What You Should Know About Skin Grafts And Skin Substitutes

Skin grafts and skin substitutes can play key roles in facilitating lower extremity wound healing. Accordingly, these authors share their thoughts on the preparation and application of these modalities, and provide keys to effective post-op care.

Q:

Do you have any preference to “living cell” skin substitutes, other skin substitutes and graft replacements?

A:

Kazu Suzuki, DPM, CWS, uses various skin substitute products based on the size of the wound, the patient’s insurance coverage and the product’s FDA indications. In regard to the two living cell skin substitutes, he notes Apligraf (Organogenesis) is indicated for diabetic foot and venous ulcers whereas Dermagraft (Advanced BioHealing) is only indicated for diabetic foot ulcers. Although the living cell products work well, Dr. Suzuki says they are expensive and one must order them in advance.

   While practicing at the University of Texas Health Science Center at San Antonio’s Diabetes Institute, Kathleen Satterfield, DPM, had a lot of experience with Apligraf. She notes that she saw such a positive response with Apligraf that it became her “go-to” product for diabetic foot wounds very early in treatment. Dr. Satterfield also cites emerging literature that recommends the consideration of advanced modalities if there is not a 50 percent or greater reduction in diabetic foot ulcer size at four weeks.1,2

   In the end, she notes the wound will heal much faster and thousands of dollars will be saved in the long run, an effect Dr. Satterfield saw repeatedly in her time at the University of Texas. However, Drs. Satterfield and Suzuki both emphasize appropriate use of living cell skin substitutes in properly selected patients. Eric Lullove, DPM, adds that “the use of living cell (products) should only be reserved for those patients who do not forcibly bleed and do not have the proper amount of growth factors at their wound bed to promote healing.”

   Dr. Suzuki notes that other “off-the-shelf” products do not contain living cells but still supply collagen scaffold and growth factors to the wound bed.

   Dr. Lullove sees “no difference” between living cell products and other skin replacement products. He feels most patients who have a decent arterial supply will be able to utilize the product for its intended use: to penetrate type I or type III collagen to the wound bed to stimulate fibroblast proliferation.

Q:

How do you prepare and secure your skin grafts or skin substitute to the wounds?

A:

Dr. Suzuki meshes or fenestrates all skin grafts and skin substitutes prior to application. Desmond Bell, DPM, will use a mesher for skin grafting. When it comes to Apligraf, Dr. Bell fenestrates the graft using a scalpel blade and notes that #10, 11 or 15 blades will work equally well. He notes the fenestration helps stimulate the product to facilitate the release of growth factors while also allowing for mild exudate to drain between the ulcer and the graft. However, Dr. Bell does not mesh Apligraf as it is not a skin graft. He adds that Dermagraft does not require fenestration or meshing.

   For larger or uniquely shaped wounds, Dr. Suzuki prefers using the VAC GranuFoam dressing (KCI) with a continuous setting of 100 mmHg and a nonadherent layer with Mepitel or Mepitel One (Molnlycke Healthcare). For complex wounds, he employs a skin flap secured with incisional VAC therapy (KCI) as well as a skin graft secured with VAC therapy, which bolsters and drains the reconstructive surgery site. On the other hand, Dr. Suzuki notes one may secure smaller wounds with a small piece of skin graft/substitute with Steri-Strips, sutures, staples or a combination of those with compressive dressing.

   Dr. Satterfield prefers stapling grafts in place while Dr. Bell never uses staples on skin grafts. Instead, he prefers using Steri-Strips and covering the graft with Mepitel, a porous, silicone adherent, non-stick dressing. When Mepitel is not available, he suggests using Adaptic (Systagenix Wound Management), Wound Veil (Smith and Nephew) or Xeroform (Kendall Healthcare). Dr. Satterfield also uses Mepitel on top as a non-adherent dressing along with and saline moistened gauze. She says the wound environment should be moist but not wet. Dr. Satterfield subsequently applies Kerlix and Coban™ (3M) dressing.

   Dr. Lullove secures all his skin grafts with 4-0 chromic gut suture with a mineral oil-cotton occlusive dressing. Depending on the skin substitute, he usually fixates them with Steri-Strips and employs heavy 3-0 Vicryl suture (Ethicon) for products such as PriMatrix (TEI Biosciences) and Integra (Integra Life Sciences). At times, Dr. Lullove has used surgical staples to anchor a graft to a wound bed.

   To secure the skin grafts, Dr. Bell suggests using a bolster dressing comprised of Xeroform, saline moistened gauze and gauze wrap. Then he employs evenly spaced long sutures around the periphery of the dressing and ties over the top in the middle. Dr. Bell advises that the anatomical location of the wound will dictate the type of protective outer dressing and whether compression is required as in the case of venous leg ulcers.

Q:

What is your post-op for skin graft or skin substitute?

