Suprathel, a new skin substitute, in the management of donor sites of split-thickness skin grafts: results of a clinical study.

OBJECTIVE: A prospective, randomized, two center clinical study was conducted to evaluate the impact on wound healing of Suprathel in donor sites of split-thickness skin grafts. Suprathel represents an absorbable, synthetic wound dressing with properties of natural epithelium. METHODS: 22 burn patients who were treated with split-thickness skin grafts, and with a mean age of 39.6 years were included in the study. Donor sites of skin grafts were randomly selected; partly treated with Jelonet and partly treated with Suprathel. First gauze change was carried out the fifth day postoperatively followed by regular wound inspection until complete re-epithelization. The study focused on patient pain score, healing time, analysis of wound bed, ease of care, and treatment costs. RESULTS: There was no significant difference between the two materials tested regarding healing time and re-epithelization. There was a significantly lower pain score for patients treated with Suprathel (p=0.0002). Suprathel became transparent when applied and allowed close monitoring of wound healing. In contrast to Jelonet, Suprathel showed excellent plasticity with better attachment and adherence to wound surfaces. Throughout the healing process it detached from wounds without damaging the new epithelial surface. In addition, wound areas treated with Suprathel required less frequent dressing changes. It also demonstrated excellent ease of care. This, altogether with the significant pain reduction, presented a positive feedback by patients and healthcare professionals who both rated Suprathel as their treatment preference. Though Jelonet is more cost effective as dressing material, the study revealed an overall reduction in total treatment costs achieved with Suprathel. CONCLUSION: Suprathel represents a solid, reliable epidermal skin substitute with impact on wound healing, patient comfort and ease of care. The material effectiveness contributes to the reduction of overall treatment costs.

Suprathel-an innovative, resorbable skin substitute for the treatment of burn victims.

Autologous split skin grafts are the most reliable method for closing third degree burns. Under this scheme, donor sites as well as second degree burns under conservative treatment, however, would benefit from rapid wound closure. For this treatment, biological as well as synthetic materials are available. For the improvement of these materials, primary goals are pain reduction and easy handling in the absence of biological risk. From a synthetic copolymer mainly based on DL-lactic acid a new skin substitute was developed, marketed as Suprathel. Within the scope of a bicentric study Suprathel was compared versus paraffin gauze intraindividually applied on split skin donor sites. Wound pain was measured on the Visual Pain Analog Scale over a period of 10 days as the critical criterion. Accordingly Suprathel versus Omiderm were compared on second degree burns (degree 2a, partial thickness burns). In both study parts, Suprathel significantly reduced pain. Its easy handling was superior compared to other materials. The Suprathel membrane adhered rapidly to the wound thus protecting against infections and promoting wound healing. No allergic reactions were observed. The ability of the material to resorb ensured pain-free removal after complete healing of the wound.

A new technique for reconstruction of the common bile duct by an autologous vein graft and a biodegradable endoluminal stent.

The incidence of severe bile duct injuries has significantly increased since the introduction of laparoscopic cholecystectomy. The ideal reconstruction procedure for traumatic defects of the bile duct should be technically simple and should preserve both the physiological passage of bile and the sphincter of Oddi. In this article we describe a new technique for bile duct reconstruction in a pig model by means of an autologous vein graft that is splinted by a endoluminal biodegradable polylactate acid stent. In 12 pigs the external jugular vein was removed and used as an autologous vein graft. After performing a median laparotomy a 2-cm segment was resected from the bile duct. The common bile duct was reconstructed by a venous interponate that had been endoluminally stented by a biodegradable polylactate acid stent. For the examination of stent degradation, 2 pigs were sacrificed at 3, 4, and 5 months (stent degradation group) and the remaining 6 pigs at 6 months (survival group). All the pigs in the survival group survived for 6 months before being sacrificed. After 4 months the stent material had been completely broken down and the vein graft had been relined with bile duct epithelium. Thus, this new technique for bile duct reconstruction using an autologous vein graft with an endoluminal stent is simple to perform and reliable, and constitutes an interesting alternative to bilodigestive anastomosis due to the preservation of the papilla of Vateri.

[Reconstruction of bile duct lesions by an autologous vein graft and a bio-degradable endoluminal stent in an animal model: technique and clinical impact]. / Rekonstruktion von Gallengangsdefekten mit autologem Veneninterponat und resorbierbarem Stent im Tiermodell: Technik und klinische Bedeutung.

INTRODUCTION: In this study a new treatment of bile duct lesions was investigated. A segment of the bile duct was replaced by an autologous venous interponate which had been endoluminally stented with a braided bio-degradable stent. METHODS: A total of 18 pigs (20-28 kg) was divided into three equal groups (I-III). In each group a 2 cm segment of the jugular vein was harvested. The animals in Group I (vein group, n = 6) underwent resection of a 2 cm long segment of the common bile duct which was replaced solely by the venous interponate, in Group II (stent group, n = 6) the venous interponate had been endoluminally stented by a braided bio-degradable stent. Group III (control group, n = 6) underwent only a circular mobilization of the common bile duct. Postoperatively survival rate, general condition as well as the weight were observed and checked for 6 months. During surgery and finally after sacrifice after 6 months blood and tissue samples were taken and semiquantitatively scored concerning grade of inflammation and fibrosis. RESULTS: In the stent and control group all animals survived in good condition. 3 pigs of the vein group died within 3 weeks showing signs of biliary peritonitis, another one died due to a high grade stenosis of the common bile duct with secondary biliary cirrhosis after 4 months. In the stent group all animals survived until sacrifice after 6 months. On examination the venous interponate was laminated with bile duct epithelium showing the diameter of the implanted stent. CONCLUSION: The reconstruction of bile duct lesions by a venous interponate in combination with a bio-degradable stent is easy to perform and represents a clinically interesting alternative to the biliodigestive anastomosis because of the preservation of the sphincter oddi. After 6 months the stent is completely absorbed and the venous interponate is laminated with bile duct epithelium.

