle model is a recently developed model that simulates the conditions of free tissue transfer. Using this model, both thrombus formation and numerous microcirculatory parameters can be measured. The microcirculatory parameters studied to date include the formation of thromboembolism, capillary perfusion, vessel diameters, red blood cell velocity, leukocyte-endothelium interaction, and microvascular leakage. The isolated rat cremaster muscle model addresses many of the shortcomings of earlier research models and offers the promise of answering at least some of the many unanswered questions relating to free flap and replant failure.

Microsurgical adjuncts in salvage of the ischemic and diabetic lower extremity.

Revascularization of distal occlusive disease in the diabetic has been markedly enhanced by microsurgical techniques. Extremely small, heavily calcified vessels are able to be reliably reconstructed using microsurgical techniques and high magnification. Additionally, revascularization followed by microsurgical free tissue transfer has proven to be a valuable alternative to amputation in patients with major soft-tissue loss, or bony or tendon lesions requiring soft-tissue reconstruction. Although metabolic risks are potentially high, we have experienced a very low morbidity and mortality with a thorough medical work-up and follow-through in conjunction with these major procedures. It is our expectation that judicious application of microsurgical techniques in treatment of the ischemic diabetic lower extremity will continue to improve the chances for long-term bipedal ambulation in this patient population.

Oral commissure expansion prosthesis.

An expansion prosthesis to stretch commissures and fibrotic muscles is often essential for patients recovering from head and neck trauma or burns. The prosthesis is easily made in one appointment using Triad resin and a 7 mm expansion screw. Depending on the frequency of use, varying degrees of opening of the jaws can be obtained. The prosthesis is inexpensive to make and can easily be modified as needed. It is convenient for use because the patient controls the pressure that is applied by the prosthesis.

Refinements in free flaps for head and neck reconstruction.

The decade of adolescence of microsurgical techniques of head and neck reconstruction has led to a further clarification of the indications and methods for microsurgical reconstruction of head and neck defects. A review of the defects and the variety of flaps available for reconstruction leads to an increased understanding of the advantages and disadvantages of these various methods. When assessing a defect in the head and neck for microsurgical reconstruction, the surgeon should consider the various advantages of the flap to be used and weigh them against the disadvantages. The specialty has long since passed the point when one or two donor flaps could be considered to answer all of the reconstructive questions. We must now thoughtfully consider all the available options before settling on a course of treatment.

Utility of inframalleolar arterial bypass grafting.

Sixty-five patients received 68 inframalleolar arterial grafts for severe rest pain, foot ulceration, or gangrene. Patients were elderly with an average age of 68 years (median 72); most had several operative risk factors. Reversed saphenous vein grafts were used early, but most conduits were in situ vein grafts. The recipient vessel was the dorsalis pedis artery in 39 patients, the posterior tibial in 27, and tarsal branches in two. Preoperative angiography was routinely performed with biplanar and digital arterial techniques, but in nearly a third a suitable bypass vessel was not identified preoperatively. When vessels were identified there was usually only a single patent artery suitable for bypass grafting below the knee. There were five postoperative deaths (7.6%). Eight grafts (11%) required early revision for thrombosis or retained valve, and six were salvaged and remained patent. Poor vein quality appeared responsible for the two early failures. Six late graft occlusions occurred from 4 to 39 months (mean 14 months). Three of these patients had no recurrence of their ulceration, but two required amputation, and one has continued rest pain. One additional amputation was required in a patient with a patent graft. Eleven late deaths (16%) occurred (nine with patent grafts) primarily of cardiac causes.

Thin cutaneous flap for intra oral reconstruction: the dorsalis pedis free flap revisited.

The dorsalis pedis flap provides thin, hairless tissue for a variety of intra oral defects. Due to concerns for the donor site, reconstructive surgeons have largely overlooked this flap, despite its numerous desirable qualities. The paper focuses on the anatomy of the first dorsal metatarsal artery and techniques which insure the preservation of adequate flap vascularity. The prevention of donor site complications centers around meticulous attention to the placement of skin grafts, with a secure tie-over dressing and the use of a posterior splint. Patients are allowed to ambulate in the early postoperative period only when venous compression is provided with an ace bandage. Vigorous attention to detail on reconstructing the foot has minimized donor site complications. The dorsalis pedis flap continues to be an important method of reconstruction in our armamentarium of free tissue donor sites.

Microsurgical reattachment of totally amputated ears.

At a time when microsurgical reattachment of amputated limbs is commonplace, successful reattachment of total ear amputations is rare. Avulsed vessels, small diameters (0.3 to 0.7 mm), and technical difficulties provide primary obstacles. Three clinical cases of ear reattachments are presented which encompass the clinical spectrum of an uncomplicated success, a salvage of an impending failure, and a late failure due to venous thrombosis. In all cases there was difficulty with identification of vessels, with differentiation of arteries from veins, and in the performance of venous anastomoses. Vein grafts were necessary in two of the three patients. Anticoagulation was essential in alleviating venous thrombosis. Medicinal leeches (Hirudo medicinalis) were used to salvage one case with venous thrombosis. Despite the technical difficulties and long operative times, successful microvascular reattachment of an amputated ear is superior to any other means of reattachment or reconstruction.

The osteocutaneous scapular flap for mandibular and maxillary reconstruction.

Microfil injections in 8 cadavers and clinical experience with 26 patients have demonstrated a reliable blood supply to the lateral border of the scapula based on branches of the circumflex scapular artery. This tissue has been used successfully for reconstruction of a variety of defects resulting from maxillectomy and mandibular defects from cancer and benign tumor excisions. Advantages of this tissue over previous reconstructive methods include the ability to design multiple cutaneous panels on a separate vascular pedicle from the bone flap allowing improvement in three-dimensional spatial relationships for complex mandibular and maxillary reconstructions. The lateral border of the scapula provides up to 14 cm of thick, straight corticocancellous bone that can be osteotomized where desired. The thin blade of the scapula provides optimum tissues for palate and orbital floor reconstruction. There have been no flap failures and minimal donor-site complications.