The time to wound-healing is analyzed using Cox regression analysis. An intent-to-treat principle will be applied in the analysis. Patients' time-to-wound-healing are censored at the time of consent withdrawal, dead or lost to follow up. The difference between the two arms is assessed using Cox model. Repeated measures ANOVA is performed to compare the effects of intervention (vs. control) and time (6 week post randomization) on mean wound size change. The differences in wound symptoms and patient's satisfaction and comfort to cleansing method are analyzed using Wilcoxon Rank Sum Test. Chi-square test is used to test difference in the infection incidence and the proportion of wounds completely healed during follow up between the two groups. Prognostic factors are assessed and adjusted using a Cox proportional hazard regression model. These variables are: age, body mass index (calculated from participants' height and weight), wound characteristics (location, types, wound size), wound status (assessed by Wound Status Assessment score), smoking, presence of underlying disease, concomitant medication and mental status (assessed by AMT).