Swollen ankle bone may be caused by chronic strain injury, cardiac insufficiency, lower extremity venous thrombosis and other factors. 1. Chronic strain: If the foot is overloaded and overworked in life, it is easy to cause chronic strain on the ankle joint, which produces an inflammatory reaction and is likely to show swelling and pain in the ankle joint. 2. Cardiac insufficiency: if the heart systolic and diastolic dysfunction, triggering the body circulation stagnation, tissue fluid recycling is reduced, it will show palpitation, fatigue and edema, etc. Edema in the lower limbs will be manifested as swelling of ankle bones. 3. Lower extremity venous thrombosis: If there is inflammation and secondary thrombosis in the lower extremity veins, due to the blockage of the lower extremity veins, clinical symptoms such as swelling and pain in the affected limbs will be shown, which may lead to ankle edema. In addition to the above reasons, trauma, rheumatic diseases, kidney function abnormalities, etc. may also cause ankle edema. If the symptoms of ankle edema are difficult to be relieved on your own, you should consult a doctor in time to clarify the cause of the disease and then carry out targeted treatment.