A 74 year old male suffered a burn to his lower leg 15 years ago which was treated with debridement and skin graft. Past medical history of non-insulin dependent diabetes for 30 years, hypertension, and coronary artery disease. His leg wound has always required some dressings and has never completely healed. It has recently changed and become more open and friable, and has increased drainage. What is the most the most appropriate next step in his management is