Possible reasons for the darkening of the skin at the ankles include ultraviolet radiation, trauma, varicose veins, etc., which can be improved with the help of physical therapy and surgery. 1. Ultraviolet radiation: If you often expose your ankles to the sun, it will lead to long-term exposure to ultraviolet radiation, which will lead to the darkening of the skin at the ankles. This kind of patients need to pay attention to strengthen the ankle sun protection measures, usually can be gradually recovered, without special treatment. 2. Trauma: If the patient has ankle sprain, it may lead to local capillary rupture at the ankle, triggering local bruising, which will make the skin of the ankle appear black and purple, accompanied by pain, swelling and other symptoms. This kind of patients need to first local brake ankle, to avoid further aggravation of sprain, with local physical therapy, to promote tissue healing. 3. Varicose veins: The presence of varicose veins in the ankle can lead to stagnation of local blood flow, which in severe cases can lead to localized pigmentation of the skin, resulting in darkening of the skin at the ankle. This type of patient can be treated surgically to improve varicose veins and promote local blood circulation in order to improve the local coloration. It should be noted that the above treatments should be carried out under the supervision of a physician to avoid adverse reactions.