The bend of the foot is also clinically known as the ankle joint. Pain in the ankle joint area may be caused by trauma or autoimmune diseases. 1. Trauma: the ankle joint belongs to the composite joint of the human body, relatively speaking, the stability of the joint is poor, so there are many ligaments inside the joint to maintain the stability of the joint, when the ankle joint is subjected to external force, it may cause tearing of the ligaments around the joint, the joint capsule damage and other conditions, and the pain symptoms appear, the common diseases, such as dislocation of the ankle joint, ankle avulsion fracture, and so on. 2. Autoimmune diseases: patients with autoimmune diseases are prone to involve the ankle joint, resulting in pathological changes such as narrowing of joint space, aging of cartilage and intra-articular metamorphosis, which cause pain, swelling and functional limitation of the ankle joint, such as rheumatic ankle arthritis and gouty ankle arthritis, and so on. The symptoms of ankle pain alone cannot determine the cause accurately, and it is necessary to combine with the characteristics of the medical history and other test results to make an accurate judgment. It is recommended to clarify the cause of the disease under the guidance of a doctor and standardize the treatment.