The neck of the foot is medically known as the ankle joint, and sudden pain without touching or twisting may be caused by damage to the ankle ligaments, rheumatoid arthritis, bacterial infections, synovitis, and so on. 1. Damage to ankle ligaments: If you exercise strenuously or walk too much, even if you don’t bump into it, it is easy to damage the ankle joint, the surrounding muscles, ligaments and other tissues, which leads to ankle joint pain. 2. Rheumatoid arthritis: If the patient has rheumatoid arthritis, it may lead to ankle pain. 3. Bacterial infection: When the patient has bacterial infection in the ankle joint, due to the inflammation will lead to tissue congestion and edema, the patient will easily feel the symptoms of ankle joint pain. 4. Synovitis: Inflammatory changes in the synovial membrane may occur due to infection and irritation, causing patients to experience ankle pain. Patients with ankle pain should go to the hospital in time for further treatment after a clear diagnosis.