“Pollicization” is a chronic ulcer that occurs on both sides of the lower 1/3 of the shin bone, also known as “pollicization”, “trouser sores” and “skirt sores “Polyposis”. It starts with local itching and then pain, redness and swelling, followed by rupture and water dripping, forming an ulcer that does not get better with age, getting bigger and deeper, and eventually rotting the skin in its entirety. The skin around the ulcer is affected, atrophy occurs, the color is black, causing eczema, flaking from time to time, feeling itchy. Once the ulcer occurs, the bone is exposed and the surface becomes infected, resulting in chronic osteomyelitis. Some patients have been suffering for several years or more than ten years. The characteristics of the old rotten leg is difficult to close for a long time, or although closed for a long time, every easy due to injury and recurrence, often complicated by varicose veins in the lower limbs of patients, because of long standing work or heavy load, and because of the lower limbs of the skin by injury, insect bites and eczema, etc. induced, mostly in the lower 1/3 of the calf, more medial than lateral, the disease recurrent, itchy first and then painful, followed by the formation of trauma; a few years of unhealed If the ulcer does not heal for many years and the wound is in the shape of cauliflower, it is mostly a sign of cancer. Why does the old rotten leg not heal all the time? Humans are upright walking creatures, the lower limb venous blood flow back to the upper must overcome a lot of geocentric suction. The mystery is mainly the pressure difference between the arteries and veins. The former pressure is high, the latter pressure is low, and the direction of blood flow naturally travels from high to low. In addition, there is the squeezing effect of muscle contraction when the lower limbs move, as well as the static membrane valve located inside the vein. Some people are born with weak vein walls, or the number of static valves is too little, poor structure, poor function; if usually standing still, the lower limb muscle activity is reduced, the muscle squeeze effect is not enough, the lower limb venous blood flow back is blocked, causing the pressure in the veins to rise. After a long time, the superficial veins of the lower limbs expand and thicken, and then develop to twist into a group, like a group of earthworms coiled under the skin. Patients often feel soreness and fatigue in the lower limbs, and some have edema in the back of the foot or ankle joint. If left untreated, the skin of the lower leg and ankle will become atrophied, thinner and brighter, with sparse sweat hair, darker color, eczema, and even ulcers.