Free-flap coverage of the exposed Achilles tendon

Posterior skin loss of the distal lower leg enhances the risk of exposure of the Achilles tendon. Most commonly, these wounds are a sequela to peripheral vascular insufficiency or else posttraumatic in origin. As a consequence, local flaps or skin grafts frequently are inadequate options for achieving coverage. Free-tissue transfers have proven to be a reasonable alternative in these situations for preservation of tendon function or even limb salvage. In this series of 12 patients, small defects were best covered with fasciocutaneous flaps, whereas the larger and usually chronic, concomitantly suppurating wounds required muscle flaps. Eighty-three percent (10 of 12) of patients remained ambulatory with healed wounds, obviating the need for extremity amputation.     

Vascular endothelial growth factor expression in pig latissimus dorsi myocutaneous flaps after ischemia reperfusion injury

Exogenous administration of vascular endothelial growth factor (VEGF) improves long-term viability of myocutaneous flaps. However, endogenous expression of this substance in flaps following ischemia-reperfusion injury has not been reported previously. Endogenous production of VEGF was measured in myocutaneous pig latissimus dorsi flaps after ischemia-reperfusion injury. Latissimus dorsi myocutaneous flaps (15 x 10 cm) were simultaneously elevated bilaterally in six Yorkshire-type male pigs (25 kg). Before elevation, three flap zones (5 x 10 cm) were marked according to their distance from the vascular pedicle. After isolation of the vascular pedicle, ischemia-reperfusion injury was induced in one flap by occlusion of the thoracodorsal artery and vein for 4 hours, followed by 2 hours of reperfusion. The contralateral flap served as a control. Perfusion in each zone was monitored by laser Doppler flowmetry at baseline, during ischemia, and during reperfusion. At the end of the protocol, skin and muscle biopsies of each flap zone and adjacent tissues were obtained for later determination of VEGF protein levels. VEGF concentrations were quantified using the Quantikine human VEGF immunoassay. Skin perfusion was similar among all flap zones before surgery. Flow fell in all flaps immediately after flap elevation. After 4 hours of ischemia, blood flow in the ischemic flaps was significantly decreased (p < 0.05) compared with nonischemic control flaps. After 2 hours of reperfusion, flow in ischemic flap skin recovered to levels similar to those in control flaps. VEGF protein concentrations in muscle tissue exceeded concentrations in skin and decreased from zones 2 to 3 in control and ischemic flaps. No significant differences in VEGF concentrations between ischemic and control muscle zones were observed. However, the concentration of VEGF in all muscle zones was significantly higher (p < 0.05) than muscle adjacent to the flap. Concentrations in skin zones 1 and 2 were significantly higher (p < 0.05) in ischemic flaps than in control flaps, but levels in zone 3 (most ischemic flaps) showed no significant difference.     

The role of intrinsic muscle flaps of the foot for bone coverage in foot and ankle defects in diabetic and nondiabetic patients

