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Edge of Wound - Non advancing or undermined


Despite best efforts, some wounds fail to heal, and the most obvious sign of this is the failure of the epidermal margin or “edge” to migrate across the wound bed. The margin may even be undermined, a sign that often indicates critical colonisation or infection. At a cellular level, the lack of epidermal migration is due to non-responsive wound cells and abnormalities in protease activity that degrade the extra cellular matrix while it is formed. If the principles of wound bed preparation have already been successfully applied (remove non-viable tissue, treat infection and or inflammation, restore bacterial moisture balance), then a re-assessment of patient factors should be carried out.


During the normal process of wound healing, a series of molecular events prepares the wound for repair, deposition of new extracellular matrix and, eventually, complete wound closure. This orderly process of cellular control appears to be impaired in chronic wounds, which results in a delay or failure of the repair process. For example, wounds such as venous ulcers and leg ulcers, are characterised by the defective remodelling of the extracellular matrix, a failure to re-epithelialise and prolonged inflammation.


Problems with Cellular Migration
It has recently been demonstrated that the epidermis in chronic wounds, such as venous and pressure ulcers, fails to migrate across the wound bed, and that there is widespread hyperproliferation associated with the chronic wound margin. It is believed that this hyperproliferation interferes with normal cellular migration over the wound bed and results from the inhibition of apoptosis, or normal programmed cell death, within the fibroblast and keratinocyte cell populations.


Achieving Vascularisation
It is important to ensure adequate tissue perfusion, as a wound will not heal if the wound bed is not well vascularised. This may require correction of abnormalities or adjustment of co-medications for other conditions. Host resistance to bacterial infection may be significantly lowered as a result of coexisting conditions, poor nutrition, or bad lifestyle. There are also many host factors that can impair wound healing, such as: ischemia, diabetes mellitus, malnutrition, alcoholism, cardiac failure, respiratory disease, renal failure, hepatic dysfunction and the use of immunosuppressive drugs. If the patient is in optimal health but the wound still fails to heal, it may require the application of advanced techniques in order to begin the healing process. Other treatment options are available, such as skin grafting and biological and adjunctive therapies, all of which require a well prepared wound bed to be successful.