Common causes of ankle weakness include chronic strain, ligament injury, joint degeneration, rheumatoid arthritis, lumbar disc herniation, etc. It is necessary to consult a doctor in time to find out the cause. 1. Chronic strain injury: standing and walking for a long time, the ligaments and joint capsule of the ankle joints are subjected to repeated pulling, which easily leads to fatigue, resulting in the phenomenon of lack of strength. 2. Ligament injury: after ankle sprain caused by strenuous exercise, part of the ligament of the ankle joint may be damaged or ruptured, and the stability of the joint will be affected, which will also lead to the phenomenon of not being able to exert strength. 3. Joint degeneration: after hyperplasia and degenerative disease of ankle joint, it will lead to narrowing of joint space and wear and tear of cartilage, which will lead to soreness and weakness of ankle, and part of it will lead to swelling and rattling of ankle joint. 4. Rheumatoid arthritis: It is a rheumatic immune disease, which may lead to synovial membrane lesions in the ankle joints, causing swelling and deformity of the ankle joints, which may lead to weakness. 5. Lumbar disc herniation: when the herniated disc compresses the nerve root on one side, it will affect the sensation and muscle strength of the lower limbs, and the ankles will not be able to make strength. When the ankle can not make strength, if through rest and warmth and other self-conditioning can not be improved, you need to consult a doctor in a timely manner, ask the doctor to find out the cause of the disease, and actively cooperate with the treatment, to avoid delays in the condition.