Local muscle flaps, pioneered by Ger in the late 1960s, were extensively used for foot and ankle reconstruction until the late 1970s when, with the evolution of microsurgery, microsurgical free flaps became the reconstructive method of choice. To assess whether the current underuse of local muscle flaps in foot and ankle surgery is justified, the authors identified from the Georgetown Limb Salvage Registry all patients who underwent foot and ankle reconstruction with local muscle flaps and microsurgical free flaps from 1990 through 1998. By protocol, flap coverage was the reconstructive choice for defects with exposed tendons, joints, or bone. Local muscle flaps were selected over free flaps if the defect was small (3 x 6 cm or less) and within reach of the local muscle flap. During the same time frame, the authors performed 45 free flaps (96 percent success rate) in the same areas when the defects were too large or out of reach of local muscle flaps. Thirty-two consecutive patients underwent local muscle flap reconstruction for 19 diabetic wounds and 13 traumatic wounds. All wounds, after debridement, had exposed bone at their base, with osteomyelitis being present in 52 percent of the diabetic wounds and in 70 percent of the nondiabetic wounds. Wounds were located in the hindfoot (47 percent), midfoot (44 percent), and ankle (9 percent). Vascular disease was more prevalent in the diabetic group, in which 42 percent of the affected limbs required revascularization procedures before reconstruction (versus 7 percent in the nondiabetic group). Subsequently, 83 total operations were required to heal the wounds, of which 46 percent were limited to debridement only. Thirty-four pedicled muscle flaps were used: 19 abductor digiti minimi (56 percent), nine abductor hallucis (26 percent), three extensor digitorum brevis (9 percent), two flexor digitorum brevis (6 percent), and one flexor digiti minimi (3 percent). An additional skin graft for complete coverage was required in 18 patients (53 percent). One patient died and one flap developed distal necrosis, for a 96 percent success rate. The complication rate was 26 percent and included patient death, dehiscence, and partial flap or split-thickness skin graft loss. Twenty-nine of the 32 wounds healed. One patient died in the postoperative period; in two others the wounds failed to heal and required below-knee amputations, for an overall limb salvage rate of 91 percent. Diabetes did not significantly affect healing and limb salvage rates. Diabetes, however, did affect healing times (twofold increase), length of stay (2.7 times as long), and long-term survival (63 percent survival in diabetic patients versus 100 percent in the trauma group). Local muscle flaps provide a simpler, less expensive, and successful alternative to microsurgical free flaps for foot and ankle defects that have exposed bone (with or without osteomyelitis), tendon, or joint at their base. Diabetes does not appear to adversely affect the effectiveness of these flaps. Local muscle flaps should remain on the forefront of possible reconstructive options when treating small foot and ankle wounds that have exposed bone, tendon, or joint.     

The muscle flap in the treatment of chronic lower extremity osteomyelitis: results in patients over 5 years after treatment.

Preliminary reports have indicated that debridement of the bony sequestrum followed by muscle-flap coverage allows successful treatment of chronic osteomyelitis. To determine the long-term effectiveness of this procedure, 34 consecutive patients with chronic osteomyelitis of the distal lower extremity treated with debridement, a 10- to 14-day course of culture-specific antibiotics, and immediate muscle-flap coverage were evaluated. Patients were treated from 1979 through 1984, and long-term (greater than 5 years) follow-up was available for 27 (79 percent). Twenty-three (85 percent) of these patients underwent microvascular muscle transplantation (gracilis or latissimus dorsi), and four underwent local muscle flaps (gastrocnemius or soleus) for immediate wound coverage. Twenty-four patients (89 percent) healed and were without recurrence over long-term (greater than 5 years, mean 7.4 years) follow-up. Of the three with recurrence, two were cured (greater than 5 years follow-up) after additional muscle-flap procedures. Thus the overall success rate was 96 percent, with a minimum 5-year follow-up. Guidelines for muscle-flap selection and treatment techniques in current use are presented. Debridement and immediate muscle-flap coverage provide effective, single-stage treatment of chronic osteomyelitic wounds and allow antibiotics to be restricted to short-term use. Furthermore, muscle flaps covered with skin grafts provide durable coverage while allowing subsequent ancillary procedures (i.e., bone grafts) to be performed under the flaps.     

Bipedicle paraspinous muscle flaps for spinal wound closure: an anatomic and clinical study

The purpose of this study was to evaluate the vascular anatomy of the paraspinous muscles and review their clinical use as bipedicled flaps in spinal wound closure. Anatomically, through cadaver dissections, lead oxide injections, and radiographic imaging, the blood supply to the paraspinous muscles was determined. Clinically, 29 consecutive patients treated with spinal wounds and exposed bone or hardware were reviewed retrospectively. Of these patients, 19 underwent closure in delayed primary fashion, whereas 10 were referred to plastic surgery for reconstruction because of the complex nature of their wounds. The cadaver study demonstrated the paraspinous muscles to possess a segmental arterial supply through medial and lateral perforators. Division of the medial perforators allowed for medial advancement of the muscles. Lead oxide injection of the lateral perforators demonstrated adequate medial muscle perfusion with ligation of the medial perforators. Ten of the 29 patients (six women, four men, 32 to 62 years of age) were reconstructed with paraspinous (eight), latissimus (one), and trapezius (one) muscle flaps. A higher complication rate was found in wounds closed in delayed primary fashion (13 of 19 patients, 68 percent) than those reconstructed with muscle flaps (2 of 10 patients, 20 percent) (p = 0.021). Follow-up of the muscle flap reconstructed patients averaged 12 months (range, 3 to 27 months). Cadaver muscle injections predicted and clinical cases confirmed that the paraspinous muscles can be raised on lateral perforators and advanced medially to close lumbar spine wounds reliably with fewer complications.     