Resorbable polymer fibers for ligament augmentation.

Resorbable augmentation devices for cruciate ligament surgery have been developed to temporarily protect healing tendon grafts or sutured ligaments against high tensile loads during the postoperative healing period. Materials available at present [e.g., polydioxanone (PDS)] show a half-life tensile strength of only 4-6 weeks, whereas the process of revitalization and recovering of the transplanted tendon graft can take up to 12 months. Therefore, a device that provides gradually decreasing mechanical properties with a half-time strength of at least 6 months would be desirable. In order to obtain a suitable material, we investigated the degradation kinetics of a variety of different resorbable fibers made of poly(L-lactide) and poly(L-lactide-co-glycolide). The fiber materials differed in processing and treatment parameters like thermal posttreatment, irradiation, and fiber diameter. The fibers were degraded in vitro and were tested for mechanical properties and molecular weight at various time points up to 72 weeks. The half-time strength of the materials ranged between 5 and 64 weeks, depending on their treatment parameters. In contrast, the stiffness did not decrease adequately. However, an augmentation stiffness that does not change much versus time could not provide a gradual increase in graft load, which is important to stimulate the orientation of the collagenous tissue. Therefore, design of an augmentation construct braided out of more than one quickly degrading fiber materials is suggested. After the breakdown of the faster-degrading fiber components the stiffness would automatically decrease by the diminution of the load-carrying fiber volume.

Alveolar ridge repair using resorbable membranes and autogenous bone particles with simultaneous placement of implants: an experimental pilot study in dogs.

The aim of this experimental study was to evaluate the use of autogenous bone harvested during preparation of implant sites in combination with resorbable membranes for vertical ridge augmentation under 2 different defect site conditions. Combined vertical/horizontal alveolar bone defects were created by experimentally induced periodontal infections around all premolar teeth in the mandibles of 3 dogs (group 1). In another 3 dogs, fresh surgical defects were created after extraction of all premolar teeth in the mandibles (group 2). In all dogs, 2 implants were placed on each side of the mandible into the defect areas. One implant on each side of the mandible received augmentation with autogenous bone particles, and both implants on one side of the mandible were covered with polylactic acid membranes. After 5 months, the material was evaluated histologically. There was a small but significant increase in bone regeneration in the defects augmented with bone particles with and without membrane coverage in group 1. In group 2, no significant difference was seen between the controls and the augmented sites. The major limiting effect for bone regeneration appeared to be insufficient stability of the bone material to withstand the overlying soft tissue pressure. It was concluded that the placement of autogenous bone particles, either with or without membrane coverage, had little effect on the regeneration of peri-implant bone defects.

Guided bone regeneration around endosseous implants using a resorbable membrane vs a PTFE membrane.

The aim of the present experimental pilot study was to assess bone regeneration underneath resorbable barrier membranes vs non-resorbable extended polytetrafluoroethylene (ePTFE) membranes in peri-implant defects. Two implants were inserted into surgically created defects on each side of the mandibles of 6 adult beagle dogs 3 months after extraction of all premolar teeth. One implant on each side was covered with a porous polylactic acid membrane or a ePTFE membrane, respectively, while the second implant served as control. Fluorochrome labelling was administered during the 1st, 5th, 12th and the 18th week. Three animals each were evaluated after 3 and 6 months. Bone regeneration was assessed by measuring the distance from the first fluorochrome label to the level of the regenerated bone immediately adjacent to the implant surface and to the top of the newly formed alveolar contour both on the lingual and buccal side. The increase in bone height was significantly higher compared to the controls under both barrier membranes after 3 months at the top of the alveolar crest but not immediately adjacent to the implant surface. After 6 months, bone height was significantly increased only at the top of the alveolar contour underneath the ePTFE membranes, while bone underneath the polylactic acid membranes showed signs of superficial resorption. It is concluded that guided bone regeneration underneath barrier membranes can restore alveolar bone contour but is not necessarily associated with a higher bone/implant contact. The use of resorbable membranes may be associated with untoward biological effects at later stages, when membrane degradation starts due to degradation products of the polymer material or decreasing membrane stability. Future efforts have to refine the relation between degradation kinetics, membrane porosity and mechanical properties of degradable barrier membranes to improve membrane performance.

Resorbable polyesters in cartilage engineering: affinity and biocompatibility of polymer fiber structures to chondrocytes.

The resorbable polymers polyglycolic acid (PGA) and polylactic acid (PLA) are gaining increasing importance in tissue engineering and cell transplantation. The present investigation was focused on the biocompatibility and cell retaining behavior of PGA/poly-L-lactide (PLLA) (90/10) and PLLA nonwoven structures for the in vitro development of chondrocyte-polymer constructs. The effect of the relevant monomers to chondrocytes was analyzed. Type II collagen and poly-L-lysine were compared to improve loading of PGA/PLLA and PLLA polymer nonwovens with chondrocytes. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetra-zoliumbrom ide (MTT) test was applied for quantification. At concentrations above 2 mg/mL, glycolic acid was more cytotoxic than lactic acid. As shown by pH equilibration, the cytotoxic effect is not due merely to the acidity of the alpha-hydroxy acids. Regarding the degradation products, glycolic acid, and L(+) lactic acid, nonwovens of PLLA are more biocompatible with chondrocytes than nonwovens of polyglycolide. Collagen type II and poly-L-lysine generally improved cell seeding on resorbable polymers in tissue engineering; however, their efficiency varies depending on the type of fiber structure.