the healing of venous ulcers, however more research is necessary to confirm these results. Treatments aimed at decreasing protease activity to promote healing in chronic wounds have been suggested, however, the benefit remains uncertain. There is also lack of evidence on effectiveness on testing for elevated proteases in venous ulcers and treating them with protease modulating treatment. There is low certainty evidence that protease modulating matrix treatment is helpful in the healing of venous ulcer. Flavonoids may be useful for treating venous ulcers but the evidence needs to be interpreted cautiously. Wound Cleansing Solutions There is insufficient evidence to determine if cleaning wounds is beneficial or whether wound cleaning solutions (polyhexamethylene biguanide, aqueous oxygen peroxide, etc.) are better than sterile water or saline solutions to help venous leg ulcers heal. It is uncertain whether the choice of cleaning solution or method of application makes any difference to venous leg ulcer healing. Skin grafts and artificial skin Two layers of skin created from animal sources as a skin graft has been found to be useful in venous leg ulcers. Artificial skin, made of collagen and cultured skin cells, is also used to cover venous ulcers and excrete growth factors to help them heal. A systematic review found that bilayer artificial skin with compression bandaging is useful in the healing of venous ulcers when compared to simple dressings. Surgery A randomized controlled trial found that surgery "reduces the recurrence of ulcers at four years and results in a greater proportion of ulcer free time". Local anaesthetic endovenous surgery using the thermoablation (endovenous laser ablation or radiofrequency), perforator closure (TRLOP) and foam sclerotherapy showed an 85% success rate of healing, with no recurrence of healed ulcers at an average of 3.1 years, and a clinical improvement in 98% in a selected group of venous leg ulcers. No studies are found on the effect of endovenous thermal ablation on ulcer healing, recurrence, and quality of life. The use of subfascial endoscopic perforator surgery is uncertain in the healing of venous ulcer. Dressings It is not certain which dressings and topical agents are most effective for healing venous leg ulcers. Silver-containing dressings may increase the probability of healing for venous leg ulcers. A clinical trial was successfully performed with a mixture of 60% sugar or glucose powder and 40% vaseline. A 2013 Cochrane systematic review aimed to determine the effectiveness of foam dressings for helping