A:

Dr. Lullove says post-op care for all skin grafts and skin substitutes is relatively the same in his view. Essentially, one should preserve as much of the graft tissue as possible, according to Dr. Lullove. He notes a high rate of collagen degradation occurs as a natural part of hydrolysis and wound graft interaction. Dr. Lullove suggests checking graft sites at days three, seven and 14. He most commonly uses a hydrogel Adaptic Xeroform dressing, which provides occlusion and keeps the graft tissue hydrated.

   Dr. Satterfield notes the importance of experience for post-op care. She recalls seeing an Apligraf post-placement, which was fibrinous slough, that she thought had broken down and needed debridement. She advises caution in such situations, saying that slough is the material that contains the rich cellular mix that invests itself into the wound bed to create the necessary regrowth. Similarly, Dr. Lullove emphasizes that any kind of debridement of a grafted wound is contraindicated and basically removes the collagen from the environment that one is trying to heal.

   Dr. Satterfield advises leaving the post-placement dressing alone for a week, keeping it clean and dry. After that, she says one should monitor for infection just as you would for any post-op case. If necessary, she suggests placing a second skin substitute, calling this “wound food.

    “You are inoculating the wound with nutrients and you may need to do so a second time,” says Dr. Satterfield. “This is no time to be nervous and go halfway and no further. Get your patient the whole way home.”

   For a skin graft, Dr. Suzuki removes VAC therapy after five to seven days. He then applies some kind of non-adherent dressing such as Mepilex, which patients change once a week until the skin graft “takes” and there is complete epithelialization.

   For skin substitutes, Dr. Suzuki notes each product has a different protocol of re-application. For example, the manufacturers of Dermagraft and Oasis (Healthpoint) recommend that one apply such products once a week while Apligraf’s recommended application is every two weeks. Even though the global periods may change from year to year, these re-application schedules are widely used today, according to Dr. Suzuki.

   Dr. Suzuki notes that “-58” is the most commonly used modifier. He says this indicates a “staged procedure” performed during the global period of these skin substitutes as the wound healing process is a “staged” process as opposed to a single-stage wound closure, such as primary closure with skin flap.

    “For the re-application process, I would try not to debride or disturb the ‘old’ adherent graft, but simply irrigate the old graft and remove only the loose fragments that did not ‘take’ to the wound bed,” suggests Dr. Suzuki. He says one should place the ‘new’ graft and secure it right over the old graft after the wound bed is irrigated and prepared.

    “You may be tempted to ‘double up’ a leftover graft on smaller wounds but it has not been shown to be beneficial so far, probably for the same reason that doubling up a partial-thickness skin graft does not really help in wound healing,” adds Dr. Suzuki.

   Dr. Satterfield monitors autografts for infection and seroma, calling those the “biggest potential problems.” She suggests placing VAC therapy on the surface of the fenestrated autograft after one has stapled the autograft in place. As she notes, VAC therapy will increase the percentage of “take” and the time required for it to happen.

   For Dr. Bell, post-op care depends primarily upon the location and etiology of the ulcer. For a diabetic foot ulcer on an ambulatory patient, he says strict offloading is critical. His practice uses total contact casting, soft casting and pre-screening for patient comprehension and adherence to keep the graft/ulcer protected at all times. In addition, Dr. Bell says venous leg ulcers typically require some type of compression dressing to assist in managing edema.

   Between dressing changes, Dr. Bell notes one should perform gentle irrigation with normal saline and periodically change the primary dressing (Mepitel, Vaseline gauze). He notes the timing of this depends on the degree of drainage. He does not use silver dressings or other potentially cytotoxic compounds on grafts of any kind.

   Dr. Bell is a board certified wound specialist of the American Academy of Wound Management and a Fellow of the American College of Certified Wound Specialists. He is the founder of the “Save a Leg, Save a Life” Foundation, a multidisciplinary, non-profit organization dedicated to the reduction of lower extremity amputations and improving wound healing outcomes.

   Dr. Lullove is in private practice in Boca Raton and Delray Beach, Fla. He is a staff physician at West Boca Medical Center in Boca Raton. Dr. Lullove is a Fellow of the American College of Certified Wound Specialists.

   Dr. Satterfield is an Associate Professor at the Western University College of Podiatric Medicine in Pomona, Calif. She is a Fellow and President-Elect of the American College of Foot and Ankle Orthopedics and Medicine.

   Dr. Suzuki is the Medical Director of Tower Wound Care Center at the Cedars-Sinai Medical Towers. He is also on the medical staff of the Cedars-Sinai Medical Center in Los Angeles and is a Visiting Professor at the Tokyo Medical and Dental University in Tokyo, Japan.

References:

1. Margolis DJ, Allen-Taylor L, Hoffstad O, Berlin JA. Diabetic neuropathic foot ulcers: the association of wound size, wound duration, and wound grade on healing. Diabetes Care. 2002; 25(10):1835-9. 2. Snyder RJ, Kirsner RS, Warriner RA 3rd, Lavery LA, Hanft JR, Sheehan P. Consensus recommendations on advancing the standard of care for treating neuropathic foot ulcers in patients with diabetes. Ostomy Wound Manage. 2010; 56(4 Suppl):S1-24.