Exploring The Potential Of Acellular Dermis Grafts For Wound Healing And Soft Tissue Repair

J. Palmer Branch, DPM, FACFAS

   An ideal graft should not be reactive to the recipient tissue and facilitate ingrowth of new tissue (i.e. serve as a scaffold). Basically, the theory is that acellular dermis grafts can be transformed into tissue similar to the recipient tissue in which it is placed. Such tissue may be skin, tendon, ligament or, theoretically, cartilage.3,7,11

What You Should Know About The Processing Of Acellular Dermis Grafts

The grafts undergo various chemical processes and freeze drying to remove the cellular components to minimize the risk of graft rejection. Every manufacturer has subtle differences in graft processing. Processing variations slightly alter graft handling and behavior clinically, leading to surgeon or facility graft preferences. Some grafts require refrigeration while others allow room temperature storage. The varying evidence of success in clinical studies may also affect surgeon preferences. Prior to application in the operating room, the grafts are typically thawed (a.k.a. reconstitute) in normal saline.

A Guide To Surgical Applications

Acellular dermis grafts come in many sizes and thicknesses. Generally, thinner grafts are for wounds or small tendon repair, and incorporate more rapidly. The thicker grafts have more tensile strength but incorporate more slowly.

   Surgical applications are not limited to the foot and ankle. The applications include:
• wounds (surgical, diabetic foot, traumatic, venous stasis ulcers and others)7
• tendon repair (wrap or weave techniques)12
• joint resurfacing (first metatarsophalangeal joint, ankle joint)11
• oral surgery (gingival augmentation and cleft palate repair)
• ligament repair
• hernia repair
• soft tissue supplementation (plastic surgery and plantar soft tissue)
• burn wounds
• leg fascia repair
• rotator cuff repair9,13,14
• hernia repair
• breast reconstruction (post-mastectomy)

Assessing The Efficacy Of Dermis Grafts In Wound Healing

Historically, donor dermis grafts were used primarily on burn wounds. These grafts were traditionally removed once the wound healed sufficiently below the graft to be a good recipient bed for split-thickness skin graft application. In recent years, the acellular dermal matrix grafts are left in place to allow a scaffold effect for new tissue ingrowth. This ability is facilitated by the microscopic framework of the grafts that have retained structural components including vascular channels. This author likes to think of the acellular dermis grafts as a means to improve the quality of the wound bed to facilitate epithelialization.

   The grafts are often meshed prior to application for wounds to help prevent hematoma and seroma formation as well as to increase the wound surface area that the graft can cover. The graft is then applied with the reticular side against the wound. To help identify the reticular side, a drop of blood can be placed on the graft and observation for more rapid resorption on the reticular side.

   Use of negative pressure therapy (e.g. Vacuum Assisted Closure {VAC, KCI}) can enhance acellular dermis graft incorporation.15-17 The benefits of VAC Therapy include enhanced graft wound bed adherence, wound volume reduction, localized hyperemia, microstrain on wound cells (stimulates granulation), angiogenesis stimulation and wound exudate removal.

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