Exploring The Potential Of Advanced Wound Care Products For Diabetic Wounds
- Volume 26 - Issue 12 - December 2013
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However, with the graft form of amniotic membrane, controversy exists as to which side should face the wound, the amniotic or chorionic side. In a study of sheep, Trelford and colleagues showed an immunological response when the chorionic side faced the wound.16 Such a response suggested maternal decidual fragments may inadvertently accompany the chorion. Robson and coworkers studied “vascular invasion” and recommended not separating the chorionic surface from the amnion in order to see vascularization.17
Lim and coworkers compared the biological and ultra-structural properties of the dehydrated human amniotic membrane and cryopreserved human amniotic membrane cellular components, and biochemical composition with respect to ocular surface disease that required resurfacing with human amniotic membrane.20 They found that although there are significant differences in composition and ultrastructure between the two forms, they do not appear to compromise cell survival in vivo.
Zelen and colleagues compared healing characteristics (wound reduction and rates of complete healing) of dehydrated human amniotic membrane (EpiFix, MiMedx) versus standard of care in indolent neurotrophic diabetic ulcers.5 Researchers applied EpiFix every two weeks until complete healing and did not exceed 10 weeks. Ninety-two percent of chronic diabetic foot ulcers healed over a six-week period in comparison to only 8 percent with standard of care alone.
Werber and colleagues studied 20 patients with foot ulcers due to diabetes and arterial insufficiency that had been recalcitrant to treatment for over a year.19 These wounds displayed undermining and/or sinus tract or tunneling. The study used the cryopreserved allograft form AmnioMatrix (Applied Biologics), a mixture of amniotic membrane and amniotic fluid, which is intended for treatment of wounds. At 12 weeks, 18 of 20 patients experienced 100 percent wound closure and the undermining/tunneling of the wound was the first to respond to AmnioMatrix. Reductions in wound volume and area followed.
How To Apply Amniotic Membrane
As always, sharp debridement and appropriate preparation of the wound bed are absolutely necessary. Amniotic membrane comes in liquid form, in powder form (that one can mix with saline for injection) and as a graft. When using the injectable form, make the injection in the periwound area about 0.5 cm from the wound edge and directly into the superficial fascia and subcutaneous tissue of the wound at the 12, 3, 6 and 9 o’clock positions of the wound. The needle should be parallel to the wound margin at each location and one should deposit equal amounts at each site at about 10 to 15 mm in depth.
After application, apply a non-adhesive dressing followed by a dry, sterile dressing. The graft form comes in different sizes that one can cut to fit the wound. Graft orientation is important. The epithelial layer should be on top and dressed with non-adherent dressing. Do not disturb the graft form for at least two weeks.
One should follow any form of application with supportive therapies such as offloading and compression if necessary.5,19
Amniotic membrane has numerous indications and very few contraindications with infection being the main contraindication. Wounds require adequate vascularity to heal regardless of any treatment plan as well as proper offloading. Amniotic membrane is no exception. The fact that amniotic membrane is non-immunogenic and anti-inflammatory with decreased pain and scarring, provides a matrix for cell colonization and acts as a natural barrier makes human allograft ideal for wound treatment in many types of patient. Currently, amniotic membrane is still undergoing research and more robust studies need to be performed. However, amniotic membrane is definitely another tool in the foot and ankle surgeon’s armamentarium when clinicians use it appropriately along with good local wound care.
Dr. Perez is a third-year resident in Podiatric Medicine and Surgery at the New York College of Podiatric Medicine/Metropolitan Hospital/Lincoln Hospital. She is a Fellow of the New York Academy of Medicine.