Refractory wounds are ulcers that are difficult to heal on their own for various reasons. As you know from the name, treatment of refractory wounds is very difficult. The condition of the ulcer can be improved, the secretion is reduced, and the granulation becomes fresh through treatments such as drug exchange, negative pressure vacuum suction, and topical application of various drugs, but the ulcer is still difficult to heal on its own. In this case, it is repaired by plastic surgery such as skin grafting, flap grafting, and myocutaneous flap grafting. Although refractory ulcers are not immediately life-threatening, the quality of life of the patient is seriously affected by the long-lasting trauma, which imposes a heavy care and financial burden on the family. Difficult-to-heal wounds can be divided into the following types according to their main causes and the nature of the ulcers: 1. Traumatic ulcers Traumatic ulcers refer to ulcers that occur mainly due to severe fractures, burns or on the basis of the tissue defects and lesions they cause. Larger tissue defects, more necrotic tissue and improper treatment are the main causes of traumatic ulcers. 2.Pressure ulcers (decubitus ulcers) are ulcers that occur when there is excessive pressure on the elevated part of the body bone for a long time. It is common in patients with hemiplegia and paraplegia who have motor and sensory paralysis and do not turn over frequently. (2) Deep coma, large burns, prolonged general anesthesia, and tightly wrapped plaster bandages. ③ Chronic wasting, malnutrition, negative nitrogen balance and other long-term bedridden patients, even if there is discomfort, they are unable to change position. 3.Radiation ulcers are caused by radioactive treatment after malignant tumor resection, and are commonly found in the skull, anterior sternum, breast area, and supraclavicular area. The ulcers are of different sizes and depths, with an uneven base, poorly grown and dirty granulation tissue, often covered with fibrin-like material, mostly accompanied by bacterial infection, with irregular and subterranean edges, surrounded by hard “leather-like” scar tissue, and thinning and hyperpigmentation of the peripheral skin. 4.Venous stasis ulcer The ulcer occurs after minor trauma or infection on the basis of venous reflux disorder, mostly seen in the lower limbs. Deep vein embolism of lower extremity and primary lower extremity venous valve atresia are the common causes of venous ulcers. Venous stasis ulcers tend to occur in the lower third of the lower leg, especially above the inner ankle. They are often characterized by hyperpigmentation, skin atrophy, thinning and brittleness, ulcers of different sizes and shapes, shallow ulcers, uneven bases, and sclerosis of the surrounding skin. 5. Arterial ischemic ulcers Ulcers that occur after minor trauma or infection on the basis of impaired arterial blood supply, mostly in the lower extremities. The common causes of arterial ischemic ulcers are: diabetic vasculopathy, thrombo-occlusive vasculitis and occlusive arteriosclerosis. 6, infectious ulcers General ulcers have secondary infections, infectious ulcers are ulcers that occur mainly due to specific infections such as fungi and Mycobacterium tuberculosis, but also include ulcers that occur mainly due to general purulent infections or on the basis of the tissue defects and lesions they cause. 7.Malignant ulcers are cancerous ulcers and ulcer carcinoma, the former such as squamous epithelial cell carcinoma and basal cell carcinoma, the latter refers to the above-mentioned ulcers, which do not heal for a long time and become cancerous secondary to the continuous stimulation of inflammation.