Despite the different underlying aetiologies, most chronic wounds show a similar behaviour and progress. This uniformity is due to consistent components of the multifactorial pathogenesis of most chronic wounds: local tissue hypoxia, bacterial colonisation, repeated ischemia-reperfusion injury and cellular as well as systemic changes of ageing (Diegelmann and Evans, 2004). Also, as the name suggests, pressure ulcers occur due to high levels of sustained pressure and/or long periods of unrelieved pressure. As a result, there is a reduction in the blood supply to the skin and underlying tissue and potential damage or hypoxia to the underlying microcirculation and tissue