Prophylaxis of local vascular graft infection with levofloxacin incorporated into albumin-sealed dacron graft (LVFX-ALB Graft).

An animal model was used to assess the efficacy of levofloxacin (LVFX) incorporated into albumin (ALB)-sealed Dacron (LVFX-ALB) graft for the prevention of vascular graft infections caused by Staphylococcus aureus. Under general anesthetic, an interposition graft was placed into dog carotid artery. On completion of the operation, 0.1 ml of normal saline containing 10(7) colony-forming units (CFU) of a slime-producing S. aureus was inoculated directly onto the graft. After 1 day, the samples were sterilely harvested. The antibacterial activity of LVFX into the LVFX-ALB graft was evaluated by colony counting in bacterial cultures and by the fluorescent antibody method staining bacteria adhesion to the grafts. LVFX-ALB grafts had a lower infection rate than the control grafts (1/4, 10(2) CFU vs 4/4, 1.50 x 10(5)+/-1.38 x 10(5)CFU (mean+/-SE)). In an immunostaining study, LVFX-ALB grafts had small fluorescent areas showing S. aureus adhesion, while fluorescence was observed over the entire surface of the control grafts. Therefore, LVFX-ALB presumably had a bactericidal action and adhesive prevention against inoculated S. aureus. LVFX-ALB may be useful in preventing graft infections during and immediately after vascular reconstruction.     

Treatment of chronic infected hip arthroplasty wounds by radical debridement and obliteration with pedicled and free muscle flaps

Nine patients with extensive wounds of the hip joint due to chronic infection following total hip arthroplasty or internal fixation of fractures of the femoral head and neck have been treated by serial radical debridements to remove infected bone, contaminated remnants of bone cement, and the surrounding fibrotic soft tissues. The resultant deep cavity extending down to the acetabulum has then been obliterated with either pedicled muscle flaps or free muscle flaps. Subcutaneous or transpelvic transposition of rectus abdominis muscle flaps is preferred for smaller defects, but only the free latissimus dorsi muscle flap provides sufficient volume of tissue to obliterate the more extensive hip defects. Systemic antibiotics have been continued only for a short-term course of 14 days postoperatively. There has been no recurrence of infection, with follow-up ranging between 6 months and 3 1/4 years. One patient has undergone reimplantation of a second custom hip prosthesis into the vascularized bed of a free latissimus dorsi muscle flap.     

Salvage of chronically exposed Gore-Tex vascular access grafts in the hemodialysis patient

Exposure and infection of a Gore-Tex vascular access graft often results in removal of the graft. Salvage of the graft is possible, however, with the use of well-vascularized muscle flaps. In 1982, Hodgkinson was the first to use a sublimis muscle flap to cover an exposed vascular access graft. We used the flexor carpi ulnaris and flexor digitorum superficialis to cover exposed Gore-Tex grafts in nine patients. The sublimis was used to cover distal graft exposures, and the longer flexor carpi ulnaris muscle was used to cover more proximal sites. Multiple exposures required both flaps or combinations of muscle flaps and local rotation flaps. Eight of nine chronically exposed grafts were salvaged using these techniques; a graft was removed from one patient because of diffuse unrecognized graft bed infection. Disability is minimized by using only part of the sublimis, and loss of the flexor carpi ulnaris is compensated by local muscles with similar actions. Vascular puncture can be continued during healing.     

Peripheral neovascularization of muscle and musculocutaneous flaps in the pig.

