It is usually called depressed swelling, which may be caused by the following reasons: 1) local soft tissue swelling formed after trauma or fracture, usually except for local subcutaneous bruising, if the local lymphatic flow is affected, the formation of depressed swelling will not occur; 2) injury to the lymphatic vessels of the lower limbs or local lymphatic flow obstruction, which may lead to; 3) chronic functional diseases, such as heart failure, kidney failure, or systemic hypoproteinemia. This may be caused by chronic functional diseases, such as heart failure, renal failure, or systemic hypoproteinemia, in which heart failure and renal failure usually occur in both lower extremities at the same time, and systemic hypoproteinemia, in which sunken swelling occurs in both lower extremities, as well as swelling in both upper extremities and the whole body.