Edward N Li

University of Maryland, Baltimore, Baltimore, Maryland, United States

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Publications (7)13.02 Total impact

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    ABSTRACT: 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. 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. 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. 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.
    No preview · Article · Sep 2008 · Surgical Infections
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    ABSTRACT: Abdominal wall dehiscence in renal transplantation patients risks the survival of the transplanted organ. No clear treatment algorithm exists in the literature for this group of patients. Between 1992 and 2001, the Division of Plastic Surgery at the University of Maryland treated 41 of 2499 renal transplant patients. Based on a retrospective review of these patients, an algorithm was developed to guide the management of midline and lower quadrant abdominal wall defects. Most lower quadrant defects were repaired with tensor fascia lata grafts. Most midline defects were repaired with the component separation technique. Use of a single- or multi-staged repair was based on the extent of infection. Hernia recurrence was 22% over 21 months. 80% of the transplant kidneys were functioning following repair. An algorithm for the repair of abdominal wall defects after kidney transplantation is presented taking into account the location and the extent of infection.
    No preview · Article · Nov 2005 · Hernia
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    ABSTRACT: This study was designed to assess the long-term efficacy of allogenic acellular dermal matrix (ADM) used as an interpositional graft for ventral hernia repair in a swine model. We created 12x4-cm full-thickness abdominal wall defects in 22 Yucatan miniature pigs. The defect was repaired with either two 6x4-cm pieces of AlloDerm (acellular dermal matrix processed from pig skin in order to avoid a xenogenic response, LifeCell Corporation, Branchburg, NJ USA) (n = 12), or expanded polytetrafluoroethylene mesh (ePTFE) (Gore-Tex, W.L. Gore & Associates, Inc., Newark, DE USA) (n = 10). In six pigs, a separate 3-cm fascial incision was made, which was then suture repaired as a control for tensiometry testing. The surgical sites were evaluated at either 3 months or 9 months for the presence of a hernia, stretching of the implant, adhesions, vascularity, and biomechanical strength. Two hernias occurred in both the ADM and the ePTFE groups. There was minimal stretching of the implants and minimal adhesions in both groups. Fluorescein testing and histology indicated vascular ingrowth into the ADM. There was no statistical difference between the mean breaking strengths of the ADM-fascial interface (106.5 N +/- SD 40.1), the interface between two pieces of ADM (149.1 N +/- SD 76.7), and the primary fascial repair (108.1 N +/- SD 20.9) at 9 months. The ADM-fascial interface had a significantly higher breaking strength than that of the ePTFE-fascia interface (66.1 N +/- SD 30.1) (P = 0.017, t-test, P = 0.043 Wilcoxon rank sum test). In this study, we were unable to demonstrate a difference between ADM and ePTFE in their ability to repair ventral hernias at 9 months in a swine model. The ADM additionally supports vascular ingrowth and exhibits increased breaking strength at the fascia-implant interface.
    No preview · Article · Dec 2004 · Hernia
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    ABSTRACT: Poststernotomy mediastinitis is an infrequent but highly dangerous complication following median sternotomy. Typically, such wounds are debrided aggressively of necrotic and foreign materials with subsequent flap reconstruction. Between December 1989 and January 2002, 69 patients were referred to the University of Maryland division of plastic surgery for mediastinal wound coverage. A total of 105 flaps of various types were used. Fifty-eight percent of the patients received a single flap. Ninety percent of the flaps used were pectoralis major flaps, whereas only 10% of the flaps were rectus abdominis, latissimus dorsi, or omentum flaps. Ten patients (14.5%) required reoperation. The most common comorbidity was diabetes mellitus. Those patients with diabetes mellitus were 9.1 times more likely to require reoperation after their sternal reconstruction compared with nondiabetic patients (95% confidence interval, 2.1-40.4). Four patients (5.8%) died less than 30 days from their flap procedure. The flap of first choice used in this series is the pectoralis major turnover flap, which is harvested in its entirety and split in the direction of its muscle fibers. Taking the entire muscle allows better coverage of the lower portion of the incision, resulting in far less frequent need for abdominal flaps and their associated morbidity.
    No preview · Article · Nov 2004 · Annals of Plastic Surgery
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    ABSTRACT: Auricular composite grafts are a useful reconstructive option, particularly for nasal reconstruction. This study evaluates the effect of hyperbaric oxygen (HBO) therapy on auricular composite graft survival in rabbits. Circular chondrocutaneous composite grafts of 0.5, 1, or 2 cm in diameter were resected from the ears of rabbits. The grafts were sutured back into position. Half the rabbits in each group received HBO postoperatively, consisting of 90 minutes at 2.4 atm. Rabbits received 7 treatments in 5 days. Control rabbits did not receive HBO. On day 21 the percentage area of graft survival was calculated from gross and histologic examination. Two-centimeter grafts treated with HBO (n = 8) had a mean graft survival rate of 85.8 +/- 15.7% compared with a survival rate of 51.31 +/- 38.5% for the control group (n = 8; P = 0.0478). There was no such benefit in smaller grafts. HBO could prove clinically useful for larger composite grafts.
    No preview · Article · Sep 2004 · Annals of Plastic Surgery
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    ABSTRACT: Involvement of the nipple-areolar complex is an infrequent area of distribution of hidradenitis suppurativa. The difficulty of this particular distribution has been encountered in the past and resulted in bilateral mastectomies. The authors describe successful treatment of a patient with hidradenitis suppurativa of the breasts and nipple-areolar complexes using breast-conserving measures. Normal breast contour was preserved and overall cosmetic result was good.
    No preview · Article · Mar 2004 · Annals of Plastic Surgery

  • No preview · Article · Mar 2004 · Plastic & Reconstructive Surgery