Luther H. Holton

The use of acellular dermal matrix to prevent capsule formation around implants in a primate model.

Background: Implant-based breast reconstruction is a popular option after mastectomy, but capsular contracture may detract from long-term outcomes. The authors have observed that breast implants covered with acellular dermal matrix (AlloDerm) are less likely to develop a capsule in the area where the implant is in direct contact with the acellular matrix. The authors tested this observation experimentally by comparing capsular formation around implants in the presence and absence of AlloDerm in primates. Methods: Eight smooth-surfaced tissue expanders were implanted into eight African green monkeys. In four experimental animals, a sheet of AlloDerm was draped over the tissue expander so as to cover the implant. Four control animals underwent placement of a tissue expander only. Animals were killed after 10 weeks and specimens underwent histologic and immunohistochemical analysis. Results: Hematoxylin and eosin staining of control specimens revealed the presence of a distinct layer of wavy, parallel arrays of collagen fibers consistent with capsule formation. Immunostaining identified abundant myofibroblasts, a profibrotic cell found in breast capsules. In the AlloDerm-covered specimens, no capsule layer was visible, and specimens stained weakly for myofibroblasts. The difference in myofibroblast staining intensity was statistically significant. Conclusions: The use of AlloDerm to partially enclose implants effectively prevented formation of a capsule in areas where AlloDerm contacted the implant at 10 weeks. Long-term studies will be required to determine whether this is a durable result that can be reproduced in humans.

Incisional negative-pressure wound therapy versus conventional dressings following abdominal wall reconstruction: a comparative study.

BackgroundImprovements in surgical techniques have allowed us to achieve primary closure in a high percentage of large abdominal hernia repairs. However, postoperative wound complications remain common. The benefits of negative-pressure wound therapy (NPWT) in the management of open abdominal wounds are well described in the literature. Our study investigates the effects of incisional NPWT after primary closure of the abdominal wall. MethodsA retrospective chart review was performed for the period between September 2008 and May 2011 to analyze the outcomes of patients treated postoperatively with incisional NPWT versus conventional dry gauze dressings. Patient information collected included history of abdominal surgeries, smoking status, and body mass index. Postoperative complications were analyzed using &khgr;2 exact test and logistic regression analysis. ResultsFifty-six patients were included in this study; of them, 23 were treated with incisional NPWT, whereas 33 received conventional dressings. The rates of overall wound complications in groups I and II were 22% and 63.6%, respectively (P = 0.020). The rates of skin dehiscence were 9% and 39%, respectively (P = 0.014). Both outcomes achieved statistical significance. Rates of infection, skin and fat necrosis, seroma, and hernia recurrence were 4%, 9%, 0%, and 4% for group I and 6%, 18%, 12%, 9% for group II, respectively. ConclusionsThis study suggests that incisional NPWT following abdominal wall reconstruction significantly improves rates of wound complication and skin dehiscence when compared with conventional dressings. Prospective, randomized, controlled studies are needed to further characterize the potential benefits of this therapy on wound healing after abdominal wall reconstruction.

Acellular Dermal Matrix Compared with Synthetic Implant Material for Repair of Ventral Hernia in the Setting of Peri-Operative Staphylococcus aureus Implant Contamination: A Rabbit Model

BACKGROUND Implant infection is a common clinical complication of abdominal hernia repair. Our objectives were to determine if acellular dermal matrix (ADM) grafts resisted Staphylococcus aureus infection better (as measured by ability to reduce or clear bacterial counts) than synthetic (polytetrafluoroethylene [PTFE]) mesh when used in abdominal wall reconstruction, and to determine whether vascularization of the implant occurred. We hypothesized that the ability of the ADM grafts to vascularize and allow cellular ingrowth would allow the immune system to clear the infection better in these animals. METHODS In New Zealand White rabbits (average weight, 3.0 kg), a full-thickness 3 x 3 cm(2) abdominal defect was created, then repaired with an interpositional implant (ADM, n = 62; PTFE, n = 57). Before skin closure, the epidermal surface of each implant was inoculated with 1 mL of S. aureus at various concentrations (10(4) colony-forming units [CFU]/mL, n = 82; 10(6) CFU/mL, n = 27; 10(9) CFU/mL, n = 10), and the rabbits were harvested at either day 7 or day 21. RESULTS At day 7, ADM grafts inoculated with 10(4) CFU had lower counts or no bacteria (p = 0.006), fewer adhesions (p = 0.005), and fewer abscesses (p = 0.008) than PTFE grafts. By day 21, more ADM (n = 12) than PTFE (n = 0) grafts were free of bacteria (p = 0.002). Fewer rabbits with ADM grafts formed abscesses (13 vs. 19; p = 0.03). When evaluating the 7- and 21-day 10(4) CFU groups combined, a total of 15 rabbits with ADM cleared the bacteria completely vs. none of those with PTFE grafts (p < 0.001). There was no significant difference in bacterial counts or wound complications at days 7 or 21 between PTFE and ADM implants when inoculated with 10(6) CFU. All rabbits inoculated with 10(9) CFU died of sepsis within 48 h. Herniation did not occur in any of the animals. CONCLUSIONS Our study demonstrates that ADM resists surgical site infection caused by S. aureus in an animal model without compromising the ventral hernia repair. This ability of ADM grafts to perform well in the setting of infection is most likely attributable to their capacity to vascularize and aid clearance of bacteria.