Late loss of free muscle flaps following surgical or accidental trauma to the dominant vascular pedicle has been reported. In this study, time-dependent ligation of the dominant vascular pedicle was undertaken in denervated latissimus dorsi musculocutaneous or muscle-only island flaps in the pig. Muscle flaps were covered with a skin graft, and silicon rubber sheets were inserted between the flaps and their bases to simulate a poorly vascularized bed. Hemodynamic and viability studies were then performed using intravenous fluorescein (skin viability), tetrazolium blue (muscle viability), and radiolabeled 15-micron microspheres (capillary blood flow). Blood flow did not change in acutely raised musculocutaneous flaps (n = 10) but was significantly elevated in acutely raised muscle-only flaps (n = 10), suggesting that the skin paddle may steal blood flow from the underlying muscle in musculocutaneous flaps. Peripheral neovascularization at 1 day to 8 weeks was assessed (n = 30). Viability increased during the first week of revascularization and was not different in musculocutaneous and muscle-only flaps. Revascularization of muscle-only flaps was enhanced compared with musculocutaneous flaps in the 2- to 8-week period.     

A 10-year experience in nasal reconstruction with the three-stage forehead flap

Because of its ideal color and texture, forehead skin is acknowledged as the best donor site with which to resurface the nose. However, all forehead flaps, regardless of their vascular pedicles, are thicker than normal nasal skin. Stiff and flat, they do not easily mold from a two-dimensional to a three-dimensional shape. Traditionally, the forehead is transferred in two stages. At the first stage, frontalis muscle and subcutaneous tissue are excised distally and the partially thinned flap is inset into the recipient site. At a second stage, 3 weeks later, the pedicle is divided. However, such soft-tissue "thinning" is limited, incomplete, and piecemeal. Flap necrosis and contour irregularities are especially common in smokers and in major nasal reconstructions. To overcome these problems, the technique of forehead flap transfer was modified. An extra operation was added between transfer and division.At the first stage, a full-thickness forehead flap is elevated with all its layers and is transposed without thinning except for the columellar inset. Primary cartilage grafts are placed if vascularized intranasal lining is present or restored. Importantly, at the first stage, skin grafts or a folded forehead flap can be used effectively for lining. A full-thickness skin graft will reliably survive when placed on a highly vascular bed. A full-thickness forehead flap can be folded to replace missing cover skin, with a distal extension, in continuity, to supply lining. At the second stage, 3 weeks later during an intermediate operation, the full-thickness forehead flap, now healed to its recipient bed, is physiologically delayed. Forehead skin with 3 to 4 mm of subcutaneous fat (nasal skin thickness) is elevated in the unscarred subcutaneous plane over the entire nasal inset, except for the columella. Skin grafts or folded flaps integrate into adjacent normal lining and can be completely separated from the overlying cover from which they were initially vascularized. If used, a folded forehead flap is incised free along the rim, completely separating the proximal cover flap from the distal lining extension. The underlying subcutaneous tissue, frontalis muscle, and any previously positioned cartilage grafts are now widely exposed, and excess soft tissue can be excised to carve an ideal subunit, rigid subsurface architecture. Previous primary cartilage grafts can be repositioned, sculpted, or augmented, if required. Delayed primary cartilage grafts can be placed to support lining created from a skin graft or a folded flap. The forehead cover skin (thin, supple, and conforming) is then replaced on the underlying rigid, recontoured, three-dimensional recipient bed. The pedicle is not transected. At a third stage, 3 weeks later (6 weeks after the initial transfer), the pedicle is divided.Over 10 years in 90 nasal reconstructions for partial and full-thickness defects, the three-stage forehead flap technique with an intermediate operation was used with primary and delayed primary grafts, and with intranasal lining flaps (n = 15), skin grafts (n = 11), folded forehead flaps (n = 3), turnover flaps (n = 5), prefabricated flaps (n = 4), and free flaps for lining (n = 2). Necrosis of the forehead flap did not occur. Late revisions were not required or were minor in partial defects. In full-thickness defects, a major revision and more than two minor revisions were performed in less than 5 percent of patients. Overall, the aesthetic results approached normal.The planned three-stage forehead flap technique of nasal repair with an intermediate operation (1) transfers subtle, conforming forehead skin of ideal thinness for cover, with little risk of necrosis; (2) uses primary and delayed primary grafts and permits modification of initial cartilage grafts to correct failures of design, malposition, or scar contraction before flap division; (3) creates an ideal, rigid subsurface framework of hard and soft tissue that is reflected through overlying skin and blends well into adjacent recipient tissues; (4) expands the application of lining techniques to include the use of skin grafts for lining at the first stage, or as a "salvage procedure" during the second stage, and also permits the aesthetic use of folded forehead flaps for lining; (5) ensures maximal blood supply and vascular safety to all nasal layers; (6) provides the surgeon with options to salvage reconstructive catastrophes; (7) improves the aesthetic result while decreasing the number and difficulty of revision operations and overall time for repair; and (8) emphasizes the interdependence of anatomy (cover, lining, and support) and provides insight into the nature of wound injury and repair in nasal reconstruction.     

