The swelling of the back of the foot and the pain when walking may have the following causes: 1. gout, the first symptom of gout in most patients is the swelling of the back of the foot, often accompanied by an increase in skin temperature or redness and swelling of the skin, then the relevant blood uric acid tests should be performed for diagnosis and early treatment. 2. the formation of venous thrombosis in the lower extremities, if due to intermuscular vein thrombosis in the lower leg or deep vein thrombosis in the popliteal fossa, then the swelling of the back of the foot can occur. If the thrombosis is caused by intermuscular vein thrombosis or deep vein thrombosis in the popliteal fossa, the swelling of the back of the foot can occur, and it can be accompanied by obvious pain when walking, then ultrasound or radiography of the blood vessels of the lower limbs should be performed for diagnosis, and early rest, braking, and related medication should be given to prevent serious complications. If the soft tissues or bones of the dorsum of the foot develop tuberculosis or tumor, swelling of the dorsum of the foot may occur, accompanied by walking pain.