Comparison of acellular dermal matrix and synthetic mesh for lateral chest wall reconstruction in a rabbit model.

Background: Synthetic mesh is used for chest wall reconstruction, but infection or exposure can occur and necessitate removal. Human acellular dermal matrix (AlloDerm) has been used to reconstruct musculofascial defects in the trunk with low infection and herniation rates. AlloDerm may have advantages over synthetic mesh for chest wall reconstruction. This study compared outcomes and repair strengths of AlloDerm to expanded polytetrafluoroethylene mesh used for repair of rib cage defects. Methods: A 3 × 3-cm, full-thickness, lateral rib cage defect was created in each rabbit and repaired with expanded polytetrafluoroethylene (n = 8) or acellular dermal matrix (n = 9). At 4 weeks, the animals were euthanized and evaluated for lung herniation/dehiscence, strength of adhesions between the implant and intrapleural structures, and breaking strength of the implant materials and the implant-fascia interface. Tissue sections were analyzed with histologic and immunohistochemical staining to evaluate cellular infiltration and vascularization. Results: No herniation or dehiscence occurred with either material. The incidence and strength of adhesions was similar between materials. The mean breaking strength of the AlloDerm-fascia interface (14.5 ± 8.9 N) was greater than the expanded polytetrafluoroethylene–fascia interface (8.7 ± 4.4 N; p = 0.027) and similar to the rib-intercostal-rib interface of the contralateral native chest wall (14.0 ± 5.6 N). The AlloDerm grafts became infiltrated with cells and vascularized after implantation. Conclusions: AlloDerm used for chest wall reconstruction results in greater implant-defect interface strength than expanded polytetrafluoroethylene. The ability of AlloDerm to become vascularized and remodeled by autologous cells and to resist infection may be advantageous for chest wall reconstruction.

A heterotopic primate model for facial composite tissue transplantation

The purpose of this study was to develop a nonhuman primate model for heterotopic composite tissue facial transplantation in which to study the natural history of facial transplantation and evaluate immunosuppressive regimens. A composite oromandibular facial segment transplant based on the common carotid artery was evaluated. Flaps from 7 cynomolgus monkeys were transplanted to the groins of 7 recipients at the superficial femoral artery and vein. The immunosuppressive regimen consisted of thymoglobulin, rapamycin, and tacrolimus. Allograft survival ranged from 6 to 129 days. Histology performed in the long-term survivor at the time of necropsy revealed extensive inflammation and necrosis of the allograft skin; however, muscle and bone elements were viable, with minimal inflammation. This heterotopic facial transplantation model avoids the potential morbidity of mandibular resection and orthotopic facial transplantation. Our work also concurs with the work of other groups who found that the skin component is the most antigenic.

Massive localized lymphedema revisited: A quickly rising complication of the obesity epidemic

AbstractMassive localized lymphedema (MLL) is a rising and potentially fatal complication of the obesity epidemic. Described as a benign lymphoproliferative overgrowth of obese patients, MLL is a form of secondary lymphedema, caused by the obstruction of lymphatic flow, with characteristic clinical and histological presentation. Patients have a large mass with classic skin changes often accompanied by lymphatic weeping that require complex reconstruction. Although oftentimes benign, if left untreated, MLL can progress to angiosarcoma, further supporting the need for more research into MLL and its sequelae. We present a unique case of MLL of the mons pubis in a 52-year-old man with a body mass index of 75.7 kg/m2. The literature was comprehensively reviewed with a total of 65 cases of MLL being described, 9 of which resulted in angiosarcoma (10.3% of all cases), 6 of which resulted in death (9.2% of all cases). We found a female predominance of 1.24 to 1, an average weight of 183 kg, and a 48.5% majority of cases in the thigh.