The use of anterolateral thigh perforator flaps in chronic osteomyelitis of the lower extremity

From April of 2000 to May of 2003, 28 consecutive patients with chronic osteomyelitis of the lower extremity underwent surgical debridement and reconstruction with anterolateral thigh perforator flaps (six cases were combined with vastus lateralis muscle flaps). All wounds were open for a minimum period of 6 weeks (average, 24.7 months; range, 6 weeks to 52 months). The average patient age was 42.8 years (range, 18 to 71 years), there were 21 male and seven female patients, and the average follow-up period was 18.2 months (range, 5 to 41 months). The cause of injury was an open fracture in 10 cases, secondary wound complications after reduction in eight cases, and diabetic foot in 10 cases. The surface defects ranged from 50 to 153 cm. The wounds were debrided an average of 2.5 times and then reconstructed with flap and treated with antibiotics for 6 weeks. Antibiotic beads were used in six cases and secondary bone graft procedures were performed in seven cases 3 months after the flap coverage. All 28 flaps were successful without any signs of recurrences or persistent osteomyelitis, but partial wound dehiscence was observed during early rehabilitation in two cases suspected of delayed healing caused by diabetes. These wounds healed spontaneously. All patients achieved acceptable gait function after rehabilitation. No debulking procedure was necessary in any case. Although the muscle flap is known to provide superior vascular supply, the type of flap used for coverage seems to be less critical in the final outcome, provided that total debridement and obliteration of dead spaces are achieved. A well-vascularized anterolateral thigh perforator flap was successfully used to combat infection and bring stability to wounds with chronic osteomyelitis.     

Differing flow patterns between ischemically challenged flap skin and flap skeletal muscle: implications for salvage regimens.

In this study, the authors tested the hypothesis that there is a significant difference in spatial patterns of reflow in skin as opposed to skeletal muscle after an ischemic insult. The authors believe that this pathophysiologic difference between the two flap types has significant implications for flap salvage strategies. Bilateral buttock skin flaps (10 x 18 cm) and latissimus dorsi myocutaneous flaps (10 x 20 cm) were elevated in Landrace pigs (n = 7). Flaps on one side of the animal were randomly assigned to 6 hours of arterial occlusion, with the contralateral side acting as control. At 15 minutes, 1 hour, and 4 hours after reflow, radioactive microspheres (15 microm) were injected into the left ventricle. After 18 hours of reperfusion, skin and muscle viability were estimated by intravenous fluorescein and soaking in nitroblue tetrazolium, respectively. Flow rates in the skin with an ischemia-reperfusion injury were significantly reduced (30 to 53 percent), at all time intervals, compared with controls. The flow rate in the fluorescent skin with ischemia-reperfusion injury of the latissimus dorsi flaps (0.037 ml/min/g at 15 min) was greater than in that of the buttock flaps (0.018 ml/min/g). The muscle flaps with ischemia-reperfusion injury had significantly higher flow rates than control muscle flaps at all time intervals studied (at 1 hour, 0.32 ml/min/g compared with 0.16 ml/min/g, respectively). In flap skeletal muscle, an early hyperemic phase during reperfusion maintains a significant blood flow to all regions, including the area of the flap that is destined for necrosis. In flap skin, however, there is a marked decrease in flow rates. These differences have important implications for the intravascular delivery of therapeutic agents to the damaged portions of the flap. Transdermal drug delivery systems should be explored as an alternative to intravascular regimens for the salvage of flap skin with ischemia-reperfusion injury.     

