The back of the foot is a little swollen is also may be due to trauma causes, may also be due to autoimmune diseases, may also be due to the lower extremity vascular disease caused. 1. trauma: the dorsum of the foot, if subjected to external trauma, may cause the dorsum of the foot subcutaneous soft tissue small blood vessel rupture, appear soft tissue parts of the congestion, edema, caused by the dorsum of the foot swelling symptoms. Such as the dorsum of the foot of the extrusion injury, the dorsum of the foot of the smashing injury. 2. Autoimmune diseases: patients with autoimmune diseases may have accumulation of small joints on the dorsum of the foot, resulting in swelling caused by immune complex deposition in small joints. Common diseases such as rheumatoid arthritis, gout and so on. 3. Lower extremity vascular diseases: due to abnormal function of lower extremity venous valves or lower extremity venous insufficiency, etc., it may cause stagnation of blood in the lower extremity veins, resulting in increased hemopermeability of the lower extremity veins, and dialysis of vascular contents, which may also lead to swelling of the dorsum of the foot. Common diseases such as thromboembolic vasculitis, varicose veins of the lower limbs and so on. Swelling of the dorsum of the foot may also have other causes, need to exclude metatarsal bone fracture and metatarsal bone tumor and other diseases. It is recommended to go to the hospital in time, complete the examination to clarify the cause of the disease, and then give targeted treatment or treatment under the guidance of the doctor.