Prevention of microsurgical anastomotic thrombosis using aspirin, heparin, and the glycoprotein IIb/IIIa inhibitor tirofiban

Background: Recent clinical trials involving patients with acute coronary syndromes have demonstrated significant reduction in the progression of coronary artery thrombosis using a regimen of aspirin, heparin, and the glycoprotein IIb/IIIa inhibitor tirofiban. Acute coronary syndromes and free tissue transfer are similar pathophysiologically in that they both involve endothelial injury, thrombosis, and ischemia. In this study, the authors investigate tirofiban, combined with aspirin and heparin, for the prevention of microsurgical anastomotic thrombosis in a thrombogenic rat model. Methods: Using a randomized, controlled, double-blind experimental design, 80 thrombogenic anastomoses were performed on rat femoral arteries (n = 40) and veins (n = 40). Preoperatively, each rat received one of four treatment regimens: aspirin and heparin (regimen 1), aspirin and heparin plus tirofiban (regimen 2), tirofiban alone (regimen 3), or isotonic saline (control) (regimen 4). Vessels were assessed for patency at 5, 15, 30, and 120 minutes after reperfusion and then harvested for microscopic analysis. Results: At 120 minutes after reperfusion, regimen 1 had an arterial and venous patency rate of 80 percent and 70 percent, respectively, whereas the vessel patency rate for regimen 2 was 100 percent. The difference between regimens 1 and 2 was not statistically significant. Regimens 3 and 4 had vessel patency rates of 40 percent or less. The aspirin/heparin and aspirin/heparin/tirofiban groups both demonstrated significantly improved vessel patency and significantly less thrombotic occlusion compared with controls. Conclusions: Combination therapy with aspirin, heparin, and tirofiban significantly increases arterial and venous patency and decreases anastomotic thrombus formation in thrombogenic anastomoses in rats. The role of glycoprotein IIb/IIIa inhibitors in microsurgery warrants further investigation.

A novel reconstructive technique following central lumpectomy.

Breast conservation therapy is a wellestablished treatment method for subareolar breast cancers, provided that the nipple-areola complex is completely removed, adequate surgical margins are obtained following tumor resection, and adjuvant radiation therapy is received. After resection of the central breast and nipple-areola complex, the remaining surgical defect is commonly closed primarily. However, this frequently results in an unattractive deformity, especially with larger subareolar tumors. We describe an immediate reconstructive technique after central lumpectomy and nipple-areola complex resection that demonstrates excellent cosmesis following radiation therapy.

Improving long-term projection in nipple reconstruction using human acellular dermal matrix: An animal model

Reconstructed nipples rapidly lose projection. We describe the use of human acellular dermal matrix (ADM) to improve long-term projection of nipple flaps. Athymic rats were randomized to 3 groups; each received 2 nipples: bell flap (control, n = 16 nipples), bell flap with a cylinder of implanted ADM (n = 24), or bell flap with intraflap injection of micronized ADM (MADM) (n = 10). Seven of 24 ADM nipples extruded (30%). By 12 weeks, the control nipples maintained 44% of initial projection compared with 70% for ADM nipples (P = 0.000025). The MADM nipples maintained 49% of initial projection after 12 weeks (P = 0.55 compared with control). No MADM nipples extruded. ADM grafts maintain long-term projection better than local tissue flaps alone. We hypothesize that MADM may limit extrusion and allow for serial injection of nipples. Based on the promising results of this study, clinical trials are warranted using human ADM and/or human MADM for nipple reconstruction.

Significant predictors of complications after sternal wound reconstruction: a 21-year experience.

BackgroundWe sought to identify patient comorbidities that predict complications after tissue flap sternal reconstruction. MethodsA retrospective study, December 1989 to December 2010, analyzed numerous comorbidities, including diabetes mellitus (DM), hypertension (HTN), coronary artery disease, congestive heart failure (CHF), and renal insufficiency, as independent risk factors for postoperative complications. Pearson &khgr;2 test, Fisher exact test, 2-sample t test, and median-unbiased estimation were used for data analysis. Significance was P ⩽ 0.05. ResultsIn all, 106 patients received 161 sternal tissue flap repairs. Nineteen patients (18%) required reoperation because of complications, including recurrent wound infection, tissue necrosis, wound dehiscence, mediastinitis, and hematoma formation. Our analysis found DM, HTN, and CHF as significant predictors of complications after sternal reconstruction (P = 0.014, 0.012, and 0.006). ConclusionsResults suggest DM, HTN, and CHF may contribute to complications after tissue flap repair of sternal wounds, possibly through impaired perfusion and healing of repairs.