A reliable approach to the closure of large acquired midline defects of the back

A systematic regionalized approach for the reconstruction of acquired thoracic and lumbar midline defects of the back is described. Twenty-three patients with wounds resulting from pressure necrosis, radiation injury, and postoperative wound infection and dehiscence were successfully reconstructed. The latissimus dorsi, trapezius, gluteus maximus, and paraspinous muscles are utilized individually or in combination as advancement, rotation, island, unipedicle, turnover, or bipedicle flaps. All flaps are designed so that their vascular pedicles are out of the field of injury. After thorough debridement, large, deep wounds are closed with two layers of muscle, while smaller, more superficial wounds are reconstructed with one layer. The trapezius muscle is utilized in the high thoracic area for the deep wound layer, while the paraspinous muscle is used for this layer in the thoracic and lumbar regions. Superficial layer and small wounds in the high thoracic area are reconstructed with either latissimus dorsi or trapezius muscle. Corresponding wounds in the thoracic and lumbar areas are closed with latissimus dorsi muscle alone or in combination with gluteus maximus muscle. The rationale for systematic regionalized reconstruction of acquired midline back wounds is described.     

Surgical augmentation of skin blood flow and viability in a pig musculocutaneous flap model

A porcine rectus abdominis musculocutaneous (TRAM) flap model was designed and validated in nine pigs. This TRAM flap was based on the deep inferior epigastric (DIE) vessels with an 8 x 18 cm transverse skin paddle at the superior end of the rectus abdominis muscle. The model was subsequently used to test our hypothesis of surgical augmentation of flap viability by vascular territory expansion. Specifically, we observed that ligation of the superior epigastric (SE) vessels at 4, 7, 14, and 28 days (N = 6 to 8) prior to raising the TRAM flaps significantly increased (p less than 0.05) the length and area of the viable skin in the transverse skin paddles of the treatment flaps compared with the contralateral shammanipulated control flaps. This significant increase in skin viability was seen to be accompanied by a significant increase (p less than 0.05) in skin and muscle capillary blood flow in the treatment TRAM flaps compared with the controls (N = 9). The mechanism of vascular territory expansion is unclear. We postulate that hypoxia resulting from the ligation of the superior epigastric vessels prior to the flap surgery may play a role in the triggering of the deep inferior epigastric artery to take over some of the territory previously perfused by the superior epigastric artery. This would then increase the skin and muscle capillary blood flow in the transverse paddle when the TRAM flap was raised on the deep inferior epigastric vascular pedicle.     

Factors affecting outcome in free-tissue transfer in the elderly

Free-tissue transfers have become the preferred surgical technique to treat complex reconstructive defects. Because these procedures typically require longer operative times and recovery periods, the applicability of free-flap reconstruction in the elderly continues to require ongoing review. The authors performed a retrospective analysis of 100 patients aged 65 years and older who underwent free-tissue transfers to determine preoperative and intraoperative predictors of surgical complications, medical complications, and reconstructive failures. The parameters studied included patient demographics, past medical history, American Society of Anesthesiology (ASA) status, site and cause of the defect, the free tissue transferred, operative time, and postoperative complications, including free-flap success or failure. The mean age of the patients was 72 years. A total of 46 patients underwent free-tissue transfer after head and neck ablation, 27 underwent lower extremity reconstruction in the setting of peripheral vascular disease, 10 had lower extremity traumatic wounds, nine had breast reconstructions, four had infected wounds, two had chronic wounds, and two underwent transfer for lower extremity tumor ablation. Two patients had an ASA status of 1, 49 patients had a status of 2, 45 patients had a status of 3, and four had a status of 4. A total of 104 flaps were transferred in these 100 patients. There were 49 radial forearm flaps, 34 rectus abdominis flaps, seven latissimus dorsi flaps, seven fibular osteocutaneous flaps, three omental flaps, three jejunal flaps, and one lateral arm flap. Four patients had planned double free flaps for their reconstruction. Mean operative time was 7.8 hours (range, 3.5 to 16.5 hours). The overall flap success rate was 97 percent, and the overall reconstructive success rate was 92 percent. There were six additional reconstructive failures related to flap loss, all of which occurred more than 1 month after surgery. Patients with a higher ASA designation experienced more medical complications (p = 0.03) but not surgical complications. Increased operative time resulted in more surgical complications (p = 0.019). All eight cases of reconstructive failure occurred in patients undergoing limb salvage surgery in the setting of peripheral vascular disease. Free-tissue transfer in the elderly population demonstrates similar success rates to those of the general population. Age alone should not be considered a contraindication or an independent risk factor for free-tissue transfer. ASA status and length of operative time are significant predictors of postoperative medical and surgical morbidity. The higher rate of reconstructive failure in the elderly peripheral vascular disease population compares favorably with other treatment modalities for this disease process.     

