Ischemic necrosis refers to ischemic necrosis of the femoral head or other trauma-induced ischemic necrosis of the lunar and navicular bones, and ischemic necrosis of the femoral head is the most common. Ischemic necrosis is generally caused by trauma, fracture, etc., which affects the blood circulation of the bone, or by increased blood clotting, abnormal blood lipid metabolism forming plaque, and vasoconstriction of the blood supply artery to the main bone, as well as damage inside the blood vessel causing blood flow obstruction, or by labor, strain, etc., which causes an increase in pressure in the cavity of the femoral head, thus producing ischemia, which can cause collapse and hardening of the bone, thus This can cause bone collapse and sclerosis, resulting in necrosis.