MARCO ISLAND, FL-Doctors suggest that an new artificial skin product-already approved for the treatment of patients with major burns and other injuries-could have application for repair of large head and neck surgical wounds.
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April 2007A description of the product, which is approved by the Food and Drug Administration, was presented by Kapil Saigal, MD, a resident in otolaryngology-head and neck surgery at Thomas Jefferson University in Philadelphia, at the first combined meeting of the four geographical sections of the Triological Society.
Dr. Saigal said the product-Integra Dermal Regeneration Template for Skin Replacement (Integra Lifesciences, Plainsboro, NJ)-as well as other biomaterials, such as cadaver allograft skin, xenographic skin, and bioengineered skin substitutes, may be able to span the gap between skin grafting and free tissue grafting.
Skin grafts are fragile, especially when placed on areas where there is little underlying soft tissue for support, said Dr. Saigal. Skin grafts often cannot tolerate radiation; they tend to contract; they contain abnormal pigmentation; and patients are prone to donor site complications.
These grafts are more functional than cosmetic, he noted.
The dermal template allows for ingrowth of fibroblasts, macrophages, and epithelial cells into the wound bed. In addition, a top layer of the template prevents moisture loss just like the native epidermis.
-Kapil Saigal, MD
Advantages of New Biomaterials
The new-generation biomaterials-used either as a short-term or permanent replacement until normal skin regeneration occurs-appear to overcome most of the drawbacks and complications that occur with skin grafts.
The Integra product is not well known to us in head and neck surgery, said John Rhee, MD, Associate Professor of Otolaryngology at the Medical College of Wisconsin in Milwaukee. That is one reason we wanted to hear this report and why we included it on the program.
Dr. Rhee noted that the report generated questions from the audience who were interested in the device and how it could be used in practice.
It certainly looks like a promising use for patients with large wounds, Dr. Rhee said. However, like all new products brought to the market, we will need further studies, including comparative studies against standard practices so we can judge how well it performs as far as outcomes and complications are concerned.
In making the case for use of the artificial skin, Dr. Saigal said that it appears Integra has numerous advantages over standard skin graft treatments:
- It improves cosmetics outcomes by reducing scarring.
- It allows for immediate closure over muscle, cartilage, and fascia.
- There is less tissue manipulation required.
- Donor site morbidity is reduced.
- Operative time is decreased.
- The area being repaired returns to normal function more quickly.
- The need for surgeons to prematurely commit to labor-intensive reconstructions is lessened.
Biological skin substitutes decrease bacterial counts, slow loss of water, protein and electrolytes, reduce pain and help restore function. In addition these skin substitutes can prevent the dessication of nerves, blood vessels, and tendons. Dr. Saigal said. The mainstay of research and development of these biological skin substitutes is for use in wound healing and burns. They represent a new experience in reconstructive head and neck surgery. There is less experience in reconstruction but it does provide us with a multitude of new options.
Mechanisms of Function
Dr. Saigal said that the product was initially approved by the FDA in 2001. Integra consists of a 100-micrometer-thick epidermis layer of polysiloxane, a three-dimensional porous matrix of cross-linked bovine tendon type I collagen, and glycosaminoglycan. The Integra sheet is placed on the wound and is sutured into place along the sides and the center, Dr. Saigal explained when asked by doctors to more fully describe how it works. The dermal template allows for ingrowth of fibroblasts, macrophages, and epithelial cells into the wound bed. In addition, a top layer of the template prevents moisture loss just like the native epidermis, he said.
Eventually the original template degrades and can be easily removed after two to three weeks. He said that the results show superior cosmetic results when compared to outcomes seen with split-thickness skin grafts.
Exactly how the process works to build new skin, Dr. Saigal said, is still not completely understood. It is believed that improved cell migration is enhanced by fibroblast proliferation and that glycosaminoglycans bind to tissue growth factors, suppressing the inflammatory phase of wound healing. The tissue formed has a high density of blood vessels that actually resembles normal dermis, with the exception of sebaceous glands and follicles, he said.
He illustrated one patient with a nasal growth that required massive excision that included considerable anatomic structures, yet the outcome appeared virtually normal. In head and neck surgery, we envision using Integra for surgical defects not amenable for closure due to their size or location, in radiated fields, for improved skin graft survivability, for conventional cancer excision where tissue margins have been deferred to permanent section, and for patient in extremes of age-young children or the elderly-where rapid healing is desirable, he said.
Future Uses
Looking to the future, Dr. Saigal predicted that the Integra template would find uses in head and neck surgery in such areas as nasal reconstruction, where there is nasal vestibular stenosis; in cases where the internal nasal lining has been destroyed or is compromised; and in repairing forehead flap donor site wounds. He said that Integra templates could also help in the repair of radial arm free flap donor sites and the material would be helpful in closing large neck wounds that are resistant to repair.
In reviewing treatments for radiated scalp wounds, Dr. Saigal found a high rate of complications in patients who underwent split-thickness skin grafts. However, patients with similar wounds had better results in case series with Integra. He cited studies that showed that when combined with vacuum-assisted closure dressing in complicated wounds-wounds that included exposure to the bone and tendon-Integra application resulted in a 96% split-thickness skin graft take rate after an average of 7.25 days. Another study suggested that when combined with fibrin glue, the take rate increased to 98% at 10 days compared with a 78% take rate among controls. Skin graft transplantation was possible in an average of 11 days with Integra, compared with 24 days for controls.
Dr. Saigal observed that there are also possible downsides with the new product, including the requirement for possible staged procedures; the need to keep the wound dry for four to six weeks; the cost of the material-an 8-by-10 inch sheet of the material may cost as much as $2,000; the short one- to three-week shelf life; and the potential of introducing undetected pathogens or allergic reactions to bovine collagen-although none have been reported. He did not report any conflict of interest in regard to his presentation.
©2007 The Triological Society