Reversing the detrimental effect of adriamycin on skin grafts in rats

We evaluated in a rat model the effects of a homologous fibrin glue in reversing the effects of Adriamycin on adherence and take of skin grafts. A total of 40 male Fisher rats were used in the study. During the first phase of the experiment, the animals were assigned to either group I (N = 10) receiving normal saline or group II (N = 10) receiving 6 mg/kg Adriamycin by tail vein injection 24 hours before surgery. Skin grafts with and without fibrin glue were placed over wounds in the backs of the animals and adherence was measured at 24 and 48 hours. In the second phase (N = 20), the experiment was repeated, this time evaluating the total area of skin graft take at 7 days. Fibrin glue was found to increase adherence and take of skin grafts in all Adriamycin-treated animals.     

Evidence for endothelium-dependent and endothelium-independent vasodilation in human skin flaps.

Acetylcholine (ACh) and nitroglycerin (NTG) were used as probes to study endothelium-dependent and endothelium-independent vascular relaxation in isolated perfused transverse paraumbilical human skin flaps. It was observed that ACh (10(-6) M) significantly (p < 0.05) decreased the vascular resistance and increased dermal capillary perfusion (assessed by surface fluorometry) in norepinephrine (NE, 10(-6) M) preconstricted skin flaps, despite the presence of a cyclooxygenase inhibitor (indomethacin, 3 x 10(-5) M) and a beta-adrenergic receptor antagonist (propranolol, 10(-6) M). The ability of ACh to induce vascular relaxation in NE-preconstricted skin flaps was lost after damaging the vascular endothelial lining with saponin perfusion (100 mg.L-1, 5 min). In contrast, NTG (10(-6) M) induced vascular relaxation to a similar extent before and after saponin treatment. In a separate study, ACh was seen to induce vascular relaxation in a concentration-dependent manner in skin flaps preconstricted with NE (10(-6) M). This vascular relaxation effect of ACh over the dose range of 10(-9)-10(-5) M was significantly (p < 0.01) inhibited in the presence of N omega-nitro-L-arginine (10(-5) M), a nitric oxide (NO) synthesis inhibitor. These observations were taken to indicate the presence of endothelium-dependent and endothelium-independent vascular relaxation in human skin flaps and that the ACh-induced endothelium-dependent relaxation is probably mediated by NO. The importance of impairment of endothelium-dependent relaxation in the pathogenesis of skin flap ischemia, and the potential use of topical nitrovasodilators or NO donors for prevention and (or) treatment of skin flap ischemia were also discussed.     

The effect of low-energy laser on skin-flap survival in the rat and porcine animal models.

Low-energy lasers are currently being used in the therapy of rheumatoid arthritis, chronic pain, muscle strain, and the promotion of wound healing in human and veterinary medicine. This study examined the effects of low-energy laser on skin-flap survival in a controlled interspecies study using the rat and porcine models. Twenty dorsal skin flaps based caudally were performed in 20 rats (10 laser-treated and 10 control flaps). The wounds were closed, and the flaps were sutured over the skin. Forty dorsal pig skin flaps based medially were raised in five pigs. The flaps were treated once per day for 10 days: 4 days preoperatively, the day of surgery, and 5 days postoperatively (30 s/cm3 per day). The average surviving rat flap surface area for the laser-treated flaps was 653 +/- 112 mm (mean +/- SD) and 580 +/- 60 mm in the control flaps, which was not significant (p greater than 0.05). In the porcine model, the average surviving area for the 20 laser-treated flaps was 949 +/- 174 mm, and the control average (n = 20) was 969 +/- 147 mm, also not significant. No beneficial effect was seen with low-energy laser preoperative and postoperative treatment of skin flaps in the rat and porcine models.     

The role of serum imbibition for skin grafts

Numerous studies of grafted skin suggest that full-thickness skin grafts are nourished by exudate from the recipient bed called a serum imbibition. However, whether serum imbibition by itself is sufficient for nourishment of skin grafts has not been shown definitely and directly. To clarify the role of serum imbibition, we performed a comparative study between 20 skin grafts and 20 musculocutaneous flaps. The nourishment of the cell in the skin graft is by serum imbibition. That in musculocutaneous flaps is mainly derived from blood supply. We evaluated the nourishment by means of the unique characteristics of the cell cycle. Once cells are put into a synthetic phase, they cannot reverse or stop the progress of the cell cycle. To take advantage of this characteristic of the cell cycle, prewounding methods (40 flaps were lifted once and put back to the original sites prior to the evaluation) were intended for the cells in pre-elevated skin to turn into a proliferating phase. Cells were examined by antibody against proliferating cell nuclear antigen immunohistologically, to determine whether they had turned into the proliferating phase or not. After 3 days, all flaps were reelevated; half (20 flaps) had their muscle layer and the neurovascular bundle removed to make a full-thickness skin graft. The rest (20 flaps) were only lifted. They were sutured back to the original sites. Ten skin grafts and musculocutaneous flaps each were harvested at 3 hours (1st day) and at 11 days (11th day) after the second operation. Bromodeoxyuridine, which is a thymidine analog and is taken into the cells in the synthetic phase, was introduced intraperitoneally 2 hours before the harvest. All flaps and grafts were evaluated histologically and immunohistologically. Proliferating cell nuclear antigen analysis showed that the prewounding method induced the cells of skin grafts and musculocutaneous flaps to proliferate before the implantation. Regarding the bromodeoxyuridine uptake, no significant differences could be seen between skin grafts and musculocutaneous flaps irrespective of their different nourishment. No structural changes, such as degenerative or necrotic, could be seen at the hair follicle and other glands even at the 11th day. Almost all of the layers of skin grafts survived as long as they were checked by light microscopy (hematoxylin and eosin stain). No differences could be seen between musculocutaneous flaps and skin grafts or between the 1st and 11th days in this study. We concluded that serum imbibition is sufficient for nourishment of skin grafts, just as blood supply is sufficient for nourishment of musculocutaneous flaps.     

Early regeneration of whole skeletal muscle grafts is unaffected by overexpression of IGF-1 in MLC/mIGF-1 transgenic mice.

Early myogenic events in regenerating whole muscle grafts were compared between transgenic MLC/mIGF-1 mice with skeletal muscle-specific overexpression of the Exon-1 Ea isoform of insulin-like growth factor-1 (mIGF-1) and control FVB mice, from day 3 to day 21 after transplantation. Immunocytochemistry with antibodies against desmin showed that skeletal muscle-specific overexpression of IGF-1 did not affect the pattern of myoblast activation or proliferation or the onset and number of myotubes formed in regenerating whole muscle grafts. Hypertrophied myotubes were observed in MLC/mIGF grafts at day 7 after transplantation, although such hypertrophy was transient, and the transgenic and control grafts had a similar appearance at later time points (days 10, 14, and 21). Immunostaining with antibodies to platelet endothelial cell adhesion molecule-1, which identifies endothelial cells, demonstrated no difference in the formation of new vascular network in grafts of transgenic and control mice. Skeletal muscle-specific overexpression of mIGF-1 does not appear to stimulate the early events associated with myogenesis during regeneration of whole muscle grafts.